Ahmad Fadli Abd Hadi | Petrus Julini Goel | Hasri Hamdan
BASIC ELECTRICAL INSTALLATION All rights reserved. Copyright © Polytechnic Kuching Sarawak 2018 All parts of this book cannot be reproduced in any form or by any means whether electronic, mechanical, photocopying, recording or otherwise, without the written permission of the author. Perpustakaan Negara Malaysia Cataloguing-in-Publication Data Ahmad Fadli Abd Hadi BASIC ELECTRICAL INSTALLATION/ Ahmad Fadli Abd Hadi, Petrus Julini Goel, Hasri Hamdan ISBN 978-967-0797-69-4 1. Electric wiring. 2. Electrical engineering. 3. Government publications--Malaysia. I. PetrusJuliniGoel.II. HasriHamdan. III.Title. 621.31924 FIRST EDITION 2018
NO TOPICS PAGE 1 CHAPTER 1 Electricity Supply System 4 2 CHAPTER 2 Legal Requirements 8 3 CHAPTER 3 Electrical Installation Tools 13 4 CHAPTER 4 Features of Electrical Wiring 17 5 CHAPTER 5 Tariff 42 6 CHAPTER 6 Electrical Wiring Protection 52 7 PRACTICAL 1 Safety And Introduction To Accessories And Tools Used In Electrical Installation 72 8 PRACTICAL 2 PVC Conduit Installation 80 9 PRACTICAL 3 Cable Installation 90 10 PRACTICAL 4 Switch, Socket And Lighting Point Installation 104 11 PRACTICAL 5 Distribution Board Installation 115 12 PRACTICAL 6 Electrical Wiring Test And Commissioning 127
4 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Chapter 1: Electricity Supply System
5 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Recognize the needs of internal distribution Figure 1.1: Structure of the power distribution industry Voltage bands The very nature of the grid system is such that power has to be transmitted over large distances. This immediately creates a problem of voltage drop. To overcome this problem, a high voltage is used for transmission (400 kV or 132 kV), the 400 kV system being known as the ‘Super Grid’. We cannot, however, generate at such high voltages (the maximum in modern generators is 25 kV) and transformers are used to step up the generated voltage to the transmission voltage. At the end of a transmission line is a grid substation, where the requirements of the grid system in that area can be controlled and where the transmission voltage is stepped down via a transformer to
6 | B a s i c E l e c t r i c a l I n s t a l l a t i o n 132 kV. It is at this stage that the different RECs distribute the power required by their consumers around that particular area. The system voltage is then further reduced at substations to 33 000 V,11 000 V and 415/240 V. The declared voltage at consumers’ terminals is now 400 V three phase/ 230 V single-phase + 10% - 6%. However, the measured voltage is still likely to be 415/240 V for many years. Figure 1.2 : Structure of the power distribution range from power generating station to end costumers. Electricity Supply Specifications in Malaysia. Electricity supply for domestic consumers, according to MS IEC 60038 standards, meets the following specifications: - i. Single phase supply with nominal voltage of 230V, range +10%, -6%; ii. Three phase supply with nominal voltage of 400V, range +10%, -6%; iii. Permitted frequency is 50Hz + 1%; iv. Earthing system type (TT System) as in Figure 1.3 and Figure 1.4.
7 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Figure 1.3: TT System (Single Phase) Figure 1.4: TT System (Three Phases) TT System This arrangement covers installations not provided with an earth terminal by the Electricity Supply Company. Thus it is the method employed by most (usually rural) installations fed by an overhead supply. Neutral and earth (protective) conductors must be kept quite separate throughout the installation, with the final earth terminal connected to an earth electrode by means of an earthing conductor. Effective earth connection is sometimes difficult. Because of this, socket outlet circuits must be protected by a residual current device (RCD) with an operating current of 30 mA. Figure 1.3 and 1.4 shows the arrangement of a TT earthing system. All electrical equipment used must be suitable for operation with the stated electricity supply specifications.
8 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Chapter 2: Legal Requirements
9 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Regulation 11(1) of the Electricity Regulations 1994 states that all wiring or rewiring of an installation or extension to an existing installation, which shall be carried out by an Electrical Contractor or a Private Wiring Unit, have to obtain the approval in writing from a licensee or supply authority. Planning of Electrical Wiring Work Prior to carrying out wiring work, the wireman/contractor should plan and determine the tasks to be undertaken so that the work carried out is tidy, neat and safe to be used. The wireman/contractor shall: - i. Undertake a site visit; ii. Determine the consumer load requirements; iii. Calculate the maximum load demand; and iv. Submit the plans, drawings and specifications. Site Visit The purpose of the site visit is to determine: - Electrical equipment suitable for use; Maximum load demand; Single or three phase incoming supply; Type of wiring; and Equipment arrangement. Determining Consumer Load Requirements With the aid of the building floor plans, the installation requirements such as the proposed load, placement of electrical equipment and installation design plans can be determined. Calculating Maximum Load Demand The estimate of the maximum load demand is for determining the specifications of the wiring equipment such as the cables and accessories and subsequently to prepare the electrical installation plans. According to clause 311 of MS IEC 60364 Part 1, to determine the maximum demand for each circuit while ensuring an economic and reliable design within the permitted voltage drop limits. Diversity factors may be taken into account.
