Chapter 10 Domestic fuel systems
l Personal hygiene: there should be no reason for the fuel itself to be handled.
However, in the event that contact with the fuel must be made, always wear
appropriate PPE, such as overalls, gloves, hard hat, goggles and respirator
(especially in dusty environments).
Weather conditions
The prevailing weather can have a severe effect on the storage of fuels. Bad
weather, such as wind, rain, hail and snow, is often a cause for late deliveries
and even cancellations of fuel deliveries, especially in rural areas. In almost all
cases, fuel is delivered by large tanker or flat-bed vehicles that find it next to
impossible to negotiate small, narrow roads when the weather conditions are
poor. While the weather can be unpredictable in the UK, good planning of fuel
deliveries can reduce the impacts of bad weather. Ordering more when severe
weather is forecast can often mean the difference between running out of fuel
and keeping the heating on.
Similarly, bad weather can render some fuels, such as wood chip and wood KEY POINT
pellet biomass, almost unusable. Coal and coke too suffer from the negative It is vital that fuels are
effect of excessive rain, whereby the fuel can become too wet to burn kept dry and that they
effectively. Wood pellets swell from the effects of the rain and these then clog are delivered in good
fuel delivery to the fuel bed of the boiler. Wood chip biomass can begin to de- condition for optimum
compost if it gets too damp and this, paradoxically, can cause the fuel to heat combustion efficiency to
occur.
internally and spontaneously combust.
Distribution
The distribution of fuels becomes a vital consideration, especially the further
outside a major town or city you live. Natural gas coverage in the UK through
the national grid stands at around 7000 km of pipelines, but there are still many
rural areas that are too far away from the grid for a supply to be economically
viable. In these cases, other fuel supplies have to be considered.
By far the most viable fuel in rural areas is domestic heating oil, otherwise
known as C2 grade, 28 second viscosity kerosene. Distribution of this still vital
fuel is nationwide. However, kerosene poses an environmental risk if leakage
occurs, especially where the installation lies close to a watercourse, river or
stream or where the water table is high.
LPG distribution is also very comprehensive, with most areas in the UK
reachable by tanker. However, there are certain restrictions with LPG that do
not exist with heating oil, such as that the delivery driver must have line of sight
to the LPG storage tank at all times during delivery of the liquid gas. LPG is also
very expensive as a domestic heating fuel.
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Coal and coke solid fuels continue to be readily available all over the UK,
INDUSTRY TIP although many areas now forbid the use of these fuels because of the
environmental pollution they release. If solid fuel is to be used, then local
Access the Permitted
Development legislation authority advice should be sought.
at: www.legislation.gov. The use of biomass in rural and suburban areas is permitted under the Permitted
uk/uksi/2015/596/pdfs/ Development legislation, which came into force in 2008. However, some areas,
uksi_20150596_en.pdf especially suburban districts, may put restrictions on its use if they lie within
a smoke control zone. Outside of these zones, there are no major restrictions
other than a requirement not to emit ‘dark smoke’. In most cases, domestic
INDUSTRY TIP biomass does not fall into this category.
Biomass fuel sources are Proximity to dwelling
available the length and
breadth of the UK, with many The installation of fuel storage and its requirements with regard to the
companies supplying a wide proximity of the dwelling is covered elsewhere in this chapter (page 633).
variety of biomass pellets
and chips, as well as liquid SUMMARY
biofuels such as biodiesel.
A list of local biomass Fossil fuels, and more specifically coal and coal related products, have fallen
suppliers is available at: out of favour over recent years because of the damage fossil fuel combustion
www.hetas.co.uk
and the resulting CO is causing to the climate of Planet Earth. Yet, as far as the
2
‘home’ is concerned, natural gas continues to be the fuel of choice for home
heating and cooking. Similarly, natural gas still has the largest fuel usage in the
generation of electricity in the UK.
In both of these uses – electricity generation and home heating/cooking –
natural gas looks set to be the leading fuel for many years to come until a viable
renewable, cheaper and less polluting alternative becomes available.
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Chapter 10 Domestic fuel systems
Test your knowledge
1 What is the chemical formula for propane?
a CH 4
b C H 8
3
c C H
4 10
d CO 2
2 What is the approximate calorific value of natural gas?
a 38 MJ/m 3
b 38 KJ/m 3
c 21 MJ/m 3
d 21 KJ/m 3
3 Which of the following types of coal has the highest heat content?
a Lignite
b Anthracite
c Bituminous
d Sub-bituminous
4 Which Building Regulation document gives specific guidance on the
requirements for fuel-burning appliances?
a Part A
b Part L
c Part J
d Part P
5 When a bund wall is required for an oil storage tank, what volume of oil
must it be capable of holding?
a 150 litres
b 230 litres
c 100% of the volume of the tank
d 110% of the volume of the tank
6 Which regulatory body monitors, controls and guides on the use of solid
fuel and biomass fuels?
a Gas Safe
b OFTEC
c HETAS
d Defra
7 What is the minimum recommended distance between an oil storage tank
and the flue from an oil-fired appliance?
a 600 mm
b 760 mm
c 1000 mm
d 1800 mm
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8 Which of the following toxic gases that can lead to dizziness, nausea and,
in some cases, death is produced from a fossil fuel-burning appliance if
not adjusted properly?
a CO
b H O
2
c CH 4
d CO 2
9 What grade of oil is domestic kerosene?
a C
b D
c E
d F
10 What is the approximate specific gravity of natural gas?
a 0.6
b 1.0
c 1.5
d 1.9
11 What are the five categories of fuel?
12 What is added to natural gas to give it a smell that enables better
detection?
13 List at least five factors that might be considered when a client is
selecting a fuel type.
14 What is the role of Gas Safe?
15 What is combined heat and power (CHP)?
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ELECTRICAL PRINCIPLES AND PROCESSES FOR CHAPTER 11
BUILDING SERVICES ENGINEERING
INTRODUCTION
A major part of your work as a plumber will incorporate electrics. This chapter contains all the information
you need to understand the basic principles of electrical supplies and materials and the procedures for safe
electrical isolation that you may encounter. You will also learn how to test the supply safely when you have
carried out basic tasks.
By the end of this chapter you will have knowledge and understanding of the following:
● electrical supplies used in domestic plumbing systems
● the components used in electrical installations
● basic electrical tasks
● the procedures for safely isolating supplies
● identifying critical safety faults on electrical components.
1 ELECTRICAL SUPPLIES USED IN
DOMESTIC PLUMBING SYSTEMS
Documents required to design electrical
systems
A regulation is a rule or directive made and maintained by an authority. If no
regulations were in place you would be free to do as you please, but this would
create the potential for you to harm others through your actions.
Having regulations in place ensures that all the things you do are to certain
standards. The relevant UK standard for electrical works is BS 7671:2018 (the
18th Edition IET Wiring Regulations). KEY TERM
BS 7671 covers requirements for design, erection and verification of electrical European Norm number: a
installations so as to provide for safety and proper functioning for the intended number that shows that
use. Every fitting or component must have a BS number attached to it to something meets not only
a British Standard but also
show that it meets the standards. If it hasn’t, then it may not comply with the the European Standard,
regulations. You may also notice that some fittings and tools have a BS EN to ensure consistency
European Norm number. throughout the EU.
Building Regulations 2010
The Building Regulations in the UK cover the design and construction of
buildings. They also cover the health and safety of people in those buildings. The
Building Regulations state that in most cases people carrying out work should
arrange for a third party to check that work meets the required standards.
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Within the Regulations’ subsections there are letters used for different areas
that may be familiar to you: Part L, Part G and Part H. For you to work in these
areas, and for electrical provisions, you would have to obtain proof that you are
competent. This comes under Part P. Carrying out work that does not comply
with the Building Regulations is a criminal offence, and the local authorities
have the right to remove or alter those works that do not comply with the
requirements and proceed with prosecution.
Part P
This document provides guidance on some of the more common building
situations involving electrical work. For you to be able to work with any
electrical material you must first become a government-approved competent
person, able to self-certify.
The most recent document to refer to is the 2013 edition of ‘Part P: Electrical
Safety – Dwellings’. It is currently available here: www.planningportal.co.uk/
info/200135/approved_documents
At the time of writing, electrical installation work that is notifiable is when you
are:
● installing a new circuit
● replacing a consumer unit
● adding or altering existing circuits in a ‘special location’. A ‘special location’ is
defined as a room containing a swimming pool or sauna; or as a room with a
bath or shower where the work takes place within a certain distance of the
bath/shower.
All of these notifiable works require you to be a fully qualified 18 edition
th
electrician. All other works are non-notifiable.
Disclaimer: you must make sure you are familiar with the most up-to-date
version of Part P, which may have changed since the time of writing.
Different types of supplies used in
domestic plumbing systems
There are two types of electrical current:
● direct current (DC)
● alternating current (AC).
Direct current
In a DC circuit, the electrons flow from the negative (–) pole towards the
positive (+) pole. However, before the discovery of electrons, scientists assumed
that an electric current flowed from positive (+) to negative (–) and this is called
_ +
Battery conventional current. In the UK electrical science follows the conventional
current approach, which means they assume current flows from positive to
p Figure 11.1 Direct current circuit negative.
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Chapter 11 Electrical principles and processes for building services engineering
In a DC circuit the direction of conventional current never reverses. Direct
current can be produced from a number of sources, including electrochemical
batteries or photovoltaic cells.
Alternating current
KEY TERM
Alternating current, or AC, unlike direct current, does not travel in a constant
direction. It alternates – in other words, it reverses its direction of travel constantly Hertz (Hz): the SI unit of
frequency that measures
and uniformly throughout the circuit a certain number of times per second. This the number of cycles per
is called the frequency and is measured in hertz. In the UK, the frequency of second in alternating current.
alternating current for power and lighting in domestic properties is 50 Hz. 50 cycles/second = 50 Hz
V 180° 360°
+
I
_
1 cycle or period
p Figure 11.2 Alternating current cycle
The advantage that alternating current has over direct current is that AC
voltages can be easily transformed to higher or lower voltages. DC voltages are
difficult to transform. Changing AC voltages is done by the use of a transformer,
which uses the properties of AC electromagnets to change the voltages.
Another advantage is that AC can be easily transported over long distances
without excessive voltage loss and is, therefore, much more efficient than DC.
Generating AC current
KEY POINT
In the UK, large amounts of electricity are generated at high voltage in power Transformers are
stations. This is typically 25 kV and is transformed up to 275 kV or 400 kV designed to be used
systems through step-up transformers. Once the electricity is transmitted on site. They are heavy
to its region, it is transformed down to a more manageable voltage through yellow boxes, which
step-down transformers. These distribution systems then deliver electricity transform 230 V to
at the correct voltage for the load usually ending with an 11,000 V or 400 V 110 V. All cables that are
transformer to supply both three- and single-phase installations at a local level run from the transformer
are also yellow in colour.
of 400 V or 230 V.
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A network of circuits, overhead lines, underground cables and substations link
the power stations and allow large amounts of electricity to be transmitted
around the country to meet demand. Local distribution networks operate at
132 kV, 66 kV, 33 kV and 11 kV. Alongside local distribution there are high-
voltage transmission networks operating at 400 kV (the super grid) and 275 kV
(the grid). Primary substations feed supplies at either 66 kV or 33 kV – typically
to supply larger industrial installations and the secondary distribution networks
in urban and rural areas. Secondary substations connect at low voltages,
230–400 V via overhead line on wooden poles or underground cables.
Power station
25 kV 400/275 kV
Very large factory
33,000 V
Large factory
11,000 V
Civic buildings and hotels
400/230 V
Large farm
11,000 V
Transformed Hospital
Houses 11,000 V to 11,000 V
230 V 400 to 230 V
Transformed Transformed
132,000 V 33,000 V
to 33,000 V to 11,000 V
p Figure 11.3 Electricity journey map
The supply of electricity into the home is known as single phase. As mentioned
in the previous section, the electricity distributed to factories is three phase –
single-phase electricity for domestic use is taken from this.
