cp 88 code of practice for temporary electrical installations

Publishedby

CP 88 : Part 1 : 2001 (ICS 29.260.10)

SINGAPORE STANDARD

Code of practice for temporary electrical installations Part 1 : Construction and building sites Incorporating Erratum No. 1 Amendment No. 1 (issued separately)

Licensed by SPRING Singapore to WEI JIAN/MR, CHH CONSTRUCTION SYSTEM PTE LTDSingapore Standards eShop Order No: 6800031056/Downloaded:2015-04-07Single user licence only, copying and networking prohibited

CP 88 : Part 1 : 2001 (ICS 29.260.10)

SINGAPORE STANDARD

Code of practice for temporary electrical installations Part 1 : Construction and building sites

All rights reserved. Unless otherwise specified, no part of this Singapore Standard may be reproduced or utilised in any form or by any means, electronic or mechanical, including photocopying and microfilming, without permission in writing from SPRING Singapore at the address below: Standards SPRING Singapore 1 Fusionopolis Walk, #01-02 South Tower, Solaris Singapore 138628 Email : [email protected]

ISBN 9971-67-837-3


CP 88 : Part 1 : 2001

2

This Singapore Standard having been approved by the Electrical Industry Practice Committee wasendorsed by the Standards Council on 22 February 2001.

First published, 2001

The Electrical Industry Practice Committee appointed by the Standards Council consists of thefollowing members:

Name Organisation

Chairman : Mr Soh Siew Cheong Standards Council

Secretary : Mr Dennis Chew Singapore Productivity and Standards Board

Members : Assoc Prof Chang Che Sau National University of SingaporeMr Foo Kong Deen Singapore Electrical Trade AssociationMr Goh Eng Kee Ngee Ann PolytechnicMr Ho Fui Chan Housing & Development BoardMr Ho Sou Weng Singapore PolytechnicEr. N P Karthigayan Institution of Engineers Singapore

Mr Bernard Koh Institute of Technical EducationMr Leong Kok Yeong Association of Consulting Engineers, SingaporeMr Samuel Ong Bor Hwee Singapore Electrical Contractor AssociationMr Pang Toh Kang PWD Corporation Pte LtdMr Tan Sing Ong Jurong Town CorporationAssoc Prof Teo Cheng Yu Nanyang Technological UniversityMr Wan Fook Sing Singapore Contractor Association LimitedMr Wu Ching Chan Temasek PolytechnicMr Yeo Yek Seng Public Utilities Board

The Technical Committee on Temporary Electrical Installations appointed by the Electrical IndustryPractice Committee and responsible for the preparation of this Part of the Code consists ofrepresentatives from the following organisations:

Name Organisation

Chairman : Mr Tan Hak Khoon Public Utilities Board

Secretary : Ms Jessie Chow Singapore Productivity and Standards Board

Members : Mr Foo Meng Wah Ministry of ManpowerMr Jimmy Ho Real Estate Developers Association of

SingaporeMr Simon Lee Singapore Contractors Association LtdMr Lim Ah Hee Housing & Development BoardEr. Lum Chong Chuen Institution of Engineers SingaporeMr Ng Kim Leong PWD Corporation Pte Ltd

served until 2 June 2000


CP 88 : Part 1 : 2001

3

Members : Mr Ng Kin Ming Singapore Electrical Contractors AssociationMr Pang Boon Kiat Power Supply LtdMr T Gopala Krishna Rao Singapore Institution of Safety OfficersMr Rozario Robert Association of Singapore Marine IndustriesEr. Ken Tan See Pian Association of Consulting Engineers, SingaporeMr Toh Teck Boon Singapore Electrical Trades AssociationMr Yee Cheong In Singapore Productivity and Standards BoardMr Yong Siew Hwa Building and Construction Authority As amended

May 2001


CP 88 : Part 1 : 2001

4

(blank page)