10 | B a s i c E l e c t r i c a l I n s t a l l a t i o n The maximum current demand calculations for each circuit must be prepared. These details will show the current requirements, in amperes, for each phase and also assist in determining the cable sizes. Refer to the Third Schedule (Table A and Table B) and Regulation 11(2) of the Electricity Regulations 1994 to estimate the maximum current demand and the diversity factors that may be used for domestic installations. Submission of the Plans, Drawings and Specifications Regulation 65 of the Electricity Regulations 1994 states that the eligibility to submit plans is as follows: - Wireman with Single Phase Restriction – Low voltage single phase up to 60 A. Wireman with Three Phase Restriction – Low voltage up to 60 A. Some related electricity acts used in Malaysia All electrical installation in Malaysia must compliance with a safety requirement which is stated through: Electrical Supply act 1990 ( Act 447 ) Electrical Supply act 1990 ( Amendment ) Act 448 Electrical Regulation 1994 Energy Commission Act 2001 ( Act 601 ) Electrical Supply Act ( Amendment ) 2001 ( Act A 1116 ) Malaysian Wiring Code MS1979:2007 with the adoption of the MS/IEC60364 "Wiring Installation for Building" in 2000, Malaysia, in conformity with other countries in the region are practitioners of a common wiring standard (China and Vietnam in particular are strong proponents of the IEC wiring standard). As the IEC 60364 is drafted by a multi-lateral, international body, which was (and still is, though less so) Eurocentric in nature, the IEC60364 has to accommodate the multiple conditions of various (European) national standards. Due to this the IEC60364 tend, of necessity, to be performance-based in nature. By comparison the U.K. IEE 17th edition or BS7671"Regulations for Electrical Installation", and U.S.A. NEC 2008 "National Electrical Code©" (or NFPA 70) tend to be prescriptive-based as these standards are compiled specifically for only one country.
11 | B a s i c E l e c t r i c a l I n s t a l l a t i o n A quick list of COP (Code of Practice) which are important for designers and installers are as follows: COP05 – All metal enclosures of electrical appliances must be connected to a protective conductor. Water, gas pipes, structural metal parts of the buildings and ducting of air conditioning system must also be connected to the main equipotential bonding. COP07 – Earthing resistance must be less than 10 Ω for operation of RCD but resistance of less than 1Ω is targeted. COP08– Electrical equipment must be mounted within materials that can withstand temperatures produced (by the equipment). COP10 – Water heaters or forced air heaters or steam generators must be equipped with overheating devices. COP16 – Requires determination of short circuit current within the installation. Effectively this requires every TNB district engineer to issue information on short circuit at the point of common coupling (PCC) at the locality of installation. COP19 – Surge Protection Device (SPD) is RECOMMENDED for supply from overhead lines. COP26– Bending radius of 12 times diameter of cable is mandated. This effectively requires that elbows and junctions be used where cable changes direction. COP27– Space factor for conduit shall be 40% and for trunking shall be 45%. COP28– Cables installed behind walls (i.e. embedded in concrete) shall be horizontal or vertical parallel to the edges of the room and within 150mm from top and 150mmfrom edge of wall. COP30 – Wiring within ceiling space (under roof) must be provided with mechanical protection (i.e. installed within APPROVED conduit). In addition they must be installed either parallel or perpendicular to the edges of the wall. COP31– Water heater circuits shall have 2-pole switch installed at suitable location. At the vicinity of the heater a socket outlet is required (unswitch is acceptable).
12 | B a s i c E l e c t r i c a l I n s t a l l a t i o n COP32 – Air Conditioner circuits shall have socket outlet (unswitch type is acceptable) at vanity of unit. COP35– Size of neutral conductor must be same size as phase conductor. COP36– Size of neutral conductor may be reduced (reference to COP35) at the discretion of the Professional Design Engineer (i.e. only a P.Eng can decide). COP39– Minimum cable size shall be 1.5mm² copper or 2.5mm² aluminium. Therefore the practice of using 1.25mm² copper cables is illegal
13 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Chapter 3: Electrical Installation Tools
14 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Electrical installation tools are used to drive a work piece or other tools while doing work. Some examples of electrical installation tools are combination pliers, screwdrivers, Warrington hammer, cable cutters, gimlet and drills. Pliers Pliers are a hand tool used to hold objects firmly, for cutting, bending, or physical compression. Generally, pliers consist of a pair of metal first-class levers joined at a fulcrum positioned closer to one end of the levers, creating short jaws on one side of the fulcrum, and longer handles on the other side. This arrangement creates a mechanical advantage, allowing the force of the hand's grip to be amplified and focused on an object with precision. The jaws can also be used to manipulate objects too small or unwieldy to be manipulated with the fingers. There are many kinds of pliers made for various general and specific purposes such as combination pliers and cable cutters. Figure 3.1: Combination Pliers Screwdriver A screwdriver is used to tighten or loosen screws. There are two common types of screwdriver used, flat screwdriver ( A ) and Philips screwdriver ( B ). The choice of a screwdriver depends on the shape of the screw heads. Figure 3.2: Screwdriver A B
15 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Hammer A hammer head is made of hardened steel specifically on the face and ball parts. The size of a hammer depends on the weight of the head. A hammer is used to hammer a chisel and to hammer a nail. There are many kinds of hammer made for various general and specific purposes such as taper pein hammer which one of the very important tool for wireman. Figure 3.3: Warrington Hammer Gimlet A gimlet is a hand tool for drilling small holes, mainly in wood, without splitting. It was defined in as a piece of steel of a semi-cylindrical form, hollow on one side, having a cross handle at one end and a worm or screw at the other. Figure 3.4: Gimlet Test pen An electrical tester pen , test pen, or voltage detector is a device for quickly checking whether a conductor is live. The device may have the form of a screwdriver. The tip of the device is touched to the conductor being tested (for instance, it can be used on a wire in a switch or inserted into a hole of an electric socket). The type of tester not requiring direct contact is the inductive amplifier.