You should also be aware that in domestic properties you actually get 230 V,
rather than 240 V (which you may see it referred to). In older industrial settings
you may see signs specifying 415 V, however since 1995 the nominal industrial
supply voltage has been 400 V. This is three-phase supply, which you will not be
qualified to work on.
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The layout of electrical supplies and
connections
Circuits
There are two types of electrical circuit:
● series
● parallel.
Domestic lighting circuits, ring final circuits and fused
connection units
The ring final circuit in domestic properties is run from the consumer unit, using
2
what is known as 2.5 mm flat profile thermoplastic cable. At the consumer
unit it is protected by a 32 A CB or 30 A fuse in the old system. It is known as a
ring final circuit because the cables from the consumer unit form a continuous
loop returning back to the unit. This means that for each ring final circuit, at
the consumer unit there will be two sets of line, neutral and circuit protective
conductors (earths). Sockets on this system will normally be used for televisions,
fridges, stereos, PCs and other household appliances.
You may also come across a radial circuit; this is a single cable from the
consumer unit and connects directly to each socket straight from the last one.
Radial circuits can also be run as separate circuits feeding just one load, such
as water heater, underfloor heating or a cooker. Figures 11.4 and 11.5 show
examples of a radial circuit and a typical ring final circuit.
p Figure 11.4 Radial circuit
p Figure 11.5 Ring final circuit
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Earthing systems
Every dwelling will have its own earthing system to protect the owner from a
fatal shock. There are several kinds of system commonly used:
● TT system
● TN–S system
KEY POINT ● TN–C–S system.
The letters in earthing These systems are designed to earth the complete property via the earthing
systems stand for: cables throughout the house. If fitted correctly then any fault should return to
● T = earth (from the earth or a point of safety.
French terre)
● N = neutral TT system
● S = separate
● C = combined. The first ‘T’ stands for terre, and the second ‘T’ means that all exposed
metalwork is connected directly to earth via a large copper rod stuck directly
into the ground outside. This system is commonly used in rural areas, and can
be very hard to find as foliage hides the rod. If you do find it, do not touch or
disconnect the connections for any reason.
Electricity supply LABEL − Safety
(usually overhead) Electrical company isolator electrical
Metal water pipe connection
DO NOT REMOVE
Metal gas
pipe
100 A
16 mm 2
Main earthing terminal
10 mm 2
10 mm 2 Gas meter
LABEL − Safety electrical
connection DO NOT REMOVE
Earth rod
Water Gas
service service
pipe pipe
p Figure 11.6 TT system
TN–S system
This is a very common system, which connects the earth conductor back to the
metallic sheath of the distributor’s service cable as it enters the property. This
sheathing provides a separate neutral and earth route back to the sub-station
supply transformer.
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Electrical company isolator LABEL − Safety
electrical
connection
DO NOT REMOVE
Metal gas
pipe
100 A 16 mm 2
Main earthing terminal
10 mm 2
10 mm 2 Gas meter
LABEL − Safety electrical
connection DO NOT REMOVE
Metal water pipe
Water Gas
service service
pipe pipe
p Figure 11.7 TN–S system
TN–C–S system
This system is also known as a protective multiple earthing system, or PME.
It relies on the neutral being earthed close to the source of supply and at points
throughout the distribution system. There is also a neutral-to-earth connection
at the intake of the installation. The ‘C’ means the supplier uses a combined
earth and neutral. The ‘S’ means the earth and neutral are separate within the
customer’s property.
Electrical company isolator Service protective LABEL − Safety
conductors electrical
connection
DO NOT REMOVE
Metal gas
pipe
Main
switch
100 A
16 mm 2
Main earthing terminal
10 mm 2
10 mm 2 Gas meter
LABEL − Safety electrical
connection DO NOT REMOVE
Metal water pipe
Water Gas
service service
pipe pipe
p Figure 11.8 TN–C–S system
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Temporary bonding
While working in a dwelling you will no doubt have to cut into existing pipework
to add a new appliance, or take it away depending on the job specification.
This will mean that you will break the continuity bond between any exposed
metal or bonded material and ‘earth’. It is essential that the earth continuity
is maintained, and you can do this by using what is known as a temporary
bond – a 10 mm wire sheathed as earth that is attached to crocodile clips
2
which you can attach at each end. Once the work has been completed you
may remove the clamps and test for continuity again throughout the system.
If paint is present, you must ensure that it is removed fully to enable a sound
connection. There are some exceptions to bonding metallic pipes that have
insulated sections at their point of entry. You MUST consult regulation 411.3.1.2
of BS 7671 before cutting into or bonding any pipes.
Protection methods used on electrical
systems
Circuit breaker
The protective device in a consumer unit is also known as a circuit breaker
(CB). This is an automatically operated switch designed to protect an electrical
circuit from damage caused by overload or short circuit. You can also turn it
off manually to isolate individual circuits. When doing so it is advised that you
lock off the circuit breaker and perform the full safe isolation procedure before
any work commences. While work is being carried out, the circuit breaker must
remain securely isolated with warning signs posted.
Residual current device
A residual current device (RCD) is more sensitive than an CB, and when installed
in a consumer unit its job is to protect the ‘group’ of circuits. It is larger than an
CB and will have a test/reset button on its front. An RCD can be a lifesaver – it
works by constantly monitoring the electric current flowing along the circuit.
It is so sensitive that it can detect electricity flowing down an unintended path
– such as a person. If this happens the RCD will turn off the circuit within a
fraction of a second and prevent the person receiving an electric shock.
Rewirable fuses
Rewirable fuses were designed so that the wire (fuse) would burn and melt if
too high a current passed through it, disconnecting the flow. The only thing it
would detect would be a surge in the current above the specified level of the
fuse used. Fuse sizes were generally 5 amp, 15 amp and 30 amp. The fact that
the consumer could replace the wire if it had ‘blown’ led to many problems with
electrical fires. Many consumers did not realise the risks in trying to avoid the
inconvenience of the fuse tripping (by melting), and would put in a significantly
p Figure 11.9 Rewirable fuses larger wire or even a nail to keep this from happening.
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RCBO circuit breaker
To comply with the 18th Edition Electrical Regulations, residual current breakers
with overload protection (RCBOs) can be installed. RCBOs combine the
functions of an CB and an RCD in one unit. They are used to protect particular
circuits, instead of having a single RCD for a whole building.
Cartridge fuses
Most commonly found in appliance plugs, these small fuses act as protection
against surges in current. Like a rewireable fuse, a cartridge fuse has a wire
inside that will melt. But instead of the consumer being able to change the wire
inside, they would need to replace the whole cartridge.
The relationship between fuse size and
current
p Figure 11.10 RCBO
The code of practice for portable appliances has standardised the following:
● For appliances up to 700 W, a 3 A red-coloured fuse is used.
● For appliances between 700 W and 3,000 W, a 13 A brown-coloured fuse is
used.
● 5 A black-coloured fuses are only used for equipment rated up to 700 W
with higher inrush currents (i.e. a higher initial current when switched on).
Non-rewireable plugs will have the appropriate fuse rating marked on them.
When changing a fuse check that the replacement fuse is of the correct rating in
amps, is manufactured to BS 1362 and is approved – an ASTA mark shows that p Figure 11.11 Cartridge fuse
is has been approved for safety.
2 COMPONENTS USED IN
ELECTRICAL INSTALLATIONS AND
BASIC ELECTRICAL TASKS
Incoming electrical systems in domestic
dwellings
The electricity supply cable from the Distribution Network Operator (DNO)
arrives in the house and is terminated into an enclosure known as the electrical
service head (cut-out). The DNO’s service fuse is fitted into a sealed unit
known as the fuse carrier. When the fuse carrier is placed into the cut-out it is
sealed. The reason the fuse is sealed is to prevent tampering. The removal of
a service fuse can only be carried out by a person approved by the DNO. The
seal is a small wire which locks the fuse carrier to the service cut-out. Supply
cables (known as Tails) are then taken from the cut-out to the service meter.
These cables are sealed at connection points to the meter. These supply cables
(Tails) have an outer grey PVC covering which provides a form of mechanical
protection and an inner layer of PVC insulation which is used to cover the
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supply conductors. The colours for these conductors were red and black for
installations constructed up to 2004 and since then the colours blue and brown
have been introduced.
Meter
Main fuse
Consumer unit
Main double pole
switch on consumer unit
To water service
To gas service
Line and
neutral
cables Main earth terminal (MET)
Supply cable
p Figure 11.12 Fuse box
KEY TERMS The meter receives the electricity supply from the service head and measures the
consumption of power in your house. There may also be added components such
Meter: a display that as time clocks and switches if you make use of the ‘cheap rate’ night-time supply
enables the local company
to take readings for your bill. known as Economy 7. The dials on the meter record the number of units of power
Units of power: these are used so the customer can be billed. This then feeds the consumer unit via a pair of
read as kWh (kilowatts per large wires – one blue (old cable colour = black) and one brown (old cable colour
hour). = red). The wires from the meter terminate at a double pole switch (double pole
switches break both the line and neutral) inside the consumer unit. On the other
side of the switch, the neutral is connected to a neutral bar, which accommodates
all the blue (old cable colour = black) neutral conductors from your circuits.
The line, brown (old cable colour = red) cable goes to a bar, which sits behind
one end of all the fuses. The link from here to the terminal of each circuit is
protected by a fuse mounted between the two.
Another connector block called the main earthing terminal accommodates all
the earth (green and yellow) wires from your circuits and connects them back
to the main supply earth terminal.
On the consumer unit you will find switches you can touch to turn off and on as
p Figure 11.13 A meter point with
old wiring colours required. The main double pole switch is usually coloured red and will isolate all
the power to all of the circuits.
Next to this main switch you will have individual circuit breakers or other types
KEY TERM of circuit breakers that you can use to isolate a single circuit, again via a switch.
Permitted: being allowed to Remember that you are not permitted to remove the casing of the consumer
do something. unit or tamper with the cables – you must be a qualified electrician to do so.
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Unfortunately, you will not always be working on a new type of consumer
unit. Figure 11.14 shows an old consumer unit which is still very common in
older buildings/dwellings. Sometimes it can be unclear how to isolate specific
circuits so you should stop work and seek expert advice. If in doubt a qualified
electrician must always be called to carry out the work.
Types of wiring used in electrical systems
All cables that run throughout a dwelling will have copper inside – copper is one p Figure 11.14 Old fused
of the best metals available for keeping resistance to a minimum. It’s very cheap consumer unit
in comparison with silver, which also has a very low resistance.
Thermoplastic (PVC) cables (twin and cpc)
‘Twin and cpc cable’ is normally the grey-coloured cable you will see when you
remove floorboards to install pipe runs. It comprises two insulated current-
carrying conductors and an uninsulated protective conductor (earth). Line and KEY TERM
neutral are individually insulated, with different colours for identification – the
protective conductor is bare but is still mechanically protected by the main grey Sheath: insulation around
PVC sheath. The protective conductor (cpc) does not have a PVC covering in the main copper cable,
order to keep the manufacturing cost down. Anyone working on the circuit must made from PVC plastic.
ensure that the bare protective conductor is sleeved to enable identification.
Twin and cpc cable comes in many thicknesses and in single lengths up to 150 m
long. The most common sizes in domestic installations are 1.5 mm for lighting
2
and 2.5 mm for power circuits, but you can get a large cable for electrical
2
shower units in domestic dwellings up to 10 mm in size. This needs to be large
2
to accommodate the draw of electricity (up to 10.5 kW) from the consumer p Figure 11.15 Old twin and cpc
unit to the shower unit. A smaller cable would be liable to melt due to the heat cable
produced and risk starting a fire.
Flex and heat-resistant flex cables
Flexible (sometimes shortened to ‘flex’) cables and heat-resistant flexible cables
are designed – as the name suggests – to be flexible. (As opposed to flat profile p Figure 11.16 New colour code
cable, which is sturdier, and is designed to remain where the electrician places for twin and cpc
it.) Flex cable looks like the kind of cable you would find on an appliance. Flex
cables are primarily used to connect appliances to fused connection units – for
example boilers, control valves and macerators.