CP 88 : Part 1 : 2001

5

ContentsPage

Foreword 8

CODE OF PRACTICE

1 General 9

1.1 Scope 9

1.2 Object 9

1.3 Relationship with statutory regulations 9

1.4 Use of established materials, equipment and methods 10

1.5 New materials and inventions 10

2 Definitions 10

3 General requirements 11

3.1 Source of supply 11

3.1.1 General 11

3.1.2 Types of supply 11

3.1.3 No parallel operation of generating set and the public electricity supply system 12

3.1.4 Supply for equipment 12

3.2 Type of earthing arrangement 12

3.3 Installation of generating set 13

3.3.1 General 13

3.3.2 Earthing arrangements of generating set 13

3.3.3 Protection against direct contact of live parts 13

3.3.4 Labelling on generating set 13

4 Protection for safety 14

4.1 Control of supply 14

4.1.1 General 14

4.1.2 Protective device for incoming supply 14

4.1.3 Protection of circuits 14

4.1.4 Prohibited use of fuses for final circuits 14

4.2 Protection against direct contact 15

4.3 Protection against indirect contact for low voltage system 15

4.3.1 General 15

4.3.2 Protection by residual current device 15

4.3.3 Protection by residual current device for final circuits 15

4.3.4 Earth leakage protection for transportable electrical equipment 16

4.3.5 Protective conductor proving and earth monitoring systems 16

4.4 Protection against indirect contact for reduced voltage system 16


CP 88 : Part 1 : 2001

6

Page

4.5 Protection against lightning 16

5 Selection and erection of equipment 17

5.1 General 17

5.2 Wiring systems 17

5.3 Switchgear and controlgear 19

5.3.1 Enclosure for low-voltage assembly 19

5.3.2 Switchboard and distribution board 19

5.4 Socket-outlets assembly 19

5.5 Plugs, socket-outlets and cable couplers 23

5.6 Cable for SOA connection 23

5.7 Earthing arrangement and protective conductor 24

5.7.1 Protective earthing of metalwork 24

5.7.2 Earthing of portable appliances and tools 24

5.7.3 Earthing of metal sheath and armour of cables 24

5.7.4 Metal sheath and/or armour of flexible or trailing cables 24

5.7.5 Earthing of metal enclosure for switchboards and distribution boards 24

5.8 Other equipment 24

5.8.1 Light fixtures 24

5.8.2 Portable hand-lamps 24

5.8.3 Prohibited use of lampholders fitted with pin contacts 24

5.8.4 Electrical welding system 25

5.9 Equipment for reduced voltage system 25

5.9.1 Plug, socket-outlet and cable coupler of a reduced voltage system 25

5.9.2 Switches for reduced voltage circuits 25

6 Inspection, testing and maintenance 25

ANNEXES

A Statutory regulations and associated memoranda 26

B Protective conductor proving and earth monitoring systems 27

C Temporary electrical installations inspection checklist forconstruction and building sites 31

D Danger signboard 36

E Clauses that are extracted from British Standards 37


CP 88 : Part 1 : 2001

7

Page

TABLES

1 Maximum earth fault loop impedance (Zs) for a disconnection time5s and Uo of 55V (single-phase) 16

2 Colour coding 23

FIGURES

1 Single-phase socket-outlet assembly fed from single-phase source 21

2 Single-phase socket-outlet assembly fed from three-phase source 21

3 Three-phase socket-outlet assembly 22

4 Three-phase and single-phase socket-outlet assembly 22

B1 Basic circuit for protective conductor proving unit 29

B2 Basic circuit for earth monitoring unit 30


CP 88 : Part 1 : 2001

8

Foreword

This Part of the Singapore Standard CP 88 was prepared by the Technical Committee on TemporaryElectrical Installations under the direction of the Electrical Industry Practice Committee.

It was developed as a result of a review of the Singapore Standard CP 44 : 1988 Code of practicefor temporary electrical installations for construction and building sites.