16 | B a s i c E l e c t r i c a l I n s t a l l a t i o n The user must touch the top of the handle (which is metallic, unlike the rest of the handle), at which point the indicator (LED or neon lamp) will light up, or a speaker will buzz, if the conductor being tested is live. Figure 3.5: Test Pen Drills A drill or drill motor is a tool fitted with a cutting tool attachment or driving tool attachment, usually a drill bit or driver bit, used for drilling holes in various materials or fastening various materials together with the use of fasteners. The attachment is gripped by a chuck at one end of the drill and rotated while pressed against the target material. The tip, and sometimes edges, of the cutting tool does the work of cutting into the target material. This may be slicing off thin shavings (twist drills or auger bits), grinding off small particles (oil drilling), crushing and removing pieces of the work piece (SDS masonry drill), countersinking, counter boring, or other operations. Figure 3.6: Drill
17 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Chapter 4: Features of Electrical Wiring
18 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Electrical wiring composes of electrical equipment such as cables, switch boards, main switches, miniature circuit breakers (MCB) or fuses, residual current devices (RCD), lighting points, power points, lightning arrestors, etc. Example of a single phase consumer electrical wiring is as shown in Figure 4.1. Figure 4.1: Single Phase Consumer Electrical Wiring TYPES OF WIRING Electrical wiring in general refers to insulated conductors used to carry electricity, and associated devices. This section describes general aspects of electrical wiring as used to provide power in buildings and structures, commonly referred to as building wiring.
19 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Surface wiring Surface wiring is a system where all of the components (e.g. Cable, PVC, GI ‘Galvanized Iron’ conduit) are mounted to the surface of the wall or ceiling so we don’t have to cut holes and fish wires through walls. Figure 4.2: Surface Wiring Conceal wiring Conceal wiring is a system where all of the components (e.g. Cable, PVC, GI ‘Galvanized Iron’ conduit) are mounted inside the wall. The cable end will surface from wall through conceal boxes. Each cable be terminate and spare on the wall surface for electrical wiring accessories connection. Figure 4.3: Conceal Wiring Selection of Wiring Cable Type The selection of the cable size has to take into consideration the following:- All wiring cables must be PVC or PVC/PVC insulated with copper conductors. Conductors with cross sectional areas of 16mm2 or less must be of copper. Aluminium conductors are not permitted.
20 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Cables for swimming pools must be water resistant PE (polyethylene) insulated; The selected cable must be capable of delivering the electrical energy efficiently; The cable size allows it to carry the current without heating the cable; The cable insulation must be suitable for the surrounding conditions of the installation, such as the ability to withstand the surrounding temperatures and the ability to provide mechanical protection; Each conductor in the installation must be protected from overcurrent by means of over-current protection devices needed to prevent damage to the cable insulation. Factors Related to Cable Current Carrying Capacity The following factors in relation to the current carrying capacity of cables must be taken into consideration:- i. Surface wiring using clips – group factor; ii. Wiring using conduits – space factor 40%; iii. Wiring using ducts – space factor 45%; iv. Concealed wiring – group factor; and v. Concealed wiring using ducts – surrounding temperature factor. Use of Minimum Cross Sectional Area Rating of Wiring Conductors Table 4.1 show the minimum cross sectional areas of conductors based on their applications:- Table 4.1: Minimum Cross Sectional Area Conductor Cross Sectional Area in mm2 Material Application 1.5 mm2 Copper Lighting/fan circuit 2.5 mm2 Copper 13A socket outlet circuit 4.0 mm2 - 6.0 mm2 Copper General Power Circuit (example: water heater, cooker unit, motor/pump) 16.0 mm2 / 25.0 mm2 Copper Main Circuit
21 | B a s i c E l e c t r i c a l I n s t a l l a t i o n FUNCTIONS AND COLOUR IDENTIFICATION OF NON FLEXIBLE CABLES Table 4.2 shows the functions and colour identification of non-flexible cables: Table 4.2: Function and colour identification Function Cable Colour Phase of Single Phase Circuit Red, Yellow or Blue Red Phase of Three Phase Circuit Red Yellow Phase of Three Phase Circuit Yellow Blue Phase of Three Phase Circuit Blue Neutral of Circuit Black Protection/Earthing Conductor Green or Green-Yellow Flexible Cables Figure 4.4: Flexible cable Flexible cables of cross sectional area less than 4.0 mm2 are used in installations for electrical accessories such as ceiling roses, lamp fixtures or attachments, socket plugs for mobile appliances, etc. Flexible cables shall not be used for permanent wiring. Flexible cables for the permanent use of electrical appliances should not exceed 3 meters in length.