Heat-resistant flex can be used as standard flex, but it is particularly suitable
in high-temperature zones – for example in an airing cupboard to connect the
immersion heater. These cables look very similar, so you will need to read the
information on the cable itself, which will show the temperature it can withstand.
p Figure 11.17 Heat-resistant
cable
Types of cable protection
When installing cables, you must ensure that all your hard work is not wasted KEY TERM
by following the relevant regulations. For example, sometimes a cable cannot Chased: in the case of
be chased in a wall or under the floor, and in this case you would have to use pipework or cables, this
either conduit or trunking to protect it. Cables must always be protected when means they are fitted inside
buried inside walls. a cut made in a wall.
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Electrical conduit is a metal or plastic pipe through which electrical wires are
run to a point of termination. The conduit protects the wires and is usually
used in exposed locations, such as along the outside surface of a wall. You will
see this most commonly where outside lighting has been added to a building’s
surface, or in offices.
Electrical conduit is fairly complex to fit – not dissimilar from some plumbing
materials.
p Figure 11.18 Trunking
Trunking is another way of protecting cables, and this is most commonly found
inside domestic dwellings. Like conduit its design allows the electrician to run
the cable inside. It protects the cable and guards against accidental damage.
Size of conductor and current carried
For equipment to operate correctly it requires a specific amount of operating
current (supply/load current). Manufacturers of equipment provide technical
information to enable the correct amount of supply/load current to be
determined. Once the supply/load current has been determined, a conductor
capable of carrying this current can be selected.
The size of conductor is directly related to the amount of current it is required
to carry. The higher the current demand the larger the conductor required.
Conductor size is measured as cross-sectional area or CSA. The CSA in mm
2
can be determined using the formula CSA = πd /4 where π = 3.142 and d = the
2
diameter of a conductor in mm. Cable selection can be a complex task and one
that should only be carried out by a competent person.
Table 11.1 shows some examples of simple rule of thumb methods for flexible
cable selection (flexes). Remember flexes are those cables typically used to
connect equipment to accessories such as FCUs.
Table 11.1
Approx. number of wires
CSA (mm ) Maximum current (A) in the flex
2
0.75 6 24
1 10 32
1.25 13 40
Note: This table will only apply to flexible cables of no more than 5 meters in length.
So, using the information in Table 11.1, if you were required to check if the
correct flex was connected to a boiler in relation to current demand of the
boiler, you could follow the procedure below:
1 Safely isolate the boiler.
2 Remove the flexible cable from the FCU.
3 Count the number of strands.
4 Use the table to allow you to determine the CSA of the flexible conductor.
5 Using the same table you can then determine the current carrying capacity
of the flexible cable.
6 You can then compare this value to the to the boiler current demand.
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Table 11.2 shows a simple rule of thumb method for replacement of appliance
flexes. For flexes protected by the fuse in a BS 1363 plug there is no limit
to their length providing their cross-sectional areas (CSAs) are as stated in
Table 11.2.
Table 11.2
Min. flex CSA (mm ) Fuse rating (A)
2
0.5 3
1.25 13
Other considerations such as voltage drop may limit flex lengths.
Components of electrical systems and
basic electrical tasks
Spurs and fused spurs
A spur is most commonly connected into a ring final circuit to add an additional
socket. A non-fused spur is commonly connected to a ring final circuit to add
one additional socket. An accessory known as a ‘fused connection unit’ (FCU)
can be included as part of an RFC or radial circuit to supply Items of equipment
such as combination boilers or underfloor heating, and is also commonly used
to supply S-plan or Y-plan hot water heating controls systems. From the FCU a
flexible cable will be used for direct connection to the item of equipment.
Spur from junction box
p Figure 11.19 Spurs and fused spurs
An unswitched fused connection unit is one that does not have a manual on/off
double pole switch, it only contains a fuse compartment and fuse. This type of
accessory is used to supply items of equipment where it is important to ensure
they cannot be easily switched off, e.g. security alarm panels.
You will probably also encounter double-pole (DP) switches. These break the
live conductors and when operated will provide complete isolation of the
connection unit. This item of equipment should always be placed in a lockable
position. The switch that forms part of an FCU will also be double-pole, and
a fuse compartment is also incorporated. This fuse compartment is designed
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so that the fuse can be removed for safe isolation purposes and ease of
maintenance.
Junction boxes
KEY POINT Below is an example of an installation where a non-fused spur has been taken
FCUs of his type are from a junction box to supply an accessory known as a ‘double-pole fused
sometimes incorrectly connection unit’. (For clarity the fuse carrier section of the FCU has not been
referred to as switched shown). It can be seen that the section of cable from the junction box to the
fused spurs. This is a FCU is what is referred to as the ‘non-fused spur’. This term is given to this
site term and should not section of cable because the cable is a separate branch from the main circuit
be used.
and is not protected by a protective device at the point of connection to the
main circuit. The cable supplying the appliance from the FCU will be normally be
of the flexible type as described earlier.
Flex to appliance Ring final circuit
(cpc left out for clarity)
Fused spur
Safely isolated circuit connection unit
Junction box
2.5 mm² flat profile cable
Ring final circuit
p Figure 11.20 Typical junction box wiring diagram with connections to terminals
SPUR
NEW COLOUR CODE
RING IN RING OUT
Junction box
p Figure 11.21 Typical junction wiring box
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Chapter 11 Electrical principles and processes for building services engineering
It is only permissible to connect one unfused spur per socket on a ring final
circuit. The total number of fused spurs allowed on a ring final circuit is
unlimited.
Spur from junction box
p Figure 11.22 Limitations on fitting spurs
Plugs
A plug is a simple device that allows you to safely connect or disconnect an
appliance to and from an AC socket. A common cause of electrical faults is poorly
wired plugs. Here is a step-by-step guide to wiring a plug correctly and safely.
Earth wire
Fuse
Neutral wire
Line wire
Outer insulation Cable grip
p Figure 11.23 A correctly wired plug
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Wiring a three-pin plug
1 First you will need to strip off about 4–5 cm of the outer cable sleeve. Slit
the outer sleeve of the cable lengthways using an electrical knife or flexible
cable stripping tool, being careful not to cut into the coloured wires or
yourself. Peel the outer sleeve away and cut it off using cable cutters or wire
cutters.
2 Separate the wires and cut them to the correct length using wire cutters.
Measure the length they need to be against the plug, matching them up to
the correct terminal points.
3 To remove the insulation you will need wire strippers or wire cutters. Be
careful not to cut into the individual strands of wire and only cut off about
5 mm of the insulation. Once you have done this you then need to twist the
ends of the wire so you have a hard cable to work with, rather than individual
strands.
4 Now you need to connect each wire to the correct terminal. To start you
need to slacken the screw on top of the terminal and push the bare wire
into the hole created. The correct tool to use for this type of terminal is an
electrician’s screwdriver. All electricians’ tools are designed and fitted with
p Figure 11.24 Wiring a three-pin insulation to protect the user from an electric shock. You then need to re-
plug tighten the screw down on to the bare cable and terminal body. Make sure
the terminals are tight and that there are no bare wires or loose strands
of wire showing or overhanging the terminal, as a loose wire could cause a
short circuit.
The terminals are normally stamped with the following letters:
● L = line (brown)
● N = neutral (blue)
● E = earth (yellow and green).
You may also notice the earth symbol, shown in Figure 11.25.
If not, the top terminal is usually earth, the terminal attached to the fuse is
line and the last terminal is the neutral.
Older appliances may have plugs with wires of different colours:
● red – line
p Figure 11.25 Earth symbol
● black – neutral
● green – earth.
KEY TERM 5 Once you have completed Step 4, you will need to tighten the cord clamp
Terminal: the entry of the over the cable. Make sure the cord clamp is gripping only the outer sleeve of
cable to a fixed position the cable, and not the coloured wires.
where it is known to 6 Before screwing on the top of the plug you need to check that you have
terminate/fix. used the correct size of fuse for the appliance. There are three standard fuse
ratings: 3 A, 5 A and 13 A.
7 The final checks to make before screwing the plug top back on are that
the wires are fitted correctly in the channels provided and that they will
not become crushed. Most importantly is to recheck the wiring you have
completed and there are no conductors or copper showing.
All the tools you use for cutting and removing sheathing from the cable must
be specifically made for the purpose. These are known as insulating cutters
(or cable cutters) and insulating strippers. You should not use a Stanley knife
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to carry out this procedure. As with the electrician’s screwdriver, these tools
have been manufactured to prevent the user getting an electric shock if the
system accidentally goes live during the work.
3 ELECTRICAL TESTS AND
PROCEDURES FOR SAFELY
ISOLATING SUPPLIES p Figure 11.26 All-in-one stripper,
crimper and cutter
Being able to safely isolate a supply will not only allow you to do your work but
could also save your life and that of others. Your day-to-day duties may involve
fault diagnostics and rectification, but you shouldn’t leave it at controlling the
immediate risk to yourself – it should be your focus to ensure that others’ safety
is not compromised while you are working or after you leave. Any work that
involves electricity should include the formal process of ‘safe isolation’. This set
procedure (discussed later) lays down a set of rules to be followed to ensure
the part of electrical circuit you need to work on cannot become live under any
circumstances. p Figure 11.27 Electrician’s knife
Testing
You must understand the following electrical tests:
● continuity of conductors: protective conductors, including protective bonding
conductors, and in the case of ring final circuits, live conductors
● insulation resistance
● polarity.
It is essential to use the correct equipment when carrying out these tests.
Testing should be carried out in such a manner that no danger arises to person,
livestock or property.
Multifunction meters
There are many different meters available commercially for testing electrical
circuits, so great care has to be taken to ensure an approved and appropriate
meter is used. Individual meters can be used for continuity, polarity and
insulation resistance but good multifunction meters also do the job by changing
between the required test functions on the dial.
p Figure 11.28 Multimeter/
Before you test, the test meter and probes must be GS38-compliant to protect ohmmeter – the left dial is set
the user from electric shock. Before doing any tests the meter and leads must to the Ω scale and the right
be checked to make sure they are sound with no cracks or damage. The test dial is set at 20 Ω
probes must be protected and ideally no more than 2 mm of metal showing.
The correct meter and settings need to be chosen and understood. Remember, if
you are unfamiliar with the meter, consult the manufacturer’s instructions and
seek advice from a qualified person. The prime concern with testing is safety
and this means ensuring the circuit is completely isolated and secure.
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Incorrect method of connecting leads Continuity of protective conductors
–ve The purpose of testing earth continuity is to verify that the protective
+ve bonding in the house is not broken. Note that safe isolation is essential
and must be carried out before the test. To measure the continuity of
Current flow has to travel across the hinges protective conductors, a low-resistance ohmmeter is required, typically in
the range of 0.2–2 ohms. Note that general-purpose multimeters are not
Correct method of connecting leads
suitable or capable of carrying out this test.
–ve +ve
Method
1 Select the correct meter (low-resistance ohmmeter).
Current flow is straight from clip to clip 2 Select the correct scale (depends on meter/manufacturer).
p Figure 11.29 Incorrect vs correct 3 Check the meter/leads for damage.
method of connecting leads 4 Insert the leads in the correct location (follow the manufacturer’s
instructions).
5 Correctly connect the leads – as shown in the diagram.
6 ‘Zero’ or ‘null’ the meter leads so meter says 0.00 Ω.
7 Test between all earthed points. Test results between conductive parts
should be in the order of 0.05 Ω or less. Further details on specific results is
given in BS 7671 or consult a qualified electrician.
In a room containing a bath or shower, tests are carried out with a low-
resistance ohmmeter to prove bonding between, for example, hot and cold
water, central heating, a heated towel rail, lighting circuit and shower.