This Part of CP 88 is drawn up to supplement the general requirements of Singapore Standard CP 5 Code of practice for electrical installations. As installations operating at voltages up to 1000 V a.c.are widely used in construction and building sites, it is considered necessary to give guidance on goodpractice for the inspection, testing and maintenance of such installations. In addition, guidance on theinstallation of generating set and socket-outlet assembly are included to address the common use ofgenerating set and socket-outlets for portable tools at these sites.

It is to be noted that for installations where separated extra low voltage (SELV) is used, referencesshall be made to the general requirements for protection by SELV in Singapore Standard CP 5.

Installations operating at voltages exceeding low voltage are outside the scope of this Part of theCode.

NOTE Temporary electrical installations other than that for Construction and Building Sites may be covered inother Parts of this Code.

Acknowledgement is made for the use of information from the following publications:

AS 2790 : 1989 Electricity generating sets Transportable (Up to 25 kW)

AS 3010.1 : 1987 Electrical installations Supply by generating setPart 1 Internal combustion engine driven set

BS 4363 : 1998 Specification for assemblies for reduced low voltage electricity supplies forconstruction and building sites

BS 4444 : 1989 Guide to electrical earth monitoring and protective conductor proving

BS 5345 : - Code of practice for selection, installation and maintenance of electricalapparatus for use in potentially explosive atmosphere (other than miningapplications or explosive processing and manufacture)

BS 6500 : 2000 Specification for electric cables Flexible cords rated up to 300/500 V, foruse with appliances and equipment intended for domestic, office and similarenvironments

BS 6708 : 1998 Flexible cables for use at mines and quarries

BS 7375 : 1996 Code of practice for distribution of electricity on construction and buildingsites

Clauses that are extracted from the above British Standards are given in Annex E. They arereproduced with the permission of British Standards Institution (BSI).

NOTE

1. Singapore Standards are subject to periodic review to keep abreast of technological changes and newtechnical developments. The revisions of Singapore Standards are announced through the issue ofeither amendment slips or revised editions.

2. Compliance with a Singapore Standard does not exempt users from legal obligations.


CP 88 : Part 1 : 2001

9

Code of practice for temporary electrical installations Part 1:Construction and building sites

1 General

1.1 Scope

This Part of the Code of Practice deals principally with temporary electrical installations for buildingoperation and work of engineering construction. It applies to electrical installations set up for theprovision of electricity supply during the execution of the following works:

(a) New building construction;

(b) Repair, alteration, extension or demolition of buildings;

(c) Engineering construction;

(d) Earthworks;

(e) Other similar works.

The requirements in this Code shall not apply to installations in construction site offices, meetingrooms, canteens, dormitories, toilets, etc., where the general requirements in the Singapore StandardCP 5 shall apply.

Although some temporary installations at these sites may receive supplies at voltages higher than1000 V, such parts of the installations are outside the scope of this Code.

This Code also does not cover those aspects of installations in compressed air environment andpotentially explosive atmospheres. NOTE The titles of the publications referred to in this standard are listed at the end of the standard.

1.2 Object

The object of this Part of the Code is to protect persons and property against electrical hazards in theuse of electricity in construction sites in view of the arduous duty imposed on the electrical equipmentand wiring by the construction site conditions.

The general requirements of Singapore Standard CP5 shall be read in conjunction with this Part of theCode.

Because of variations in local circumstances of construction sites, the requirements of this Code aregiven in general terms, and will normally need to be supplemented by the advice of skilled persons asdefined in 2.7.

1.3 Relationship with statutory regulations

This Part of the Code is to be implemented in conjunction with other statutory requirements currently inforce in the Republic of Singapore and should there be any conflicting requirements in the Acts andtheir Regulations, clarification should be obtained from the relevant bodies administrating the Acts andRegulations.


