DCC50252- Notes

Lead sheathed or metal sheathed wiring

The type of wiring employs

conductors that are insulated

with VIR and covered with an

outer sheath of lead aluminum

alloy containing about 95% of lead

The metal sheath given protection

to cables from mechanical

damage, moisture and

atmospheric corrosion.

Lead sheathed or metal sheathed wiring

Advantages disAdvantages

It is easy to fix and look nice In case of insulation damage, the
Can be used in damp metal sheath become alive and
condition may cause electrical shock
It can be used in situations Not suitable installation at places
that exposed to sun and where chemical corrosion may
rain occur
It provides protection Skilled labor and proper
against mechanical injury supervision required upon
It has long life span if proper installation
continuity is well maintain It is costly compare to TRS wiring

Conduit wiring system Surface
Conduit
Wiring system is more secure Wiring
than other wiring system because
they can provide good mechanical
protection and durability
There are two types of conduit
namely metal (GI) and PVC type
It is also composed of several sizes
including 16mm, 20mm, 25mm and
32mm.
2 types of PVC conduit installation:-

Surface Conduit Wiring
Concealed Conduit Wiring

Conduit wiring system

Advantages disAdvantages

It provides protection against It is very costly system of
mechanical damage. wiring.
It provides complete protection Its' erection is not easy
fire due (GI Conduit) to short and required time.
circuit. Experienced and highly
The whole system is waterproof. skilled labour is required
Replacement and alteration of for carrying out the job
defective wiring is easy.
Its life is long.
It is shocked proof also if
earthing is properly done.

1.List 6 factors to be
considered in selecting the
wiring system

2. Name 5 types of wiring system

THANK YOU

DCC50252:
BUILDING
SERVICES

MDM ADILEN @ LUCIA BT SUIL

Lecturer

Dept. of Civil Engineering, POLISAS

1.2 Recognize 3 methods
ELEMENTS IN of electrical wiring
ELECTRICAL Identify the usage of
fitments and their
WIRING function in the
electrical wiring
Explain the standard
symbols in the wiring
system by using
suitable graphic aids

ELECTRICAL WIRING WHAT IS
ELECTRICAL

WIRING?

Electrical wiring is an
electrical installation of
cabling and associated
devices such as switches,
distribution boards, sockets,
and light fittings in a structure.

Factors of wiring's selection:

1 Durability 4 Low initial Cost

2 Safety 5 Accessibility
3 Appearance
6 Low maintenance

cost

1.2.1

TYPES OF
WIRING

3 METHODS OF WIRING

Surface @ Open Wiring 1

2 Conceal @ Hidden Wiring

Conduit Wiring 3

Surface @ Open Wiring

It is a exposed type of wiring, that
is visible on the walls or ceiling
Are used to extend electric
current and power from existing
outlets or fixtures to a new
location
It need not to tear up floors or cut
into walls or ceilings
Standard 120-volt wires are
installed in metal (GI) or plastic
(PVC) channels (raceways)

Surface Wiring

Advantages disAdvantages

It is cheap wiring There is a high risk of fire in
system casing & capping wiring
Damage can be system.
easily detected Not suitable in the acidic,
The addition alkaline and humidity
does not involve conditions
the entire wiring Do not have mechanical
protection
Not durable
Exposure to chemical hazards,
insect and animal bites

Concealed Wiring System

Conduits are hidden inside the saddles
wall slots or chiseled brick wall
Electrical wires are laid inside
the conduits.
This type of wiring cable types
use two layers of copper-
coated PVC (PVC / PVC).
Tin clips (saddles) used for
gripping the cables are
formed

Concealed Wiring System

Advantages disAdvantages

It is a safe wiring system Expensive
Safe from chemical effects, Changing the location of
humidity and other external switches or appliances is
factors difficult
No risk of shock Installation is complex
It is aesthetically appealing Hard to find defects in the
No risk of wear and tear, fire or wiring
damaged cable insulation Adding additional conduit in
Quite reliable future is a tedious task
Renovations can be easily
performed as you can replace
old wires easily

Conduit Wiring System

Conduits are used to protect and
provide route of electrical wiring in
electrical system.
These conduits are made of plastic
(PVC), metal (G.I) or fiber.
It can be rigid or flexible.
It provides protection and safety
against fire
Has several sizes including 16mm,
20mm, 25mm and 32mm.
During the installation work conduit
used some special tools.