Supplementary
bonding
conductor
Low-resistance ohmmeter
p Figure 11.30 Testing for continuity
Polarity
The purpose of testing for polarity is to ensure that line is line and neutral is
neutral. All single pole switches must be in the line conductor. All light fittings
and sockets must be connected the correct way round. Failure to check this can
lead to electric shock.
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Polarity can be checked by different methods, including visual inspection and
continuity testing. The main point is to ensure that the line and neutral are not
crossed over in a circuit.
Polarity and continuity testing
This test uses the same low-resistance ohmmeter as the previous tests and it
is again essential to ensure safe isolation has been followed carefully to avoid
the risk of electric shock. Once the meter has been selected, checked and low
ohm range chosen, the leads are zeroed. The main switch on the consumer unit
is off, lamps removed, all fuses removed, circuit breakers and RCBOs are off. A
temporary link is put into the safely isolated board as shown in the diagram.
The low-resistance ohmmeter is then connected between the line and cpc in the
switch. To check polarity, the meter is connected next between the line and cpc
in the ceiling rose at the end of the circuit. By turning the switch on and off the
meter will show a low reading followed by a high reading, proving polarity as
the circuit is broken.
Ceiling rose
at end of circuit
Temporary link
Switch
Main switch off
All fuses removed
Circuit breakers off
Test instrument 0.20Ω
Lamps removed
Note: the test may be carried out either at lighting points or switches
p Figure 11.31 Polarity and continuity testing
Insulation resistance
The purpose of the insulation test is to verify that the insulation of conductors
provides adequate insulation, is not damaged and that the live conductors or
protective conductors are not short-circuited or leaking over-current that could
give rise to fire or electric shock.
The meter used is a specific insulation resistance meter (or multifunction meter
that is approved). The meter setting is in megaohms (MΩ). p Figure 11.32 Insulation
resistance meter
The meter must be capable of supplying an output test voltage of 250 V
DC, 500 V DC or 1,000 V DC For standard domestic installations, the meter
will need to go up to 500 V DC and readings that can be expected between
conductors can range from 0.00 MΩ to over 2,000 MΩ.
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As with previous tests, precautions such as safe isolation must be followed.
Also, all sensitive equipment and lamps will need to be removed as the test can
potentially cause damage.
Method
At one end of the disconnected, safely isolated circuit, the meter is connected
between the line and earth by crocodile clips. It is important not to touch the
conductors during the test as the meter generates large voltages that can harm.
The meter is set to 500 V DC and when the circuit is clear of lamps/sensitive
equipment the voltage can be applied by pressing the test button.
N P
C.P.C.
Edison screw
KEY POINT Single pole switch lamp holder
Short circuits may occur Safety
between live conductors. isolated
A neutral counts as a circuit
live conductor. Such
short circuits are likely
to result in a very high Set on 500 V d.c.
current and will therefore
quickly trigger an over-
current protection p Figure 11.33 Testing insulation resistance
device. Consider the
effect this would have on If the insulation around circuit cables are in good order no conductivity will
an old fuse box in which exist between the conductors and therefore a good insulation resistance value
a nail has been put in will be achieved, typically much greater than 200 MΩ. If the cable insulation
place instead of the
correct size of fuse – you has deteriorated, then conductivity between conductors may exist. This will be
can see that the risk of apparent when readings below 1 MΩ are recorded. If values below 1 MΩ are
melting cables and the recorded and there is no obvious reason then always call an electrician, do not
potential for a fire are reinstate the circuit. Note remember never apply a voltage of 500 V DC across
highly increased. the live conductors of a circuit unless the equipment has been removed.
If the test between line and earth is successful, continue and test between all
the other combinations of conductors following the same procedure. If a low
reading is found, this could be a short circuit.
Short circuit
Switch closed
Phase
Majority (large) Electrical
current flow load
Neutral
p Figure 11.34 Short circuit
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You will be involved with isolating the circuit to complete works for two
main reasons. You may be asked to remove an appliance from a plug,
which is the easiest method of isolation. You might be asked to isolate an
immersion heater from a fused connection unit in order to repair, replace or
decommission an electrical shower. Failure to isolate supplies correctly can
result in electric shock.
The following procedures will enable you to complete these works correctly and
stay safe. The sequence below will enable safe isolation from the consumer unit
(if the wires need disconnecting for a complete decommission, remember that
you are not allowed to work inside the consumer unit).
Safe isolation procedure
Step 1 Step 2 Step 3 Step 4
Check with the occupier/user Identify the type of supply system: Locate and identify the circuit/equipment to be isolated. Select an approved voltage-
that it is acceptable to isolate • TN–S: Double-pole main switch indicating device; this must
the circuit/equipment. • TN–C–S: Double-pole main switch be verified:
• TT: DP isolation – all circuits and • on a known supply or
equipment. • on a proving unit.
no
Step 8 Step 7 Step 6 Step 5
Fit appropriate lock-off device Isolate circuit/equipment by Identify suitable Verify the circuit/equipment is
and locks. Person carrying out switching off: means of isolation. functional. Use the approved
works to retain key. • double-pole/three-phase isolator satisfactory voltage-indicating device to
• circuit-breakers (or by with- verify circuit/
drawing the fuse). equipment. If the
circuit is non-
operational, dead
testing may be
required to verify
the circuit.
no
Step 9 Step 10 Step 11 Step 12
Fit warning label for isolation Verify the circuit/equipment is Re-check the approved voltage- Circuit/equipment should be safe
and identified work. isolated. Use the approved voltage- indicating device is still functional: no to carry out the work. Always
indicating device to verify circuit is • on the same known supply as remain vigilant and recheck with
dead. Test between all conductors: Step 4 voltage-indicating device when
• Line–Line • on the same proving unit as moving away and returning to
• Line–Neutral Step 4. the circuit/equipment.
• Line–Earth satisfactory satisfactory
• Neutral–Earth.
yes yes
p Figure 11.35 Safe isolation procedure
Once you have done all the above, you should have confirmed that circuit is
dead. It is important to remember to explain to the customer what you are
about to do to ensure that they are happy, but also so that if they notice any
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defects later they will then know to come to you instead of going directly to
the consumer unit and trying to operate something they shouldn’t. This is why
it is important to ‘lock off’ and label the circuit breaker/s you have isolated.
Remember, if you are in any doubt at all, consult a qualified electrician.
Safe isolation of valves, etc from a fused
connection unit
Some works you carry out will involve a simple change of valve, such as a pump,
zone valve or immersion heater. These are usually connected via a flex to the
fused connection unit. Some fused connection units will have a red neon light
indicating when the supply is on; if the switch is flicked off the light will go out,
but this cannot be entirely trusted as the load may have been disconnected, or
the neon could be broken.
It is always safest to carry out a full isolation of the system following the
p Figure 11.36 Switched fused procedures described, but if this cannot be done the following procedure should
connection unit with neon be adhered to.
1 Locate the source of supply (this will be direct, at the valve’s electrical
connection box).
2 Isolate the source of supply by turning off the switch on the fused
connection unit and removing the fuse. (It is your responsibility to have
control of the fuse and not leave it where somebody can put it back in the
unit – a way to avoid this is by locking the fuse housing, as shown.)
3 Test your voltage indicator on a known good source.
4 Test that the supply is isolated at the valve/appliance electrical point. (Line
to neutral, earth to line, earth to neutral.)
5 Re-test using the voltage indicator using a known good source to ensure your
meter/voltage indicator is still functioning.
6 Once confirmed, you may remove the connections at the valve/ appliance
terminal and change it as required.
Other voltage indicators, such as voltage sticks, are available. These must not
be used to confirm full isolation of any component/circuit – only an approved
voltage indicator may be used.
4 IDENTIFY CRITICAL SAFETY
FAULTS ON ELECTRICAL
p Figure 11.37 Locked fuse
COMPONENTS
All faults – incorrectly fitted cables and components – must be reported to
your boss or the customer. If you have not created the fault but you find a fault
with the existing circuits, an 18th edition electrician must be brought in to
remedy it.
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What to do if a colleague suffers an
electric shock
If you see someone who appears ‘frozen’ on a circuit or is lying unconscious,
the very first thing you must do is shut off the power supply. If you touch that
person without doing this, you are basically continuing the circuit and making
yourself ‘live’. If you cannot find the source of power, use something non-
conductive to dislodge the victim from the circuit, such as a wooden board
or heavy-duty plastic. Once you have removed the victim from the source of
electrical power you must then check for vital signs and carry out first aid. Even
if apparently unharmed, because the victim has been in direct contact with
electricity it is advisable for them to seek medical advice at a hospital, as the
rhythm of the heart may have been affected.
SUMMARY
As a plumber you will often come across electrics in your career. During this
chapter we have covered the electrical knowledge that a plumber would
be expected to know in order to safely carry out basic electrical tasks. This
includes understanding electrical supplies used in domestic plumbing systems,
the components used in electrical installations, procedures for safely isolating
electrical supplies, identifying critical faults, and undertaking basic electrical
tasks.
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Glossary
Acceleration: a measure of the to employers and employees on all water will drop but the velocity of
rate at which an amount of aspects of workplace relations and the water increases. When the pipe
matter increases its velocity. It is employment law. increases back to its original size,
measured in a change of velocity Advisory: recommended but not then the velocity will decrease and
over a period of time and, as such, enforced. the pressure will increase almost to
is directly proportional to force. It its original pressure.
will increase and decrease linearly Aesthetically pleasing: beautiful Boiler cycling: the process of the
with an increase or decrease in in appearance, good-looking, constant firing up and shutting down
force if the mass remains constant. in keeping with the rest of the as the system water cools slightly
It is measured in metres per second surroundings. wastes a lot of fuel energy. Applied to
squared (m/s ). Air infiltration: a process where air when a heating system has reached
2
Acceleration due to gravity: the can get into a system and cause air temperature, the boiler shuts down
rate of change of velocity of an locks and corrosion. on the boiler thermostat. A few
object due to the gravitational pull Amp (and milliamp): unit minutes later the boiler will fire up
of the Earth. If gravity is the only of electrical current, the again to top up the temperature as
force acting on an object, then the measurement of ampere. the system loses heat and, after a few
object will accelerate at a rate of seconds, shuts down again.
9.81 m/s downwards towards the Annealing: a process that involves Boiler interlock: ‘locking out’ on
2
ground. heating the copper to a cherry-red
colour and then quenching it in the overheat high-limit thermostat.
Accent: the way in which people water. This softens the copper tube BSP: British Standard Pipe.
pronounce their words. so that the copper can be worked
Accident: an unexpected or without fracturing, rippling or BSPT: British Standard Pipe Thread;
the type of thread used on screwed
unplanned event that could result deforming. low carbon steel pipes and fittings.
in personal injury, damage and, Anodising: coating one metal with
occasionally, death. When an another by electrolysis to form a Calorific value: the amount
accident occurs, there are always protective barrier against corrosion. of energy stored in the gas in
reasons for it and if there’s a reason, its uncombusted state. It is
then there is usually blame. Asbestos: a fibrous silicate material the amount of energy released
highly resistant to heat. when the gas is combusted. It is
Actual capacity: (of a cistern) the measured in megajoules (MJ) per
maximum volume it could hold Atom: a fundamental piece of cubic metre or MJ/m .
3
when filled to its overflowing level. matter made up of three kinds of
particles called subatomic particles Centre to centre: measuring from
Acute injury: occurs when manual – protons, neutrons and electrons. the centre line of one pipe to the
handling or lifting causes centre line of another, so that all
immediate pain and injury. Benchmarking: this is now a
compulsory requirement to ensure the tube centres are uniform. This
Adhesion: the way in which that systems and appliances are ensures that the pipework will look
water molecules ‘stick’ to other installed in accordance with the perfectly parallel because all of
molecules they come into contact regulations and the manufacturer’s the tubes will be at equal distance
with. instructions. It also safeguards from one another.
Advisory, Conciliation and any guarantee against bad Chamfer: to take off a sharp edge
Arbitration Service (ACAS): an workmanship. at an angle. If we chamfer a pipe
organisation that provides free and Bernoulli’s principle: when a pipe end, we are taking the sharp,
impartial information and advice reduces in size, the pressure of the square edge off the pipe.