CP 88 : Part 1 : 2001

10

All temporary electrical installations for building operation and work of engineering construction arerequired to be licensed by the Public Utilities Board under the Public Utilities (Licence to Use orOperate Electrical or Supply Installations) Regulations.

1.4 Use of established materials, equipment and methods

Only established materials, equipment and methods are considered, but it is not intended todiscourage invention or to exclude other materials, equipment and methods affording an equivalentdegree of safety which may be developed in the future.

1.5 New materials and inventions

Where the use of a new material or invention leads to departures from this Part of the Code, theresulting degree of safety of the installation is to be not less than that obtained by compliance with thisPart of the Code. Such departure shall be the subject of a written specification of a competent body,or skilled person or persons, and the installation shall be deemed to be outside the scope of this Partof the Code.

2 Definitions

For the purposes of this Code, the following definitions shall apply. Other terms not defined herein areused in the sense defined in Singapore Standard CP 5.

2.1 Cable coupler

A cable coupler is a means enabling the connection at will of two flexible cables. It consists of twoparts: -

(a) A connector, which is the part integral with, or intended to be attached to, the flexible cableconnected to the supply;

(b) A plug, which is the part integral with, or intended to be attached to, the flexible cableconnected to the equipment or to a connector.

The plug of a cable coupler is identical to the plug of a 'plug and socket-outlet'. In general, a connectorhas the same contact arrangement as a socket-outlet.

2.2 Earth monitoring system

A system for providing a means of maintaining a high degree of confidence in the measuredimpedance of a protective conductor forming part of the earthing arrangements of an electricalsystem.

2.3 Generating set

A generating set is an internal combustion engine driving a rotating a.c. electrical generator togetherwith its associated control panel, switchgear and ancillary equipment, whether integrally mounted orotherwise.

2.4 Plug

A device, provided with contact pins, which is intended to be attached to a flexible cable, and whichcan be engaged with a socket-outlet or with a connector.


CP 88 : Part 1 : 2001

11

2.5 Protective conductor proving system

A system for providing a means of maintaining a high degree of confidence in the continuity of aprotective conductor within the installation.

2.6 Readily accessible

Capable of being reached quickly, for operation, renewal, or inspection without requiring those towhom ready access is requisite to climb over or remove obstacles or to resort to portable ladders,chairs, etc.

2.7 Skilled person

A person who is licensed as an electrical worker under the Electrical Workers and ContractorsLicensing Act.

2.8 Site

An area where a building operation or work of engineering construction takes place.

2.9 Socket-outlet

A device, provided with female contacts, which is intended to be installed with the fixed wiring, andintended to receive a plug. A luminaire track system is not regarded as a socket-outlet system.

2.10 Supplies

All references throughout this Code refer to alternating current (a.c.) supplies related to a frequency of50 Hz unless otherwise stated. All references to alternating voltage and current relate to r.m.s. valuesunless otherwise stated.

3 General requirements

3.1 Source of supply

3.1.1 General

Electrical installation at site may draw its supplies from the public electricity supply network orgenerating sets. Equipment shall be identified with and be compatible with the particular supply fromwhich it is energised and shall contain only components connected to one and the same installation,except for control of signalling circuits and inputs from standby supplies. Due consideration shall begiven to the fault level (prospective short-circuit current) at the point of supply.

3.1.2 Types of supply

3.1.2.1 Mains voltages of public supply system

(a) Three-phase. 400 V is the standard three-phase mains supply system voltage at 50 Hz.

(b) Single-phase. 230 V is the standard single-phase mains supply system voltage at 50 Hz.

3.1.2.2 Supply voltage from generating sets

For a generating set supplying low voltages, unless otherwise approved by the skilled personresponsible for the design and installation of supply installation, the output voltages shall be as follows:


CP 88 : Part 1 : 2001

12

(a) Three-phase. 400 V between phases, and 230 V between phases and Earth, 50 Hz.

(b) Single-phase. 230 V between phase and Earth, 50 Hz.