7 Types of Electrical Conduit

Rigid Metal Conduit (RMC Intermediate Metal Conduit Electrical Metalic Tubing (EMT) Electrical Non-Metallic
(typically used outdoors) (IMC) (For exposed indoor wiring) Tubing (ENT)

(For new outdoor (typically used inside walls)
construction projects)

Liquid-Tight Flexible Metal Flexible Metal Conduit Rigid Polyvinyl Chloride
Conduit (LTFM) (FMC) (Rigid PVC)

(typically used with (For dry indoor locations) (For corrosive
outdoors equipment) environments)

Conduit Wiring System

Advantages disAdvantages

Durability To make tread, bend and
Providing good mechanical make 'off set' requires
protection. special tools.
Provide additional earth Expensive installation.
continuity. Take longer duration to
Can be used in places that are complete the installation.
exposed to water, chemicals, Messy
moisture and heat. Requires additional tools
Can create additional and support
installation with no need to
change the position of the old
installation.

1.2.1

FITMENTS IN
ELECTRICAL
WIRING

3 FITMENT IN
ELECTRICAL

WIRING

Conductors Insulators
Electricity

What is
CONDUCTORS?

Conductors are materials that allow
electricity to flow through them easily


The ability of the material to pass

electricity through it is known as
conductivity
Examples of conductors of electricity
are Copper, Aluminium, Silver, Gold,
Graphite, Platinum, Water, People &
etc

CONDUCTOR Explaination
CHARACTERISTIC

No Characteristic

1 High conductivity to give adequate current carrying capacity and low voltage
drop


2
High strength to maintain ground clearance in long spans

3 Flexibility avoid vibrational fatigue failure

4 Mechanical stability to withstand a variety of loading conditions

5 Physical stability to withstand environmental conditions (e.g. corrosion
resistance)

6 Lifetime stability to maintain the characteristics for 40 50 years

Conductors' use 4. Used as current carriers to
connect different components
1.Used in generator to in circuit
produce electricity 5. Plate / flat / foil / formed
forms of conductors are used
2.Ferromagnetic materials
and alloys like steel are
for capacitors electrodes.
used for transformers , 6. All switchgear, relays,
motors, generators and contractors use conductors to
electromagnet cores make / break and control
current
3.Conductors of relatively 7. Used for heat dissipation /
higher resistivity are used heat transfer.
to make resistors.

What is
INSULATORS?

An insulator is a material that does not
conduct electrical current (low
conductivity).


Insulators are commonly used as a flexible

coating on electric wire and cable.
The main function of this material is to
resist the flow of current as well as heat
through them (resistance)
Example of insulators are paper, plastics,
rubber, Styrofoam, glass & dry air

INSULATORS' FUNCTION & USE

FUNCTION: USES:
Insulator is one kind of Insulators are used in circuits,
material where the internal
electric charge of this does
electric boards to ensure safety
not run freely; insufficient techniques.
electric current will run These insulators protect the
through it in the power of an materials from electricity and heat.
electric field. Electrical wires may be insulated with
rubber, plastics, ceramics and glass.
Larger power cables may used
compressed inorganic powder,
depending on the application.

ELECTRICITY USES:
People use electricity for lighting,
Electricity is the flow of heating, cooling, and refrigeration
electrical power or charge and for operating appliances,
There are two kinds of computers, electronics, machinery,
current electricity: direct
current (DC) and alternating
and public transportation systems
current (AC)
TYPES OF ELECTRICITY PROTECTION
Type of electricity protection wiring
are:
lightning,
earthing /grounding
fuses.

How is Lightning occur?