22 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Table 4.3: Flexible cable No. of Cores Function Cable Colour 1, 2 or 3 Phase Conductor Brown Neutral Conductor Blue Protection Conductor Green or GreenYellow 4 or 5 Phase Conductor Brown or Black Neutral Conductor Blue Protection Conductor Green or GreenYellow CONDUCTOR INSULATION AND TYPES OF WIRING Various material and insulation layers are used for conductor protection. Cable selection in accordance to insulation layers must be done correctly for the type of the wiring installation as shown in the table 3.10 below: Table 4.4: Conductor Insulation vs Types of Wiring Conductor Insulation Layer Wiring Type Single Insulated Conductor Conduit, Duct or Concealed Double Insulated Conductor Surface Armored PVC Insulated Conductor Underground Cable Insulator Figure 4.5: Example of insulator
23 | B a s i c E l e c t r i c a l I n s t a l l a t i o n An electrical insulator is a material whose internal electric charges do not flow freely, and therefore does not conduct an electric current under the influence of an electric field. A perfect insulator does not exist, but some materials such as glass, paper and Teflon, which have high resistivity, are very good electrical insulators. A much larger class of materials, even though they may have lower bulk resistivity, are still good enough to insulate electrical wiring and cables. Examples include rubber-like polymers and most plastics. Such materials can serve as practical and safe insulators for low to moderate voltages (hundreds, or even thousands, of volts). Insulators are used in electrical equipment to support and separate electrical conductors without allowing current through themselves. An insulating material used in bulk to wrap electrical cables or other equipment is called insulation. The term insulator is also used more specifically to refer to insulating supports used to attach electric power distribution or transmission lines to utility poles and transmission towers. Insulators are commonly used as a flexible coating on electric wire and cable. Since air is an insulator, in principle no other substance is needed to keep power where it should be. High-voltage power lines commonly use just air, since a solid (e.g., plastic) coating is impractical. However, wires that touch each other produce cross connections, short circuits, and fire hazards. In coaxial cable the center conductor must be supported exactly in the middle of the hollow shield in order to prevent EM wave reflections. Finally, wires that expose voltages higher than 60V can cause human shock and electrocution hazards. Insulating coatings help to prevent all of these problems. Rubber For many years wiring cables were insulated with vulcanized natural rubber (VIR). Much cable of this type is still in service, although it is many years since it was last manufactured. Since the insulation is organic, it is subject to the normal ageing process, becoming hard and brittle. In this condition it will continue to give satisfactory service unless it is disturbed, when the rubber cracks and loses its insulating properties. It is advisable that wiring of this type which is still in service should be replaced by a more modern cable. Synthetic rubber compounds are used widely for insulation and sheathing of cables for flexible and for heavy duty applications. Many variations are possible, with conductor temperature ratings from 60°C to 180°C, as
24 | B a s i c E l e c t r i c a l I n s t a l l a t i o n well as resistance to oil, ozone and ultra-violet radiation depending on the formulation. Paper Dry paper is an excellent insulator but loses its insulating properties if it becomes wet. Dry paper is hygroscopic, that is, it absorbs moisture from the air. It must be sealed to ensure that there is no contact with the air. Because of this, paper insulated cables are sheathed with impervious materials, lead being the most common. PILC (paper insulated lead covered) is traditionally used for heavy power work. The paper insulation is impregnated with oil or non-draining compound to improve its long-term performance. Cables of this kind need special jointing methods to ensure that the insulation remains sealed. This difficulty, as well as the weight of the cable, has led to the widespread use of p.v.c. and XLPE (thermosetting) insulated cables in place of paper insulated types. P.V.C. Polyvinyl chloride (p.v.c.) is now the most usual low voltage cable insulation. It is clean to handle and is reasonably resistant to oils and other chemicals. When p.v.c. burns, it emits dense smoke and corrosive hydrogen chloride gas. The physical characteristics of the material change with temperature: when cold it becomes hard and difficult to strip, and so BS 7671 specifies that it should not be worked at temperatures below 5°C. However a special p.v.c. is available which remains flexible at temperatures down to -20°C. At high temperatures the material becomes soft so that conductors which are pressing on the insulation (eg at bends) will 'migrate' through it, sometimes moving to the edge of the insulation. Because of this property the temperature of general purpose P.V.C. must not be allowed to exceed 70°C, although versions which will operate safely at temperatures up to 85°C are also available. If p.v.c. is exposed to sunlight it may be degraded by ultra-violet radiation. If it is in contact with absorbent materials, the plasticiser may be 'leached out' making the p.v.c. hard and brittle.