3.1.2.3 Reduced voltage

110 V single-phase. The supply shall be obtained from a double-wound transformer having thecentre tap of the secondary winding earthed so that the nominal voltage to Earth is only 55 V.

3.1.2.4 Extra low voltage

50 V single-phase. The supply shall be obtained from a double-wound transformer having thecentre tap of the secondary winding earthed so that the nominal voltage to Earth is only 25 V.

3.1.3 No parallel operation of generating set and the public electricity supply system

No parallel operation of the generating set and the public supply system shall be allowed unlessotherwise approved by the public electricity supplier. In a service area where electricity supply is takenfrom a generating set, no electricity supply from the public supply system shall be introduced into thesame service area.

3.1.4 Supply for equipment

The following voltages shall not be exceeded:

(a) Fixed plant, moveable plant fed via a trailing cable,installations in site buildings such as site offices,workshops, canteens and quarters, fixed flood lightingand site lighting.

400 V230 V

Three-phase, orSingle-phase

(b) Portable electric hand-held tools and portable hand-lamps.

230 V Single-phase

(c) Portable electric hand-held tools and portable hand-lamps used underground such as any shaft, tunnel,caisson or cofferdam.

110V Single-phase,centre pointearthed

(d) Portable electric hand-held tools and portable hand-lamps used in confined locations such as the insides ofboilers, tanks or pipes, or in other similar situations.

50V Single-phase,centre pointearthed

3.2 Type of earthing arrangement

3.2.1 The earthing system for electrical installations drawing supply from generating sets shall beTN-S.

3.2.2 If more than one generating set are used within a site, the electrical installations shall either:

(a) Share a common earthing system; or

(b) Have separate earthing systems and the electrical installations connected to different earthingsystems are segregated effectively from one another or effectively bonded to preventdangerous potential rise between conducting parts which a person can come intosimultaneous contact.

This requirement also applies to more than one electrical installations taking supply from the publicsupply system within the same site.


CP 88 : Part 1 : 2001

13

3.2.3 The design, selection and installation of protective conductors shall be in accordance withSingapore Standard CP 5.

3.3 Installation of generating set

3.3.1 General

Generating set shall be suitably barricaded to prevent access by non-authorised persons. Adequateclearance around generating set shall be provided to facilitate operation and maintenance work.Access leading to the generating sets shall be unimpeded to the skilled person or his representativesat all times. Any switch or control for stopping and starting the engines shall be readily accessible. Inaddition, generating set shall not be installed:

(a) In damp situations or exposed to the weather unless suitably protected; or

(b) In hazardous areas, unless the equipment and method of installation complies with BS 5345and the additional requirements of any relevant authority.

Care shall be taken to have the fuel and its containers stored in a safe manner.

3.3.2 Earthing arrangements of generating set

Electrical installation supplied from generating sets shall share a common TN-S earthing system withthe generator or generators connected to it. In any electrical installation, a main earthing terminal orbar of adequate rating shall be provided and connected to the earthing conductors. The star point of athree-phase generator winding or the mid-point of a single-phase centre-tapped generator windingshall be solidly earthed through adequately rated conductors to the earthing system of the installation.

In addition, the following parts of the generating sets shall be bonded together to form the generatorbonding system which shall be connected effectively to the main earthing terminal:

(a) The engine frame;

(b) The generator frame;

(c) All exposed metal enclosure for electrical equipment and wiring;

(d) Earth terminals of all socket-outlet (if any); and

(e) The main frame terminal (marked )

3.3.3 Protection against direct contact of live parts

All live parts of a generating set shall be protected against direct contact in accordance with SingaporeStandard CP 5.