Lightning happens when the negative
charges (electrons) in the bottom of the
cloud are attracted to the positive charges


(protons) in the ground.

a. Lightning

Lighting causes building fires, burn out

electrical appliances, disrupts telephone

service and radio communication

Lightning protection system includes:

lightning rods,

metal conductor and

ground electrodes

Function of lightning protection is to offer a

low resistance path to ground and to take

any high voltage currents from lightning

strike away from the building

b. earthing /grounding

Electrical Earthing can be defined as
the process of transferring the
immediate discharge of the


electrical energy directly to the

Earth with the help of the low-
resistance wire
Earthing provides a simple path for
the leakage current (eg., the current
that escapes from a device if there’s
any fault in the insulation)

The purpose of earthing /grounding

1 Human Safety
This prevents humans from getting shocked if any internal
faults in the device occur.

2
Safety of Electrical Equipment
It prevents over-current or excessive voltage in
appliances.

Protection of Buildings from Lightning

3 When lightning strikes a building, the copper lightning arrestor draws in the
jolts of lightning and transfers that massive amount of energy to the
ground, thus preventing any damage to the structure or harm to its
occupants.

c. Fuse

A fuse, short for “ fusible link”, is a
type of over current protection.
Essential for safety and will cut off


supply at a certain current level (i.e.

13A, 5A, 3A mains supply fuse)
Fuse has a ‘fusible’ wire element
which heats up when current flows
Excessive current = excessive heat
& wire melts preventing current
flow

Fuse Characteristic

1 Time current characteristic
which shows the time requires to melt the fuse and the time
required to clear the circuit for any given level of overload current

2
Interrupting capacity
which is the maximum current the fuse can safely
interrupt.

3 “fast-blow”/ “time delay”,
according to the time they take to respond to an
overcurrent condition.

How to Select Proper Rating Size of Fuse?

Selecting the proper fuse and its rated size for electrical
appliances is based on different factors and
environments


Basic formula shows how to choose the right size of fuse:
Fuse rating = (power/voltage) x 1.25

e.g: What is the fuse for 10Amp two pin socket?
= (1000w/230v) x 1.25
= 5.4 A
Where, 1kW is the power rating which can be controlled through the
2 pin socket, supply voltage is single phase 230V AC (120V AC)

Types of Fuse

Direct Current Alternating Current
(DC) Fuses (AC) Fuses

CARTRIDGE FUSE

Cartridge fuses are used to protect
electrical appliances such as motors, air-
conditions, refrigerator, pumps etc
There are 2 types of cartridge fuses::


a.General purpose fuse with no time
delay
b.Heavy-duty cartridge fuses with time

delay
Use in 3 pin plug for electrical product
Additional fuse to MCB inside the DB box
Nominal flow 0.15A, 0.25A, 0.5A, 0.75A,
1A, 2A, 3A, 5A, and 13A

REWIREABLE FUSE

Rewireable fuse mostly used in
industries and home electrical
wiring for small current


applications in Low Voltage (LV)

systems.
The wire element fuse made form
alloy
The wire can be change in case of
element breaks
Nominal flow depends of the size of
wire

Think spot

1.List 6 factors to be considered in
selecting the wiring system

2. Name 3 types of wiring system

3. List 3 advantages & disadvantages
of each wiring system

4. Which is TRUE about insulator?

a.An insulator allows electricity to flow
through it easily

b.An insulator is magnetic
c.An insulator is to resist the flow of

current as well as heat through them

1.2.3

STANDARD
SYMBOLS IN
WIRING

BASIC ELECTRICAL WIRING LAYOUT PLAN

STANDARD SYMBOLS FOR ELECTRIC DEVICES

STANDARD SYMBOLS FOR ELECTRIC
SCHEMATIC DRAWING

THANK YOU

DCC50252:
BUILDING
SERVICES

MDM ADILEN @ LUCIA BT SUIL

Lecturer

Dept. of Civil Engineering, POLISAS

1.3 Understand the
safety procedure
SAFETY PROCEDURES based on MS IEC
AND RULES FOR Standard
ELECTRICAL Application of the
safety procedure,
INSTALLATION SYSTEM rules and regulations

1.3.1

UNDERSTAND THE
SAFETY

PROCEDURE
BASED ON MS IEC

STANDARD

MS IEC WHAT IS MS
IEC

STANDARD?

Regulation MS IEC
60364 and Regulation
IEE are the rules that
apply to determine the
uniformity and quality
of installation for
electrical wiring..

Safety Requirements For Electrical Wiring Works
In Residential Buildings

1 Safety 4 First Aid and Basic
Requirements Pulmonary Resuscitation

2 Safety Steps 5 Training Programme

3 Dangers of Electrical 6 Fire Prevention
Shocks

7 Competent Person

1.3.2

APPLICATION OF
THE SAFETY
PROCEDURE, RULES
AND REGULATIONS