25 | B a s i c E l e c t r i c a l I n s t a l l a t i o n DIVERSITY FACTOR The size of a cable or accessory is not necessarily determined by the total power rating of all the current-consuming devices connected to it. It depends on what percentage of the connected load is likely to be operating at any one time. This percentage use is called the Diversity Factor. Table 4.5 gives an indication of the diversity factors that may be applied to parts of an installation, but it must be remembered that the figures given are only a guide. The amount by which the figures given are increased or decreased for any given installation should be decided by the engineer responsible for the design. The values given in the table refer to percentages of connected load. In calculating the maximum current, appliances and socket outlets should be considered in order of their current ratings, the largest first.It should be noted that the object of applying diversity to domestic final circuits is not to enable a reduction in cable size, but to arrive at a reduced current demand for the whole installation. This will mean that the size of the main tails, consumer unit and any control gear, etc., can be reduced. Table 4.5: Allowances for diversity Circuit Percentage diversity Lighting 66% Cooking appliances the first 10 A of the cooker load + 30% of the remainder + 5 A if the cooker unit has a socket outlet Instantaneous water heaters 100% of full load of the first and second (Showers, etc.) largest appliances + 25% of full load of remaining appliances Water heaters thermostatically controlled (immersion heaters) no diversity allowed Ring and radial circuits to BS1363 100% of full load of largest circuit + 40% of full load of all other circuits
26 | B a s i c E l e c t r i c a l I n s t a l l a t i o n DEFINE THE FINAL CIRCUIT Final circuits refers to circuits distributed from the Distribution Board (DB) to serve the costumer electrical appliances power demand. Final circuit protection and control unit is separated from the outside power generation distribution so to provide more convenient maintenance process and future wiring failure. Unless domestic premises are extremely large, it is unlikely that a three-phase supply would be needed, and consequently only single-phase systems will be considered here. Figures 1.3 illustrate the typical intake arrangements for TT systems. Although many TT installations are protected by one single 30 mA residual current device (RCD) (as shown in Figure 4.6), this does not conform to the IEE Regulations regarding ‘installation circuit arrangement’. The requirement is that circuits which need to be separately controlled, e.g. lighting and power, remain energized in the event of the failure of any other circuit of the installation. Hence, an earth fault on, say, a socket-outlet circuit would cause the whole of the installation to be cut off if protected by one 30 mA RCD. Figure 4.6: TT earthing connection for single phase consumer unit. 240V 50Hz kWH Distribution Board (DB)
27 | B a s i c E l e c t r i c a l I n s t a l l a t i o n ASSEMBLE TYPES OF FINAL CIRCUITS Lighting Circuits Lighting circuit is associated with various types of luminaries such as fluorescent lamp, filament lamp, decorative (neon) lamp which is controlled by various types of switches and current limiting devices called Miniature Circuit Breakers (MCB). The current rating for the lighting final circuit is normally 6 ampere and the size of pvc cable used is 1.5mm². The maximum number of lighting points allowed to be connected to this circuit is 10 lamp points (including ceiling fan). There are three basic types of switches normally used in this type of circuit, namely one way switch, two way switch and intermediate switch. Each of these switches has different purposes and applications Figure 4.7: Single light point controlled by a one way switch.
28 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Figure 4.8: Two light points controlled separately by two one way switches Figure 4.9: Single light point controlled by a two way switch
29 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Figure 4.10: Three light points controlled by two way switches and intermediate switch Figure 4.11: Single fluorescent light point controlled by a one way switch
30 | B a s i c E l e c t r i c a l I n s t a l l a t i o n POWER CIRCUITS Domestic circuits are both radial or ring final circuits and are likely to be arranged in the following ways. Radial circuits are fed from the consumer unit and run in either a chain or like the spokes of a wheel, i.e. they radiate out from their source. Typical of domestic radial circuits are lighting, water heating, and storage heating and cooking. Figure 4.12: Radial circuit connection to 3 units socket outlet. Ring final circuits are almost unique to the UK. The ring final circuit is always used to feed 13 A socket outlets to BS 1363. The circuit starts at the consumer unit, loops in and out of each socket and, finally, returns to the consumer unit to terminate in the same terminals as it started. Figure 4.13: Ring circuit connection to 5 units socket outlet. E N L L N MCB 16A P 1 E N L E N L P 2 P 3 E E N L L N MCB 32A P 1 E N L E N L P 2 P 3 E E N L E N L P 4 P 5
31 | B a s i c E l e c t r i c a l I n s t a l l a t i o n APPROXIMATION OF CURRENT DEMANDS Maximum Current Demand Maximum current demand is considered as one time, highest total of current flowing through the costumer final circuit. The maximum current demand for final circuit can be determine from the summation of overall current demand from each load or electrical appliances connected to the circuit. Table 4.6 below show the order to determine overall current demand in final circuits. Table 4.6: Load base and electrical appliances current demand approximation. Load Base and electrical appliances Current Demand Approximation 15 Amp socket outlet 13 Amp socket outlet 5 Amp socket outlet 2 Amp socket outlet 15 Amp 13 Amp 5 Amp not less than 0.5 Amp Light point (Other than discharge light) Equal to load current. 100 Watt each lamp holder. Electric Clock, Electric saver and appliances less than 15 volt-ampere (Volt -Ampere = Apparent power) Ignore Other static appliances. Equal to load current approximation or normal current.