3.3.4 Labelling on generating set

The following information shall be indelibly and legibly marked on a generating set:

(a) The name of the manufacturer of the set;

(b) The model number and serial number of the set;

(c) The type of fuel or fuel-oil mixture;

(d) Rated output in watts or kilowatts at a stated power factor;


CP 88 : Part 1 : 2001

14

(e) The voltage and frequency;

(f) Output terminal markings (unless all outputs are socket-outlets);

(g) The frame terminal : symbol marked ;

(h) On a set intended for undercover or weather-protected usage, the words NOT WEATHER-PROOF;

(i) On a set intended for outdoor use without further protection, the IP classification of itselectrical equipment;

(j) In addition, a danger sign board made of durable material with the word DANGER with thespecification as detailed in Annex D shall be displayed at a prominent location near thegenerating set.

4 Protection for safety

4.1 Control of supply

4.1.1 General

Every electrical installation on construction sites shall be adequately controlled by switchgear readilyaccessible to the skilled person or his authorised representative in charge of the installation and shallincorporate:

(a) Means of isolation;

(b) Means of overcurrent and earth fault protection; and

(c) Means of earth leakage protection (except extra-low voltage installations)

4.1.2 Protective device for incoming supply

For an incoming supply up to 300 A three-phase, a circuit breaker with residual current device shall beprovided at the main switchboard.

For an incoming supply exceeding 300 A three-phase, a circuit breaker incorporating overcurrent andearth fault protective devices shall be provided.

4.1.3 Protection of circuits

Appropriate electrical protection shall be provided for all circuits, including final circuits, againstoverload, short-circuit and earth-fault current. The protective devices shall be capable of interruptingwithout damage any fault current that may occur and due consideration shall be given to the fault levelof the supply.

4.1.4 Prohibited use of fuses for final circuits

Fuses shall not be used for protecting final circuits in any part of the installation, except for thosesocket-outlets incorporated with fuse protection.


CP 88 : Part 1 : 2001

15

4.2 Protection against direct contact

One or more of the following basic protective measure shall be used in accordance with therequirements in Singapore Standard CP 5:

(a) Protection by insulation of live parts,

(b) Protection by a barrier or an enclosure,

(c) Protection by obstacles,

(d) Protection by placing out of reach.

4.3 Protection against indirect contact for low voltage system

4.3.1 General

Protection against indirect contact for low voltage system shall comply with clauses 4.3.2 to 4.3.3.

4.3.2 Protection by residual current device

Protection against indirect contact shall be afforded using residual current devices and the followingcondition shall be fulfilled as appropriate to the type of earthing system:

For TN-S system: Zs In 25 Vwhere

Zs is the earth fault loop impedance in ohms

In is the rated residual operating current of the protective device in amperes.

For TT system: Ra In 25 Vwhere

Ra is the sum of the resistances of the earth electrode and the protective conductor(s)connecting it to the exposed-conductive-part.

4.3.3 Protection by residual current device for final circuits

Except for final circuits supplying equipment which are protected by other appropriate measures aspermitted under this Code and only accessible to and are operated by a skilled person, all other finalcircuits are to be protected by one or more residual current devices. The type and tripping sensitivitiesof residual current device to be used for the final circuit of the following rating shall be:

(a) Residual current circuit breaker with a tripping current not exceeding 30 mA and a trippingtime within 0.1 s complying with SS 97 for final circuits of rating not exceeding 63 A three-phase or single-phase at mains voltage.

(b) Residual current circuit breaker with a tripping current not exceeding 300 mA complying withSS 97 for final circuits of rating exceeding 63 A but not more than 100 A three-phase orsingle-phase at mains voltage.

(c) Residual current device with a tripping current not exceeding 500 mA shall be used for finalcircuits of rating exceeding 100 A three-phase at mains voltage.


CP 88 : Part 1 : 2001

16

4.3.4 Earth leakage protection for transportable electrical equipment

For guidance on earth leakage protection for transportable electrical equipment, refer to SingaporeStandard CP 16.