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Glossary
Chased: in the case of pipework or droplets that are collected in Dialect: a combination of the
cables, this means they are fitted the boiler and discharged via the way people pronounce words,
inside a cut made in a wall. condense pipework. the vocabulary they use and
the grammatical structures they use.
Chronic injury: type of injury that Corrosion: any process involving
can take weeks, months or even the deterioration or degradation Dressing: the term used by
years to develop. of metal components, where the plumbers to describe the preparation
metal’s molecular structure breaks of the appliances ready for
Code of practice: similar to a
British Standard, this is a set of down irreparably. installation.
rules that explains how people Crimping: the process of pressing Duty holder: a person who controls,
should behave in their chosen the fittings into a copper pipe using reduces or eliminates health and
profession. a ‘press fit’ or crimping tool. safety risks that may arise during
Cohesion: the way in which the CSCS card: this stands for the construction of a building or
water molecules ‘stick’ to one Construction Skills Certification during future maintenance. They
another to form a mass rather than Scheme card. Its purpose is to must also provide information for
staying individual. This is because confirm that people who work the health and safety file.
water molecules are attracted to in the built environment have Duty of care: in British law, the
other water molecules. the necessary competence, and moral and legal obligation imposed
identifies their qualifications. For on an organisation or individual,
Combination (‘combi’) boiler: a example, a trainee plumber would which necessitates that a standard
boiler that provides central heating carry a small plastic ID craft or of reasonable care is adhered to.
and instantaneous hot water.
operative card that identifies them If the standard of care is not met,
Competent: having the necessary as a person enrolled on an NVQ then the acts are considered to
ability, knowledge or skill. programme but not yet qualified. be negligent and damages may be
Comply: act in accordance with; Delegation: sharing or transfer of claimed for in a court of law.
meet the standards of. authority and responsibility, from Electrolyte: a fluid that allows the
Compression: the process of water an employer or supervisor to an passage of electrical current, such
hitting a bend at forces that cause employee. as water. The more impurities (such
a shock wave of air upwards. Derived units: combinations of as salts and minerals) there are in
the seven base units by a system the fluid, the more effective it is as
Conciliation: an alternative dispute an electrolyte.
resolution process whereby the of multiplication and division
parties to a dispute agree to calculations. There are 21 derived Equipotential bonding: a system
use the services of a conciliator, units of measurement, some of where all metal fixtures in a
who then meets with the which have special names and domestic property, such as hot
parties separately in an attempt symbols. and cold water pipes, central
to resolve their differences. Deviate: change; do differently heating pipes, gas pipes, radiators,
Collective conciliation is when a from the original plan. stainless-steel sinks, pressed-steel
group of employees is involved, Dew point: the temperature at enamelled washbasins and steel
and individual conciliation is which the moisture within a gas is and cast iron baths, are connected
when there is only one employee released to form water droplets. together through earth bonding so
involved in the dispute. that they are at the same potential
When a gas reaches its dew point, voltage everywhere.
Condensate: the water vapour that the temperature has been cooled
is present in the CO emissions to the point where the gas can Erroneous: wrong; incorrect.
2
resulting from burning gas. As the no longer hold the water and it is European Norm number: a number
flue gases cool down, the water released in the form of ‘dew’, or that shows that something meets
vapour condenses back into water water droplets. not only a British Standard but also
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the European Standard, to ensure in the UK responsible for the Level: when pipework is perfectly
consistency throughout the EU. encouragement, regulation and horizontal.
enforcement of workplace health,
Fire stopped: a barrier is placed Liaise: establish a co-operative
where the pipe passes through a safety and welfare regulations and working relationship.
floor, ceiling or wall to prevent the government legislation. Maintenance: preserving the
spread of fire and smoke. Heat exchanger: a device or vessel working condition of appliances
that allows heat to be transferred
Flashback: where the flame burns and services.
in the torch body, accompanied by a from one water system to another Mandatory: required by law;
high-pitched whistling sound. It will without the two water systems compulsory.
occur when flame speed exceeds being allowed to come into contact
gas flow rate so that the flame with each other. The transfer of Mechanical suction: suction that is
can pass back through the mixing heat between the two systems created by an electrical/mechanical
chamber into the hoses. Most likely takes place via conduction (see pump installed onto a tanker truck.
causes are incorrect gas pressures Chapter 3, Scientific principles). Meter: a display that enables the
giving too low a gas velocity, hose Hertz (Hz): the SI unit of frequency, local company to take readings for
leaks or loose connections. measuring the number of cycles your bill.
per second in alternating current.
Floc: a collection of loosely bound Method statement: the record
particles or materials. These are Immersion heater: an electrical of how management wants the
bound together by the coagulation element that sits in a body of job to be done. Its main purpose
process for easy removal from the water, just like in a kettle. When is to guide site work and it must
water. switched on, the electrical current always be available on-site as a live
causes the electrical element document with an aim to prevent
Foot a ladder: stand with one foot
on the bottom rung, the other to heat up, which in turn heats accidents or dangerous situations
firmly on the ground. up the water. Most immersion from occurring.
heaters elements are rated at 3
Forced draught: the use of a kW but cylinders can have 1, 2, Molecule: the smallest particle of a
purpose-designed fan to create 3 or 4 elements. All immersion specific element or compound that
a positive updraught by forcing heaters must comply with BS EN retains the chemical properties of
the products of combustion up 60335–2–73 and have a resettable that element or compound.
the flue. double thermostat (RDT) as Multi-disciplinary approach:
Fully pumped system: a heating standard. This enables problems using skills from other professions
system that uses pumped with overheating to be recognised or trades to overcome problems
circulation to both heating and hot quickly. outside the normal scope of
water circuits. In situ: in situ, in plumbing your skill set, trade or profession
to reach satisfactory solutions,
Gravity circulation: circulation that terms, simply means pipework or conclusions or outcomes.
occurs because heat rises through appliances that are already in place.
the water. No pump is required. They are already ‘in situation’, Multi-storey: tall building that
hence the term ‘in situ’. requires boosting or pumping of
Grey water: waste water from the water supply pressure given its
baths, showers, washing machines, Legislation: a law or group of height.
dishwashers and sinks. laws that have come into force;
health and safety legislation for Naphtha: a waxy oil deposit that
Hazard: a danger; something that the plumbing industry includes is present in natural gas in its
can cause harm. the Health & Safety at Work unrefined state. It is removed and
Health and Safety Executive Act and the Electricity at Work later reused in other products such
(HSE): the government body Regulations. as cosmetics.
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Glossary
Noggin: a term often used on-site system and the heat exchanger of Sealed heating systems: heating
to describe a piece of wood that an indirect-type hot water storage systems that are sealed from the
supports or braces timber joists cylinder/vessel. It is called the atmosphere and operate under
or timber-studded walls. They are primary water because it is heated pressure. They do not contain a
particularly common in timber by the primary source of heat and feed and expansion cistern. Instead,
floors as a way of keeping the joists hot water in the dwelling, namely they have an expansion vessel to
rigid and at specific centres, but the boiler. The pipes that connect take up water expansion and a
they can also be used as supports the boiler to the heat exchanger filling loop to fill the system from
for appliances such as wash hand are called the primary flow and the the cold water main.
basins and radiators that are being primary return. The secondary water Semi-gravity system: a central
fixed to plasterboard. is the stored water in the cylinder heating system that has pumped
itself that is delivered to the hot
Nominal capacity: (of a cistern) the heating circulation but gravity hot
total volume it could hold when water outlets and taps. The primary water circulation.
filled to the top of the cistern. water heats the secondary water
indirectly via the heat exchanger. Sheath: insulation around the
Overheads: costs that include main copper cable, made from PVC
such things as site offices and staff Prohibit: prevent or forbid by law. plastic.
salaries. Qualitative method: divides Sheeting out: sheeting out a
risks into categories such as low,
Parasitic circulation: circulation tower scaffold means covering
that occurs within the same pipe; medium and high. the outside of the scaffold with
often called one pipe circulation. It Quantitative approach: ranking a tarpaulins. This can be extremely
generally occurs in open vent pipes risk with a number. dangerous as the tarpaulins act like
that rise vertically from the open Rectification: putting something the sails on a ship and could easily
vented hot water storage cylinder. right, correcting. blow the scaffold over.
The hotter middle water rises up Single feed, self-venting indirect
the vent pipe, and the cooler water, Regulatory body: an organisation cylinder: often referred to as the
towards the wall of the pipe, falls set up by the government to ‘Primatic’ cylinder, which is a trade
back to the cylinder. It can be a monitor, control and guide various name of IMI Ltd. Another version
major source of heat loss from hot sectors within industry. of this type of cylinder was also
water storage cylinders. Rippling: an unwanted, wavy available and may be found in
Permitted: being allowed to do pattern made on the inside face of some existing installations. It was
something. a machine bend when the bending known as the ‘Aeromatic’. It is
arm roller is not tight enough. slightly different from the Primatic
Plumb: when pipework is perfectly
vertical. Risk calculation formula: this because it has an air release valve
is a method of using a formula on the side of the cylinder near the
Portable appliance test (PAT test): of multiplying likelihood by heat exchanger to bleed air from
the process of checking electrical consequences to provide a number the heat exchanger.
appliances and equipment to that quantifies the level of risk for a
ensure they are safe to use. Soakaway: a pit, usually 1 m × 1 m
particular job. × 1 m, dug into the ground and
Potable: drinkable, from the French Rosin: a natural solid, resin-type filled with gravel, into which the
word ‘potable’, pronounced material obtained from pine rainwater pipe discharges. It allows
‘poe-table’. rainwater to soak naturally away to
trees, which, when heated, forms
Primary and secondary water: the acidic particles that can irritate the water table. A soakaway should
primary water is the water that the breathing. This could lead to be situated at least 5 m away from
is in the boiler, central heating occupational asthma. the property.
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The City & Guilds Textbook: Plumbing Book 1
Spigot: another name for the plain Throating: a slight indentation that It can also be caused by a faulty
end of a pipe. If the fitting we buy the bending machine makes when washer or diaphragm.
has a plain pipe end, we call this a the bend is formed. Wavering out: the process of water
spigot end.
Toolbox talk: a toolbox talk is an in traps in appliances moving
Stratification: in a hot water informal meeting to deal with with a wave-like motion because
storage cylinder, water forms in matters of health and safety in of pressure fluctuations due to
layers of temperature from the top the workplace and safe working exposure to winds.
of the cylinder where the water is practices. They are normally Wetting: the process of using a
at its hottest, to the base where short meetings conducted on-site flux and solder to join copper
it is at its coolest. Stratification before the commencement of components is often referred to in
is necessary if the cylinder is the day’s work activities. Toolbox the plumbing trade as wetting.
to perform to its maximum talks are an effective way of
efficiency and manufacturers will refreshing operatives’ knowledge Wheel and axle: a mechanical
purposely design storage vessels and communicating the company’s device used to wind up weight;
and cylinders with stratification health and safety culture. includes a grooved wheel, turned
in mind. Designers will generally by a cord/chain, and a rigid axle.
design: Turbidity: the cloudiness or Work programme: a very detailed
haziness of water caused by
l a vessel that is cylindrical in particles that are usually invisible document used on projects to record
shape to the naked eye. Turbidity is a key and assess activity against expected
l a vessel that is designed to be test of water quality. time to complete the project. For
installed upright rather than example, it might highlight that
horizontal Units of power: these are read as poor quality of work and low safety
l a vessel with the cold kWh (kilowatts per hour). standards could apply to someone
feed entering the cylinder Velocity: the measurement of the completing work ahead of schedule.
horizontally. rate at which an object changes It could also demonstrate that very
Temper: the temper of a metal its position. In order to measure it, slow progress on a job would impact
on labour costs. The competence of
refers to how hard or soft it is. we need to know both the speed the plumber is very important and
of the object and the direction in
Tender: to submit a price or which it is travelling. It is measured their performance must be assessed
quotation for a job or contract. carefully.
in metres per second (m/s).