32 | B a s i c E l e c t r i c a l I n s t a l l a t i o n DETERMINE THE MAXIMUM REQUIREMENTS AND ALLOWANCES Final Circuit for 13A Socket Outlets The total number of final circuits needed, the size of the conductors used and the maximum permitted floor area to be served can be determined by being guided by the table below. Table 4.7: Power circuits final protection, cable and covered area. Circuit Type Over Current Protection Rating (Fuse or MCB) (Ampere) Minimum Size of Copper Conductor in PVC or Rubber Insulation (mm2) Maximum Floor Area (m2) Ring 30 or 32 2.5 100 Radial 30 or 32 4.0 50 Radial 20 2.5 20
33 | B a s i c E l e c t r i c a l I n s t a l l a t i o n TESTING Legal Requirements i. Sub regulation 12(1) and 12(2) of the Electricity Regulations 1994 state that any electrical wiring in an installation shall be under the immediate supervision of a Wireman with Single Phase Restriction or Three Phase Restriction. Upon completion, the Wireman shall certify a Supervision and Completion Certificate. ii. Sub regulation 13(1) and 13 (2) of the Electricity Regulations 1994 state that the installation shall be tested by a Wireman with Single Phase Restriction or a Wireman with Three Phase Restriction authorised to test any installation, and who shall certify a Test Certificate for the installation. On completion of a wiring installation, a number of tests on the installation have to be conducted to ascertain that the wiring circuits and connected appliances are safe for use. Prior to carrying out the tests, an inspection has to be done. The following tests shall be conducted: i. Continuity Test; ii. Insulation Resistance Test; iii. Polarity Test; iv. Earth Electrode Resistance test; and v. Residual Current Device Test. A. CONTINUITY TEST There are 3 main types of continuity tests for the final circuits:- i. Protection Conductor Continuity Test. ii. Final Ring Circuit Conductor Continuity Test. iii. Live and Neutral Conductor Continuity Test. 1. Protection Conductor Continuity Test To ascertain that all protection conductors are connected in the correct and effective manner. Test equipment – Multimeter (Ohm range) or Ohm meter. Test Method:
34 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Ensure that the main switch, RCD and MCB are open circuited (switched off) and all loads are disconnected; Connected the test leads as in the Figure 4.14; The meter reading shall be less than 1 ohm. Figure 4.14: Protection Conductor Continuity Test 2. Final Ring Circuit Conductor Continuity Test To ensure that all conductors around the ring circuit have continuity; Test Equipment – Multimeter (Ohm range) or Ohm Meter Test Method: Disconnect both the supply source live conductors from the MCB, the neutral conductor from the neutral terminals and the earth conductor from the earth terminal in the distribution fuse box; Connect the test leads as in the Figure 4.15 (EE); Repeat the procedure for (L-L) and (N-N); The meter reading value shall be less than 1 ohm. E
35 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Figure 4.15: Final Ring Circuit Conductor Continuity Test 3. Live And Neutral Conductor Continuity Test To ensure that each conductor in the circuit has continuity; Test Equipment – Multimeter (Ohm range) or Ohm Meter Test Method: Switch off the Main switch, RCD and MCB; Disconnect all loads; Switch on all switches in the circuit; Disconnect the fuses/final circuit breakers and close the circuit; Carry out the test as shown in Figure 4.16; The meter reading value shall be less than 1 ohm.
36 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Figure 4.16: Live and Neutral Conductor Continuity Test B. INSULATION RESISTANCE TEST i. Ensure that there is no leakage current between phase conductors, phase and neutral conductors and phase conductor and earth. ii. Test the strength of the cable insulation. iii. Test Equipment – Insulation Resistance Tester.operating voltage is 250VDC or 500VDC. iv. Test Method: Switch off main switch; Disconnect all loads; Switch on all circuit control switches; Carry out test as in the Table below; Meter reading value shall be less than 1 Megaohm.
37 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Test At Single Phase Consumer Unit Test At Final Lighting Circuit Test At 13A Socket Outlet Circuit – Radial Circuit and Ring Circuit L & N L & N L & N L & E L & E L & E N & E N & E N & E Minimum values for insulation resistance are as in the table below. Nominal Circuit Voltage (Volts) A.C. Test Voltage (Volts) Minimum Insulation Resistance (Mega Ohms) Extremely low voltage circuit receiving supply from an isolating transformer / SELV 250 0.25 Figure 4.17: Insulation Resistance Test
38 | B a s i c E l e c t r i c a l I n s t a l l a t i o n C. POLARITY TEST i. Ensure that each fuse or single pole control and protection device is connected only in the phase conductor. ii. Intermediate contact of Edison screw lamp holder is connected to the phase conductor. iii. Ensure that phase, neutral and earth conductors at socket outlets are connected at the correct terminals. iv. Test Equipment – Multimeter (Ohm range) or Ohm meter or Socket Tester. v. Test Method: Switch off Main switch; Disconnect all loads Switch on all circuit control switches; Carry out test as in Figure 4.18; Test switches and single phase control devices at the phase conductors. Test socket outlet connection sources. Test Edison screw lamp holder connections. Meter reading value shall be less than 1 ohm. Figure 4.18: Polarity test