4.3.5 Protective conductor proving and earth monitoring systems

Where flexible cables supplying power at mains voltage to a moveable plant are liable to becomedamaged or discontinuous, a protective conductor proving and/or earth monitoring system shall beused to detect the failure of the circuit protective conductor. Annex B describes one such systemwhich is recommended to detect the failure of the circuit protective conductor.

4.4 Protection against indirect contact for reduced voltage system

Protection against indirect contact for reduced voltage system by automatic disconnection shall beprovided by means of an overcurrent protective device in each phase conductor or by a residualcurrent device, and all exposed-conductive-parts of the reduced voltage system shall be connected toEarth. The earth fault loop impedance at every point of utilisation, including socket-outlets, shall besuch that the disconnection time does not exceed 5 s.

Where a circuit breaker is used, the maximum value of the earth fault loop impedance (Zs) shall notexceed the values specified in Table 1 below for the nominal voltages to Earth (Uo) and for the typesand ratings of circuit-breaker listed herein.

Where a residual current device is used, the product of the rated residual operating current inamperes and the earth fault loop impedance in ohms shall not exceed 25.

Table 1 Maximum earth fault loop impedance (Zs) for adisconnection time 5s and Uo of 55 volts (single-phase)

MCB Type toSS 359 & BSEN 60898

1 B 2 C & 3 D

Ratingamperes (In) Uo / 4 ln Uo / 5 ln Uo / 7 ln Uo / 10 ln Uo / 20 ln

6 2.29 1.83 1.31 0.92 0.4610 1.38 1.10 0.79 0.55 0.2816 0.86 0.69 0.49 0.34 0.1720 0.69 0.55 0.39 0.28 0.1425 0.55 0.44 0.31 0.22 0.1132 0.43 0.34 0.25 0.17 0.0940 0.34 0.28 0.20 0.14 0.0750 0.28 0.22 0.16 0.11 0.0663 0.22 0.18 0.13 0.09 0.0480 0.17 0.14 0.10 0.07 0.03100 0.14 0.11 0.08 0.06 0.03

4.5 Protection against lightning

In circumstances where protection against lightning on sites may be necessary, reference shall bemade to Singapore Standard CP 33.


CP 88 : Part 1 : 2001

17

5 Selection and erection of equipment

5.1 General

Every item of equipment shall be selected and erected so as to comply with the general requirementsstipulated in the Singapore Standard CP 5 and the following clauses in this Section.

5.2 Wiring systems

The types of protective covering of cables used in all the site installations shall be selected inaccordance with subclauses 5.2.1 to 5.2.5.

5.2.1 5.2.6 Types of cable covering

5.2.1 All cables to be laid direct in the ground shall be armoured cables.

5.2.2 Except for cables installed overhead, all other cables for submains or final circuits operating atvoltages exceeding 63 V to Earth (Three-phase system) or 55 V to Earth (Single-phase system) androuted outdoor shall be of armoured construction and buried where possible.

5.2.3 All cables which are likely to be moved in normal use shall be flexible cables. Where trailingcables are required by nature of the work, they shall be of the armoured type complying with BS 6708having an over-sheath of heavy duty oil-resisting and flame-retardant compound.

5.2.4 Elevated cables shall be fully insulated having a sheath of PVC or an oil-resisting and flame-retardant or heat resisting sheath. Overhead cables exposed to sunlight shall comply with subclause5.2.6.

5.2.5 Except for situations (e.g. switch rooms or control rooms) where the risk of mechanicaldamage is slight, armoured cables having an over-sheath of PVC or an oil-resisting and flame-retardant compound or cables with adequate mechanical protection shall be used.

5.2.6 For resistance to the effects of sunlight, suitable non-metallic covering of cables shall beused.

5.2.7 5.2.10 Flexible cords

5.2.7 Flexible cords shall be of the circular type having heat resisting, oil resisting and flame-retardant rubber-sheath complying with IEC 60245 Part 1 or PVC insulated and PVC sheathedcomplying with SS 358 : Part 5.