Terminal: the terminal of a flue Water hammer: caused by a rapid Zinc chloride: a corrosive
system is the last section of the flue opening and closing of the float- substance that can cause skin
before the flue gases evacuate to operated valve. As the water nears irritation, burns and eye damage if
the atmosphere. Different boilers the water level in the cistern, the it gets in the eye.
and fuels require different terminals.
ball valve can begin to bounce Zoning: a process where living spaces
Terminal: the entry of the cable to a quickly up and down and from side and sleeping spaces are individually
fixed position where it is known to to side. This causes the noise to controlled via independent time
terminate/fix. travel down the pipework, resulting clocks, room thermostats and
in reverberation or a whining noise. motorised zone valves.
Throat: the inside face.
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Index
20 thread copper tube 328 asbestos 21 blowtorches 57
acceleration 173 disposal 26 boiler cycling 440
access equipment 60–71 removal 26 boiler interlock 444, 489
see also working at height working with 9, 24–6 boiler jigs 327
accidents atmospheric pressure 176 boiler management systems (BMS)
definition 16 atoms 184–5 487–8
first aid 33–42 authority, limits of 210, 219 boilers
major injuries 38–42 automatic air valves 473 batch feed 456
minor injuries 35–8 automatic bypass valves 473–4 cast iron heat exchangers 458
preventing 16–20 backflow 248, 290–309, 419 gravity feed 456
recording 42–3 air gaps 293–301 see also central heating systems;
reporting 6, 42–3 back pressure 294 hot water systems
accumulator 274–5, 327 back siphonage 294–5, 301–2 boiling points 159–60, 168
acetylene (C H ) 21, 51 mechanical devices 302–9 and pressure relationship 393–4
2 2
acrylonitrile butadiene styrene point-of-use protection 292–3 booster sets 267–9, 327
(ABS) 113, 152 whole-site protection 291 replacing pump 340
action and reaction 182 zoned protection 291–2 boreholes 243
active flux see self-cleaning flux balancing central heating systems boss green 108
Acts of Parliament 14 473 boss white 108
actual mechanical advantage bar pressure 159–60, 164, 175 bottled gases 51–8
(AMA) 178 see also pressure see also liquid petroleum gas
adhesion of water 161 batch feed boilers 456 (LPG)
Advisory, Conciliation and Arbitration baths 327, 407, 419, 569–72 Boyle’s law 165
Service (ACAS) 216 installation 602 brass, de-zincification of 156
aeration of water 252, 447 behaviour policy 209 break cisterns 287
Aga-type cookers 456 Belfast sink 574 bricklayers 203
air, principle applications 163 benchmarking 141 British and European Standards 211
air admittance values (AAVs) 222, bending pipes BS 1010 316–17
557 90° 105 BS 1212 313
air infiltration 480–1 copper tube 91–7 BS 1566 362
air spa baths 571–2 by heat 105 BS 1710 310–11
airlocks 329, 429 hydraulic machine 105 BS 5412 317–18
alloys 151 low carbon steel pipe 105–7 BS 6465–2:1996 574
alternating current (AC) 187, 645–6 machine bending 91–5 BS 6700 256, 352
aluminium 151 off-set bends 92–3, 96, 106–7 BS 7671 46, 352
amperage 186 passover bends 93–5 BS 8000 595, 596
annealing 84 pipe gain 95 BS 8558 352
anodic corrosion 370 plastic pipe 111–12 BS EN 806 254, 255–6, 352,
anodising 159 spring bending 95–7 411–12
anti-gravity valves 474 Bernoulli’s principle 176–7, 381 BS EN 1491:2000 395
appliance testing 6, 46–9, 225 bib taps 316 BS EN 8558 254, 255–6
approved codes of practice (ACOPs) bidets 327, 408, 419, 568–9 BS EN 12056:2000 526, 533,
14–15 bi-flow mixer taps 316 550, 594–5, 596
aquifers 243 biomass fuel 627, 635–6 central heating systems 440
arbitration 216 black water 252 ear protection 30
architect 199–200 blackheart fittings 107 electrical installations 46
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The City & Guilds Textbook: Plumbing Book 1
guttering 522, 533 controls 483–91 chasing walls 123–4, 653
hot water systems 352 corrosion protection 480–2 chemicals 21–6
sanitary systems 595 decommissioning 515–16 chipboard screw 131
water supply 255–6 district heating installations 163, chisels 78–9
British Standard Pipe (BSP) 85 436, 627 chlorinated unplasticised polyvinyl
British Standard Pipe Threads electric storage heaters 436 chloride (CuPVC) 113,
(BSPT) 85 expansion and contraction 506 152, 328
buffer tanks 479 filling 508–10 chrome plating 159
building control inspector 205 filling loop 477, 503–4 circuit breaker 650
building control officer 201 flue systems 464–6 circuits see electrical circuits
Building Regulations 2010 643–4 fuel types 464, 504–5 circular saw 87
Building Regulations 2013 11–12, fully pumped systems 437, circulating pump 447–8, 503
141, 256 443–51 replacing 510
Building Regulations Approved gas boilers 457–61 cisterns 149, 152, 173–5, 230,
Document G3 2010 heat emitters 467–72 249, 277–9, 327
346–7, 394 installation 506–10 feed and expansion 361, 448,
building services low loss headers 478–9 503
definition 12 maintenance 510–14 civil engineer 200
drawings 206–7 mechanical components 472–80 cleaner’s sinks 573
legislation 12–13 microbore system 452–3 cleaning agents 21
building surveyor 200 oil-fired appliances 461–4 clerk of works 201
burns 36 operating principles 436–8 client 199
bushes 108 power flushing 513 domestic 11
butane 624 programmers 484–5 as duty holder 10, 13
butler’s sinks 573 releasing air from 504 see also customer
buyer 202 reversed return system 453–4 clipping distances 128–9
cables solid fuel appliances 455–7 incorrect 425
concealed 46 temperatures 437 see also pipe clips
in electrical systems 653–4 testing 507–9 coach bolts 131
protection methods 653–4 thermostats 485–6 coach screw 131
canals 243 time clocks 484 coal 625–6
cap ends 103–4 underfloor systems 491–502 coefficient of linear expansion 170
capacitance 184 warm air systems 471, 491 coefficient thermal conductivity 169
capillary attraction 161 wet systems 436–8, 461 coke 626
capillary fittings 98–9 combination boilers 437, 459 cold water accumulators 371–2, 379
carbon dioxide 164 low pressure open vented cold water systems
cardiopulmonary resuscitation 438–49, 505, 508 commissioning 330–1
(CPR) 40–1 sealed pressurised 449–51, connecting bathroom equipment
carpenters 204 506, 510 327–8
cartridge fuses 651 zoning 445, 496–8 decommissioning 340–1
cast iron heat exchangers 458 centre of gravity 181 existing systems 327–8
caustic soda 21 ceramic disc taps 317–18, 337 installing 311–28
celsius 166 ceramic tiles 153 maintenance 331–9
central heating systems ceramics 153 materials 323
balancing 474 certificate of compliance 611 multi-storey buildings 264–9,
buffer tanks 479 cesspits 591–2 283
circulation of water 437 chamfer 114 preparation 328
common faults 513–14 charge, electrical 184 private water supplies 270–4
Charles’s law 165
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Index
storage cisterns 277–80 protecting public 18–19 cyanide 21
supply 261–9 responsibilities 219–21 cylinders
testing 328 visitors 206 grades of 369
collapsing cavity fixings 132 Construction Skills Certification insulating 368–9
combination boilers 382–3, 437, 459 Scheme (CSCS) card 218 see also hot water systems
combined cooling, heat and power consumer units 652–3 Data Protection Act 2018 211
(CCHP) 628 continuity testing 660–1 dead leg 387
combined heat and power (CHP) contract of employment 209 de-alloying 156
627–8 contractors 11, 14 decommissioning 142
combined primary storage unit 384 contractor’s certificate 611 central heating systems 515–16
combustion 58–9 contracts manager 202 cold water systems 340–3
commissioning 141 Control of Asbestos Regulations guttering systems 544–5
cold water systems 330–1 2006 9 hot water systems 427–8
hot water systems 420, 424–7 Control of Lead at Work Regulations sanitary systems 612–14
sanitary systems 606–9 2002 8–9 decorators 204
communication Control of Substances Hazardous degradation of plastics 158
customer 217–18 to Health (COSHH) delegation 223
verbal 213–14 Regulations 2002 2, 5–6 delivery note 207
written 208–9, 212 convection 170 delivery of materials 223
competent persons 7 cookers, Aga-type 456 density
composite valves 400–1 copper, origin of 151 common conductors 188
compression fittings 99–100, 103, copper nails 130 gases 623–4
109, 110 copper tube kerosene 162
compressive strength 154 20 thread 328 water 160
concealed cables 46 bending 90–8 deposition 168
condensation 167 clipping distances 128 dermatitis 615
condensing boilers 458, 460–1 conduction 169 designers 11
conductance 185 fittings 98–104 dew point 460
conduction 169–70 jointing 97–104 de-zincification 156
conductivity 155 pipe clips 126–8 digital thermometers 167
electrical 188 red band 328 direct current (DC) 187, 644–5
conductors 169 testing 139 Distribution Network Operator
density of 188 core drills 91 (DNO) 651
insulation resistance 661–2 corrosion 151, 155–7, 370 district heating installations 163,
size of 654 preventing 159, 480–2 436, 505, 627
conduit 653–4 corrosive substances 21 documentation
Confined Spaces Regulations 1997 9 countersunk screw 131 company policies and procedures
confined spaces, working in 72–4 couplings 103, 108 209
conflicts 215–17 craft operatives 203–4 customer care 208–9
connectors 103–4 crimping 88 on-site 206–10
Construction (Design and cross-connection, preventing 310–11 Domestic Building Services
Management) (CDM) current 183, 185–7 Compliance Guide 352–3
Regulations 2015 10 customer domestic clients 11
construction site care charter 208 domestic installations 118–29
documentation 206–10 handover 142, 209 drain valves 475
inspectors 204–6 information 209 drain-off valves 313
job roles 200–4 liaison 118–19 draught 464–6
management team 197–201 service 119 dress code 209
perimeter fencing 18 cuts 35–6 drill bits 88–9
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The City & Guilds Textbook: Plumbing Book 1
drilling 122–3, 324 Electricity at Work (EAW) open-vented hot water systems
ductility 154 Regulations 1989 6–7 428–9
dust 21, 29 electricity supply 44–5, 644–51 feed and expansion cistern 448,
duty holders 7, 10, 13 earthing systems 648 503
see also employer duties isolation procedure 49–51, ferrous metals 151
dynamic pressure 176 659–64 ferrous oxide 155–6
earthing 7, 193–4, 648 electrolyte 156–7 fibreglass 21
elbows 103, 108 electrolytic corrosion 481–2 files 85
electric cable 44 electromotive force (EMF) 188 filling loop 477, 503–4
electric shock 40, 43–4, 665 electron flow 184–5 filters, drinking water 322–3
electric storage heaters 436, 505 emergency maintenance 333 filtration 250–2
electrical employee responsibilities 3, 13 final fix 134
circuits 185–6, 190–4, 647 employer duties 2–5, 7, 13, 34–5 fire
conductivity 155, 188 employment contract 209 classes of 59
equipment 4, 6–7, 46 end feed 98, 103 combustion 58–9
flow 185–7 energy equipment signage 20
hazards 43–9 calculations 171–2 extinguishers 59–60
installations 45–6 efficiency 354 fighting 60
resistivity 188 unit of measurement 166 safety 58–60
electrical components 651–8 engineers 200 fireclays 153
faults 664–5 Environment Agency 241 firestopping pipework 138
electrical services inspector environmental impact 354 first aid 33–42
205–6 equal tees 103, 108 burns 36