39 | B a s i c E l e c t r i c a l I n s t a l l a t i o n D. EARTH ELECTRODE RESISTANCE TEST i. To test the earth electrode resistance. ii. To ascertain the suitability of the location of the electrode. iii. To ensure that the electrode is not buried within the resistance area of another electrode. iv. Test equipment – Earth Resistance Tester. v. Test method: - Terminal ’E’ is connected to the electrode to be tested (green conductor) Terminal ‘P’ is connected to the potential spike (yellow conductor) at a distance of 10 meters from the earth electrode. Terminal ‘C’ is connected to the current spike (red conductor) at a distance of 20 meters from the earth electrode. Figure 4.19: Earth Electrode Resistance Measurement Earth Electrode Resistance Measurement Method (Figure 4.20) This test must be repeated at least three times, to ensure that the reading is not affected by interacting earthing regions. i. Record the first reading (Z1). Example : Z1 = 10 Ω ii. Move the voltage spike to a distance of 6 meters from the original position. Record the second reading (Z2). Example : Z2 = 10 Ω iii. Move the voltage spike to a distance of 6 meters from the original position. Record the third reading (Z3). Example : Z3 = 10 Ω
40 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Figure 4.20: Earth Electrode Resistance Measurement Result: From the three resistance values, obtain the average value of the tested earth electrode resistance. E. RESIDUAL CURRENT DEVICE TEST i. Ensure that the residual current device (RCD) trips within the set time on the occurrence of current leakage to earth. ii. Test Equipment – RCD Tester/ RCCB Tester/ Socket Tester iii. Test Method 1 Use the Trip Test Button Press the trip button found on the RCD to determine if it trips or otherwise. This test would not be able to determine the sensitivity of the RCD nor the time taken for it to trip. iv. Test Method 2 Use a socket tester This equipment is as shown in Figure 4.21 can be connected to a 13A socket outlet. It have 3 indicators that usually indicate polarity termination and
41 | B a s i c E l e c t r i c a l I n s t a l l a t i o n equipped with a RCD test button. Press the test button on the Socket tester to trip the RCD. Figure 4.21: ELCB/RCD/RCCB and Socket Tester v. Test Method 3 Use a RCD Tester This equipment is equipped with a 13A plug which can be connected to a 13A socket outlet. Select the RCD sensitivity to be the same as the sensitivity of the RCD to be tested, to determine if the RCD can trip. The time to trip shall not exceed 40 millisecond. 13A Socket condition neon light indicator Neon light on/off definition ELCB/RCD/RCCB test button (below 100mA)
42 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Chapter 5: Tariff
43 | B a s i c E l e c t r i c a l I n s t a l l a t i o n UNDERSTAND TARIFFS Power Generation Company usually used electricity tariff as a payment scale to charge the costumers. Tariff is charges that impose to the total of electricity supply used by the costumer. There are 3 type of Electrical Energy Supply normally used in Malaysian stated below: i. Domestic Supply Means supply of energy to premises used only for private dwelling purposes, provided that no commercial activity is carried out in such premises. ii. Commercial Supply Means the supply of energy from the Company's supply lines to all commercial premises including office block, shop, restaurant, school, hotel, boarding house, farms, estate, port, broadcasting and telecommunication installation, cinemas and entertainment locations, military and Government installations and hospital, and any supply used in the construction or building activities, but excluding private dwellings and industrial premises. iii. Industrial Supply Means supply of energy to industrial operation such as manufacturing, quarrying, mining, shipbuilding business, and to consumers who utilize energy for the purpose of pumping water, in whose premises electric motors and plants are used in connection therewith and the total wattage of lamps and air-conditionings installed for purpose of office use shall not exceed twenty per cent (20%) of the total wattage of all electric equipment installed.
44 | B a s i c E l e c t r i c a l I n s t a l l a t i o n BILLING DEMAND Measured in kW means the maximum demand registered during the month or seventy-five per cent (75%) of the maximum demand registered during the preceding eleven (11) months or the contract demand, whichever is higher; contract demand being equal to the estimated demand at the meter point at the time of connection. Maximum Demand Means measured in kW, twice the largest number of kilowatt-hours supplied during any consecutive thirty minutes in any month. Several Term Related To Electricity Tariff (ref. SESCO) Table 5.1: Additional definitions impose related to electrical tariff. No. Term Definitions 1 AVERAGE POWER FACTOR Means the cosine of the angle of which the tangent is obtained by dividing the total of the reactive kilovolt-amperehours by the total of the kilowatt-hours recorded in any month by the company's meters. 2 MONTH Means the period between two successive meter readings, meters are normally read at intervals of approximately thirty days. 3 OFF-PEAK PERIOD Means the period between 0000 hours and 0700 hours. 4 PEAK PERIOD Means the period between 0700 hours and 2400 hours. 5 PUBLIC LIGHTING SUPPLY Means supply of energy to any legal entity in respect of street lightings and other general lighting purposes. 6 SCHOOL Includes kindergarten, children play school, nursery, tuition centers, college and universities and any institutions offering study courses of any nature.
45 | B a s i c E l e c t r i c a l I n s t a l l a t i o n SCHEDULE OF TARIFF Tariff rate listed in Table 5.2 below were charged by SESCO in SARAWAK region started April 1st 2007. Table 5.2: Electricity tariff rate in Sarawak region since April 2007. TARIFF TYPE TARIFF DEFINITION TARIFF CALCULATION 1. TARIFF C1 - COMMERCIAL RATE PER UNIT For the first 100 units per month 40 sen For the next 4900 units per month 34 sen For each additional unit per month 30 sen Minimum monthly charge RM 10.00 2. TARIFF C2 - COMMERCIAL DEMAND RATE PER UNIT For each kilowatt of maximum demand per month RM 16.00 For each unit 25 sen Minimum monthly charge RM 16.00 per kilowatt X Billing Demand 3. TARIFF C3 - COMMERCIAL PEAK/OFF-PEAK DEMAND RATE PER UNIT For each kilowatt of maximum demand per month during the peak period RM 20.00 For each unit during the peak period 25 sen For each unit during the off-peak period 14.4 sen Minimum monthly charge RM 20.00 per kilowatt X Billing Demand 4. TARIFF D -DOMESTIC RATE PER UNIT For the first 100 units per month 34 sen For the next 300 units per month 29 sen For each additional unit per month 33 sen Minimum monthly charge RM 5.00 5. TARIFF I1 - INDUSTRIAL RATE PER UNIT For the first 100 units per month 40 sen
46 | B a s i c E l e c t r i c a l I n s t a l l a t i o n For the next 2900 units per month 30 sen For each additional unit per month 27 sen Minimum monthly charge RM 10.00 6. TARIFF I2 - INDUSTRIAL DEMAND RATE PER UNIT For each kilowatt of maximum demand per month RM 16.00 For each unit 22.2 sen Minimum monthly charge RM 16.00 per kilowatt X Billing Demand 7. TARIFF I3 - INDUSTRIAL PEAK/OFFPEAK DEMAND RATE PER UNIT For each kilowatt of maximum demand per month during the peak period RM 20.00 For each unit during the peak period 23.4 sen For each unit during the off peak period 14.4 sen Minimum monthly charge RM 20.00 per kilowatt X Billing Demand 8. TARIFF PL - PUBLIC & STREET LIGHTING RATE PER UNIT For each unit 47 sen Minimum monthly charge RM 10.00
47 | B a s i c E l e c t r i c a l I n s t a l l a t i o n HOW TO FIGURE ELECTRICITY TARIFF Example 1 ( Domestic – Tariff D) Step 1: Meter reading before : 1005 Kwh Step 2: Meter reading after : 1235Kwh Step 3: Unit consumed : 1235 – 1005 = 230 Kwh Step 4: Refer to Tariff D in Table 5.2, calculation showed in figure 5.1 below state that the consumed amount for the specified month/period is RM71.70 Figure 5.1: Domestic Tariff calculation for units consumed less than 400 Kwh. Example 2 ( Domestic – Tariff D) Step 1: Meter reading before: 1005 Kwh Step 2: Meter reading after: 2000Kwh Step 3: Unit consumed: 2000 – 1005 = 995 Kwh Step 4: Refer to Tariff D in Table 5.2, calculation showed in Figure 5.2 below state that the consumed amount for the specified month/period is RM317.35
48 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Figure 5.2: Domestic Tariff calculation for units consumed more than 400 Kwh. Example 3 ( Commercial – Tariff C1) Step 1: Meter reading before: 1005 Kwh Step 2: Meter reading after: 2000Kwh Step 3: Unit consumed: 2000 – 1005 = 995 Kwh Step 4: Refer to Tariff C1 in Table 5.2 , calculation showed in Figure 5.3 below state that the consumed amount for the specified month/period is RM344.30 Figure 5.3: Commercial Tariff calculation for units consumed less than 995 Kwh.
49 | B a s i c E l e c t r i c a l I n s t a l l a t i o n SEPARATE ELECTRICITY TARIFF How to figure appliance costs? Costumer can calculate the electricity tariff for each appliances used in their home. Separate electricity tariff is reasonable for costumer in order to determine the cost raise by each one of the appliance used in their home, shop or factory to practice power consumption reduction. Each electrical appliance usually comes with stated power rating and some of it listed in Table 5.3 below. The list provided may not include all of the electrical appliances we use. If our appliance is not listed in the chart or if the wattage is different, we can determine the approximate operating cost if we know three things: Wattage of the appliance (usually found in a metal plate or etched into the appliance). Number of hours you use your appliance. Amount you pay per kilowatt-hour for electricity. The cost figures used in this book are based on average cost of $0.29 per kilowatt hours (kwh) of electricity When we have these three numbers, use the following formula to find the cost of using our appliance. wattage of appliance x hours of operation 1000 x electric rate = operation cost. For example: A 130 watts TV set is used for 5 hours daily. Therefore the cost of using the TV set daily would be; 130 x 5 1000 x RM 0.29 (on average cost) = RM 0.19 cent
50 | B a s i c E l e c t r i c a l I n s t a l l a t i o n Assuming that the usage is constant, the cost for using TV set for a month (assume 30 days) would be RM0.19 cent x 30 days = RM5.70 Table 5.3: Home electrical appliances and power consumption. Home Entertainment Appliance Wattage Cost (RM/Months) Computer 250 6.53 Hi-Fi set - RMS O/P 25w + 25w 170 4.44 - RMS O/P 40w + 40w 250 6.53 - RMS O/P 65w + 65w 450 11.75 Television Coloured -14" 70 2.44 -16" 90 3.13 - 20" 130 4.52 - 26" 180 6.26 Television Black & White - 14" 50 1.74 - 20" 60 2.09 - 24" 70 2.44 Video Cassette Recorder 85 2.96 Miscellaneous Clock 2 0.01 Electric Drill 250 0.87 Floor Polisher 300 0.58 Vacuum Cleaner 1000 0.87 Lightings (average usage 5 hrs/day) - Flourescent 20 1.39 ... 32 1.74 ... 40 3.48 ... 80 0.22 - Filament 5 0.65 ... 15 1.09 ... 25 1.74 ... 40 2.61 ... 60 3.26 ... 75 4.35