electrical systems Equality Act 2010 210–11 cardiopulmonary resuscitation
documentation 643–4 equilibrium 182–3 (CPR) 40–1
protection methods 650–1 equipment cuts 35–6
spurs 655–7 electrical 658–9 electric shock 40
testing procedures 659–60 hand tools 77–86 exposure to fumes 37–8
wiring 653–4 health and safety 85–6, 88–9 fractures 38–9
see also electricity supply power tools 88–90 objects in eye 36–7
electricians, job role 204 storing 124–5 recovery position 41–2
electricity equipotential bonding 50–1, 194 unconsciousness 39–40
alternating current (AC) 187, erosion corrosion 157 first fix 133–4, 224
645–6 estimates 208 fittings
amperage 186 estimator 202 capillary 98–9
capacitance 184 European Norm number 643 compression 99–100, 103, 109,
charge 184 evaporation 167 110
conductance 184 excavations 72–4 connectors 103–4
current 183, 185–7 expansion vessels 396–400, couplings 103, 108
current and fuse size 651 475–6, 499 elbows 103, 108
direct current (DC) 187, 644–5 exposure to fumes 37–8 end feed 98, 103
electrical flow 185–7 eyes equal tees 103, 108
Ohm’s law 186, 188–90 objects in 36–7 fusion-welded 111
power 186 protection 28–9 integral solder ring 98, 103
principles of 184–90 Fahrenheit 166 malleable iron 107–8
resistance 184, 186 fan convectors 471 manifolds 103–4
units of measurement 183–4, faults press-fit 101–2, 103
185–6 central heating systems 513–14 proprietary 117
voltage 183, 185–6
674
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Index
push-fit 100–1, 103, 110, galvanic corrosion 156–7 hazards 1, 16–20, 43–9, 228
112–15, 117 galvanisation 159 HDPE (high-density polyethylene)
recognition 103 galvanised clout nails 130 152, 328
reducers 103 Gantt chart 207 health and safety
soil pipes 115–16 gas 454 drainage systems 614–15
steel 107 see also (liquid petroleum gas) electrical equipment 46–9
waste pipes 116–17 LPG; natural gas equipment 85–6, 88–9
fixings 129–33 gas boilers 457–61 fuel storage 638–9
flammable substances 21 gas fitters 204 hazards 1, 16–20, 43–9, 228
flashback 53 Gas Safe 352, 631 heat-producing equipment 51–6
flashback arrestor 53 Gas Safety (Installation and Use) inspector 15, 205
flex cables 653 Regulations 1998 12, 352 legislation 1–15
flexible connectors 103 gas seal paste 108 risk assessments 17–18, 222,
float operated valves 314–15 gas thermometer 167 227–33
float switches 276 gases Health and Safety at Work etc. Act
float-operated valves 339 air 163 (HASAWA) 1974 2–3, 20
floc 251 Boyle’s law 165 Health and Safety Executive (HSE)
floor brads 130 carbon dioxide 164 10, 15
floorboards, lifting 119–21 changing states of 167–8 Health and Safety Executive/Local
flow rate 173 Charles’s law 165 Authorities Enforcement
factors affecting 177–8 latent heat 168 Liaison Committee
hot water systems 423 laws of 164–5 (HELA) 15
flue systems 464–6 sensible heat 168 Health and Safety (First Aid)
fluid categories 242–5, 290 specific gravity 150 Regulations 1981 (with
flushing hot water systems 422–3 steam 163 2013 amendment) 9
fluxes glass thermometer 167 health and safety inspector 15, 205
self-cleaning 23, 100 gloves 30
traditional flux paste 99 glycol 162 hearing impairment 213
wetting 23 graphite paste 108 hearing protection 30
working with 21, 23 gravity heat
see also jointing centre of 181 calculations 171–2
footwear 28 force of 173–4 emitters 467–72
force, unit of measurement 173–4 gravity circulation 170, 437 exchangers 361–2, 458–9
forced draught 464–5, 466 gravity distribution 253 flow 166–8
fractures 38–9 gravity feed boilers 456 latent 168
Freedom of Information Act 2000 211 grey water 246–7, 290, 617–19 pumps 627–8
freezing 168 grips 81 sensible 168
freezing point 160 guttering 521–46 thermal degradation 158
frictional resistance 178 hammers 78 transfer 169–71
frost protection, cisterns 288 hand tools 77–86 unit of measurement 166
fuel oils 162 handover information 142, 209 heat-dissipating spray gel 138
fuel systems 630–9 handsaws 80–1 heat-producing equipment 51–6
fuel types, central heating systems hard hats 27–8 heat-resistant cables 653
454, 504–5 hardness of materials 154 height, working at 7–8, 60–71,
fully pumped central heating hawk white 108 533–4
systems 437, 443–51 hazard symbols 229 hematite paste 108
fumes 29 hazardous substances Hep2O 113
exposure to 37–8 health and safety 2, 5–6 hepatitis 615
fuse boxes 652–3 identifying 20–1 hertz (Hz) 187, 645
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The City & Guilds Textbook: Plumbing Book 1
HETAS (Heating Equipment Testing statutory regulations 346–53 positioning pipework 126–9,
and Approval Scheme) storage cylinders 368–9, 135–7
631 376–80 preparation 119–24
high-density polyethylene (HDPE) testing 420–4 pre-testing checks 139
109 thermal stores 383–4 private houses 118–29
high-necked pillar taps 316 thermostatic mixing valves protecting surroundings 138
hole saws 90 (TMVs) 407–11, 413 second fix 134
horseplay 3 tundish arrangements 400–1 shower mixing valves 414–19
hose union bib taps 316 unvented 372–80, 387, 401–6 snagging 134
hot water systems hot work 52–8 temperatures 408, 412
centralised 356–86 hydraulic bending machine 105 testing 139–40
cold water accumulators 379– hydraulic low carbon steel bending instantaneous water heaters 381–2,
80 machines 87 384
combination boilers 382–3 hydrochloric acid 21 insulation
combined primary storage unit ice 167–8 cisterns 288–9
384 ideal mechanical advantage (IMA) hot water pipework 413
commissioning 420, 424–7 178 insulation resistance 661–2
components 392–3 immersion heaters 360–1, 412, integral solder ring 98, 103
decommissioning 427–8 428 invoices 208
discharge pipework 400–5 imperial units 148 iron 151
efficiency 405 improvement notice 15 irritant substances 21
energy efficiency 354 in situ working 137–8 isolating electricity supply 49–51,
expansion vessels 396–400, individual conciliation 216 659–64
475–6, 503 isolation valves 311–13
factors affecting 353–5 induced siphonage 584–5 jig saw 87
infrared thermometers 167
faults 428–9 job roles 200–4
flow rate 423 injuries job specifications 206, 223
flushing 422–3 acute 31 joiners 204
functional controls 395–401 chronic 31 jointing
initial system fill 421–2 eyes 28–9 capillary fittings 98–9
installation 411–20 major 38–42 compounds 108
instantaneous heaters 381–3, minor 35–8 compression fittings 99–100,
384 reporting 6, 42–3 103, 109, 110
insulation 413 see also accidents; first aid copper tube 97–104
localised 386–7 in-line strainer 396 fittings 107–8
manufacturer’s technical inspectors 204–6 low carbon steel pipe 107–9
instructions 353 installations plastic pipe 110–11, 112–17
noise in 429 benchmarking 141 press-fit fittings 101–2, 103
open vented 356–72, 384, 389, Building Regulations compliance push-fit fittings 100–1, 103,
407 141 110, 112–15, 117
overheating 429 central heating systems 506–10 solvent weld joint 114, 116
renewable energy supply 357 commissioning 141 threaded joints 107
safety 406–11 decommissioning 142 joists, notching and drilling 121–3
safety controls 393–5 final fix 134 junction boxes 656–7
secondary circulation 387–92, first fix 133–4 kelvin scale 166–7
424 handover to customer 142 kerosene 162, 625, 632–4
selecting 355 hot water systems 411–20 kick-space heaters 471
solar thermal 384–6 making good 124–5 kinetic energy 165
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Index
kinetic lifting 31–2 lockshield valves 473 hardness 154
kitchen sinks 408, 419, 573–4 low carbon steel pipe malleability 154
ladders 62–6 bending 105–7 metals 150–1
classification 61–2 clipping distances 128 oxidation 155
raising and lowering 64 grades 104–5 plastics 152
securing 64–5 jointing 107–9 principle applications 150–3
see also working at height testing 139 properties of 150, 153–5
language differences 214–15 low pressure open vented central sanitary systems 597
latent heat 168 heating systems 438–49, shear strength 154
lead 505, 509 tensile strength 153
origin of 151 low surface temperature radiators matter, states of 167–8
pipes 328 (LSTs) 470 MDPE (medium-density
working with 8–9, 21–3 low water content heat exchangers polyethylene) 152
lead-free solder 98–9 458–9 mechanical lifting aids 33
leadlocks 117 lubricants 163 mechanical principles 178
leakage 329–30, 425 machine bending 92–6 action and reaction 182
Legionella 409, 425 magnesium rods 159 actual mechanical advantage
legislation magnetic filters 482 (AMA) 178
approved codes of practice maintenance 142–3, 222–3 centre of gravity 181
(ACOPs) 14–15 central heating systems 517–18 equilibrium 182–3
building services 12–13 cold water systems 331–9 ideal mechanical advantage
construction industry 10–11 emergency 333 (IMA) 178
data protection 211 sanitary systems 615–17 levers 178–9
enforcement 15 taps 333–9 Newton’s third law of motion
equality 210–11 making good 124–5 182
freedom of information 211 malleability 154 pulleys 179–80
guidance notes 15 mandatory safety sign 20 screw machine 180
health and safety 1–15 manganese paste 108 torque 179, 181
levers 178–9 manifolds 103–4 wheel and axle 179
lifting and handling techniques manipulative compression fittings mechanical suction 592
31–3 100 mediation 216
light, photodegradation 158 manual handling 31–3 medium-density polyethylene
limits to personal authority 210, 219 mechanical lifting aids 33 (MDPE) 109–10
linseed oil-based compounds 108 one-person lift 31–2 melting 167
liquid petroleum gas (LPG) 21, two-person lift 32–3 metals 150–1
51, 56–8, 163, 623–4, Manual Handling Operations conductivity 155
634–5 Regulations 1992 8, 31 corrosion 155–7, 159
liquids manufacturer’s instructions 256 oxidation 155
changing states of 167–8 MAPP (methylacetylene-propadiene meters 652
glycol 162 propane) gas 51 method statement 18, 233–5
kerosene 162 masonry nails 130 microbore system 452–3
latent heat 168 materials mild steel pipe see low carbon steel
lubricants 163 ceramics and fireclays 153 pipe
properties of 159–63 compressive strength 154 minerals 154
refrigerants 161–2 conductivity 155 mirror screw 131
sensible heat 168 corrosion 155–7, 159 mixer taps 316
see also water degradation 158 mobile elevated working platforms
local authority 201 delivery of 223 (MEWPs) 71
localised hot water systems 386–7 ductility 154 Mohs scale 154
677
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motorised valve failure 429 permits to work 18, 52 plastic pipe
multifunction meters 659 personal protective equipment (PPE) bending 111–12
multi-storey buildings, cold water 2, 4, 27–30 clipping distances 128–9
systems 264–9, 283 Personal Protective Equipment jointing 110–11, 112–17
nails 130 (PPE) at Work Regulations polybutylene (PB-1) 111–13,
natural draught 465 1992 2, 4, 28 129, 152, 328
natural gas 163–4, 504, 623 petrol 21 installation 134–5
newtons (N) 174 pH value of water 160–1 testing 139
Newton’s third law of motion 182 Philmac fittings 117 polyethylene (PE) 109–10, 152
nipples 108 photodegradation 158 polypropylene (PP) 116–17, 152
noggin 131 physical disabilities 213–14 polyvinyl chloride (PVC) 113–17
noise 329, 429 pillar taps 316–17 properties 109–11
hot water systems 424–5 pipe clips 126–9, 135 plastic wall plugs 132–3
non-condensing boilers 458–9 pipe freezing kits 88 plastics 152
non-ferrous metals 151 pipe gain 95 degradation of 158
non-manipulative compression pipe materials see copper tube; pliers 82
fittings 99–100, 112 low carbon steel pipe; plugs 657–8
non-return valves 53, 396–7 plastic pipe wiring 658
non-rewireable plugs 651 pipe threading machines 88 plumbers, job role 204
notching 121–2, 324–5 pipe-bending tools 84 polarity testing 660–1
off-set bends 92–3, 96, 106–7 pipe-cutting tools 83 policies and procedures 209
OFTEC (Oil Firing Technical pipework policy documents 207
Association) 631 access to 598 polybutylene (PB-1) 111–13, 129,
Ohm’s law 186, 188–90 colour coding 310–11 152, 328
oil 454, 504, 625, 632–4 expansion and contraction 414, installation 134–5
oil-fired appliances 461–4 429, 505, 608–13 testing 139
olive ring fittings 99–100 firestopping 138 polyethylene (PE) 109–10, 152
on-site trades 203 insulation 413 Polyplumb 113
open vented hot water storage noisy 329 polypropylene (PP) 116–17, 152
systems 356–72, 381, open vented hot water systems polyvinyl chloride (PVC) 113–17
389, 407 367–72 portable appliance test (PAT) 6, 46–9
faults 428–9 positioning 126–9, 135–7, portable power tools 46–9
oval bright wire nails 130 324–5 potable water 152, 242, 258
overalls 28 prefabrication of 135–7 power, unit of measurement 166,
overflow 282–4 sleeving 137 652
oxidation 155 in suspended timber floors power drills 87
oxidising substances 21 324–5 drill bits 89–90
oxyacetylene 51 unvented hot water systems power flushing 513
bottle set 53–6 376, 401–5 power tools 87–90
torches 105 in walls 325 pre-installation preparation 119–24
oxygen (O 2 ) 51 waste pipes 551–9, 597 press-fit fittings 101–2, 103
parallel circuits 192–3 pitcher tees 108 pressure
parallel threads 107 pitting corrosion 157 atmospheric 176
parasitic circulation 357 planning engineer 202 Bernoulli effect 176–7
pascal (pa) 164 planning officer 201 calculations 174–5
passover bends 93–5 plant manager 202 dynamic 176
peat 626 plaster, patching 124 gases 164
performance monitoring 227 plasterboard fixings 131–2 siphonic action 176–7
perimeter fencing 18 plasterers 204 unit of measurement 173, 175
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Index
water 175 rawlbolts 131 existing bathroom refurbishment
pressure reducing valves (PRVs) 396 rawlplugs 132–3 604–5
pressure regulator 53 reciprocating saw 87 health hazards 614–15
pressure relief valves 400, 477, 503 recovery position 41–2 installation 594–605
pressure-compensating mixing red band thin wall copper tube 328 layout specifications 573–4
valves 319–20 reducers 103 maintenance 615–17
primary ventilated stack system reducing tees 103–4 primary ventilated stack system
550–4 refrigerants 161–2 550–4
principle contractors 11, 14 relative density 150 secondary ventilated stack
principle designer 11, 13–14 renewable energy hot water systems system 555
private water supplies, cold water 357 sub-stack system 556
systems 270–4 Reporting of Diseases and Dangerous testing 606–9
Private Water Supply Regulations Occurrences Regulations ventilated branch discharge
2016 255 (RIDDOR) 1995 6 system 554–5, 557–8
programmers, central heating residual current breakers with waste pipework 551–9, 575–83,
systems 484–5 overload protection 597
progress chart 224 (RCBOs) 651 scaffolding 66–71
prohibition notice 16 residual current device (RCD) 45, scaling reduction 321
prohibition safety sign 19 650 screw down stop valve 256–7
propane (C3H8) 51, 56, 624 resistance, electrical 184–6 screw machine 180
proprietary fittings 117 respiratory protective equipment screwdrivers 77–8
prosecution 16 (RPE) 29–30 screws 130–1
protective equipment see personal reversed return system 453–4 sealants 21
protective equipment (PPE) rewireable fuses 650 sealed pressurised central heating
Provision and Use of Work rippling 84, 94 systems 449–51, 505,
Equipment Regulations risk assessments 17–18, 222, 510
(PUWER) 2009 4 227–33 second fix 134, 224
public, protecting 18–19 risk calculation formula 230–3 secondary circulation 387–92, 424
pulleys 179–80 river water 241 secondary ventilated stack system
pumped distribution 253 room heaters 455 555
pumps, shower 320 rosin 23 sedimentation 249
pure metals 151 round bright wire nails 130 self-cleaning flux 99
push-fit fittings 100–1, 103, 110, round head screw 131 self-drill plasterboard fixings 132
112–15, 117 rubber nut fixings 132 self-siphonage 584
quantity surveyor 200 rusting 155–6, 159 sensible heat 168
‘quick recovery’ cylinders 370 sacrificial anodes 159 septic tanks 592
quotations 208 safe condition sign 20 series circuits 190–2
radiation heat transfer 171 safety helmets 27–8 shear strength 154
radiator spanner 86 safety signs 19 showers 407, 572–3
radiators 171, 467–72 Safety Signs and Signals Regulations boosting pumps 414–15
dressing 470 1996 8 group 409
hanging 132–3, 467–9 sanitary systems mixer valves 318–20, 414–19
replacing 510–11 appliances 559–78, 600–1 pumps 320
rainfall 526–7 below-ground drainage 588–94 SI system 147–9, 154, 164, 166,
rainwater cycle 238–40 blockages 616–17 173
rainwater harvesting 247–9, 290, certification 609–11 base units 148
617–19 commissioning 606–9 conversion tables 148–9
rainwater systems 520–46 decommissioning 612–14 derived units 148
rasps 85 dressing appliances 600–1 signage
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hazards 229 stop taps 311–13 temporary continuity bonding 50–1,
health and safety 18 stop valves 256–60 650
legislation 8 storage cisterns 277–90 tender 224
single check valves 396–7 storage cylinders 368–71, 376–81 tensile strength 153
sinks see kitchen sinks storing, tools and materials 125–6 tension test 153
siphonic action 176–7 strap boss installation 598 terminal fittings see taps
site management team 197–201 stratification 415 testing
site supervisor 202 strength, of sold materials 153–4 central heating systems 507–9
site visitors 206 structural engineer 200 cold water systems 328
skirting heating 472 subcontractors 14, 202 guttering systems 545–6
sleeving pipework 137 sublimation 168 hot water systems 420–4
snagging 134 submersible pumps 274 thermal
soakaways 590–4 sub-stack system 556 conductivity 155
soil pipes 115–16 sulphuric acid 21 degradation 158
solar thermal hot water systems sunlight, UV degradation 158 expansion 535–6
385–6 supervision 219–21 radiation 171
solar thermal radiation 171 surface pumps 272–4 stores 383–4
solar thermal technology 627 surface tension 161 thermistor 167
soldering surveyor 200 thermocouple 167
equipment 84 sustainable fuels 627 thermo-mechanical cylinder control
lead-free solder 98–9 swarf 85 valves 474–5
protecting surroundings 138 symbols, hazards 229 thermometers 167
see also jointing tank connectors 103–4 thermoplastic (PVC) cables 653
solid fuel 454, 505, 625–7 tap hole arrangements thermoplastics 152
appliances 455–7 baths 569–71 thermosetting 152
solidification 168 washbasins 566–8 thermostat failure 428
solvent weld adhesives 21 tapered threads 107 thermostatic mixing valves (TMVs)
solvents 21, 23 taps 315–18 320, 407–11, 413
spanners 79–80 ceramic 317–18, 337 thermostatic radiator valves (TRVs)
special learning needs 214 connectors 103–4 474
specific gravity 150 leakage from 330 thermostats
specific heat capacity 160 maintenance 333–9 central heating systems 485–6
unit of measurement 166 noise 329 hot water systems 394–5
water 171–2 non-rising spindle 317 threaded joints 107
Speedfit 113 replacing 337–9 threading equipment 84–5, 88
spigot 114 re-seating 86, 333–7 throating 84, 94
spirit levels 82 re-washering 33–6 tilers 204
spring bending 95–7 rising spindle 316–17 time clocks 484
spring loaded toggle bolts 132 temper 89 time sheets 207
spring water 241 temperature timekeeping 209
spurs 655–7 central heating systems 437 tin 151
stagnation, prevention of 281 gases 164–5 TN-C-S system 649
stainless steel tube 328 hot water systems 393–5 TN-S system 648–9
states of matter 167–8 installation 407–8, 412 toolbox talk 227
static head of water 175 sensors 277 tools and equipment see equipment
statutory cancellation rights 208 thermometers 167 torque 179, 181
steam 163, 167 units of measurement 166–7 towel warmers 471
stepladders 60–1 temperature relief valve 407 tower scaffolds 66–8
sterilisation 252 templars paste 108 toxic substances 21
680
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Index
see also hazardous substances wall plugs 132–3 supply 245–50, 329
trade supervisor 202–3 walls, cutting chases in 123–4 unwholesome 246–7
transducers 277 warm air systems 471, 491, 505 see also cold water systems
traps 575–83 warning safety sign 19 Water Act 2003 245–6, 255
trenches 72–4 washbasins 327, 407, 408–9, 419, water hammer 315
trunk mains 256 565–8 Water Industry Act 1991 242,
trunking 654 installation 602–3 245–6
TT system 648 washers water inspector 205
tubular scaffolds 69–71 faulty 329 Water Supply (Water Fittings)
tundish arrangements 400–1 see also taps Regulations 1999 12,
turbidity 249 waste arrangements 98, 242, 246, 254–5,
type A compression fittings 99– baths 570–4 259, 288–9, 310, 325,
100, 112 shower trays 572 347–51, 395, 595
type B compression fittings 100 washbasins 566–8 water undertaker’s notification
unconsciousness 39–40 waste disposal units 577–8 609–10
underfloor central heating systems waste pipes 116–17 watt 166
491–502 waste traps 575–83 WCs 560–5
unions 108 water blockages 617
unplasticised polyvinyl chloride adhesion and cohesion 161 connecting to cold water system
(PVCu) 113, 152 aeration of 447 327
unsintered polytetraflourethylene black 248 installation 603–4
(PTFE tape) 108 boiling points 159–60, 168 macerators 576
unvented hot water storage systems capillary attraction 161 weather compensation controls
372–80, 387 categories 242–5, 290 486
unwholesome water 246–7 changing states of 167–8 Weil’s disease 614
upland surface water 240 conditioners 321–2 welding 54–8
urinals 574–6 density 160 wells 240
UV (ultra violet) degradation 158 distribution 253, 256 wetting 23
valves filters 322–3 wheel and axle 179
drain-off 313 filtration 250–2 wheel head valves 472
float operated 314–15 freezing point 160 whirlpool baths 571–2
isolation 311–13 grey 246–7, 290, 617–19 whiteheart fittings 108
shower mixer 318–20 leakage 425 wiring
vaporisation 167 main 257–9 in electrical systems 653–4
vapourising burners 463–4 meter 259 a plug 658
variation order 225–6 pH value 160–1 Work at Height Regulations 2005
variations in work 225–6 potable 152, 242, 258 7–8
velocity 173 pressure 175, 379, 393–5 work programme 207, 221–2
ventilated branch discharge system properties of 159–61 working at height 7–8, 60–71,
554–5, 557–8 rainwater cycle 236–8 533–4
venturi boost mixing valves 319 scaling 321 working drawings 206–7
verbal communication 213–14 sedimentation 249 wrenches 81
visual impairment 212 softeners 322–3 written communication 208–9, 212
vitreous china 153 sources of 240–1 zinc 151
voltage 183, 185–6 specific heat capacity 171–2 zinc chloride 23
colour coding 45 steam 160 zoning central heating systems 445,
volume, gases 164 sterilisation 252 496–8
681
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The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)
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