5.2.8 Flexible cords for portable hand-lamps shall be of the circular type having screened Type EM2rubber-sheath complying with BS 6500.

5.2.9 Flexible cords of portable electrical equipment shall not exceed 3 m in length or such lengthas supplied by the original equipment manufacturer.

5.2.10 Flexible cords of conductor size smaller than 1.0 mm (32/0.20 mm) shall not be used.

5.2.11 5.2.26 Installation of cables

5.2.11 Cables, other than those supplying power to portable electrical equipment or mobile plant,shall be fixed on site so that they are clear of building operation or engineering construction work andare not a hazard to persons working on the site.

5.2.12 All cables are to be installed without obstruction to the use of passageways, walkways,ladders, stairs and the like.


CP 88 : Part 1 : 2001

18

5.2.13 Where submains cables inside a building or under a covered area are to be suspended orsupported from the ceiling or wall, cable trays, brackets or other suitable supports shall be provided.The cable supports shall not cause damage to the cable insulation or subject the cables to unduemechanical stress.

5.2.14 Laying of cables on the ground or the floor of a structure shall be avoided. Where it isunavoidable to lay cables on the ground or the floor of a structure, the cables shall be of the armouredtype complying with BS 6708 having an over-sheath of heavy duty oil-resisting and flame-retardantcompound or PVC insulated, steel wire armoured and PVC sheathed complying with SS 443 and shallbe laid in such a manner that the risk of mechanical damage is prevented.

5.2.15 Elevated flexible cables used indoor shall be provided with suitable mechanical protection andsecurely supported in such a manner as not to damage the sheath of the flexible cables and notsubject the cables or their terminations to undue mechanical stress.

5.2.16 No flexible cord shall be used as submain or final circuit for the purpose of distribution ofelectricity supply.

5.2.17 Cables buried direct in the ground shall be marked by cable covers and shall be buried at aminimum depth of 300 mm to avoid being damaged by any disturbance on the ground. The cableroute for all supply cables and submains buried underground shall be marked on site drawings.

5.2.18 Cables passing under roadways or accessways for transport and mobile plant shall be laid ata minimum depth of 600 mm. A cable marker shall be installed at both ends of each crossing.

5.2.19 Overhead cables shall be so placed and at such height as to be out of reach of any source ofmechanical damage reasonably to be foreseen in the area where they are erected. For cables to beinstalled outdoor, the requirement in subclause 5.2.6 shall be complied with.

5.2.20 Overhead cables shall be installed at a height such that a clear vertical distance between thelowest part of the overhead cables and the highest point of vehicles, mobile cranes or other mobileplant likely to pass underneath them is 2 m minimum but under no circumstances shall the clearheight to ground of the overhead cables be less than 5 m where they cross roadways or accessways.

5.2.21 Overhead cables shall be supported by catenary wires or proper cable support in a mannersuch that the cables are not subjected to undue mechanical stress. The catenary wires or metalliccable support shall be effectively bonded to Earth.

5.2.22 Poles supporting overhead cables shall be so located or arranged that the risk of mechanicalor vehicular damage is prevented. Poles shall be sufficiently sized with adequate mechanical strengthand properly anchored.

5.2.23 Metal pole of minimum diameter 100 mm with adequate mechanical strength shall be used.Poles made of wood or plastic material shall not be used for this purpose.

5.2.24 All cables shall be installed so that they are at least 150 mm clear of piped services such assteam, gas and water and shall not be located directly below and parallel to these pipes.

5.2.25 All armoured cable terminations shall be provided with cable glands and earth tags forbonding to associated gland plate and adjacent cables in order to maintain satisfactory earth loopimpedance. The armour of the cable shall not however be relied on as circuit protective conductor forthe cable.

5.2.26 All joints shall be mechanically and electrically sound and fully insulated.


CP 88 : Part 1 : 2001

19

5.3 Switchgear and controlgear

5.3.1 Enclosure for low-voltage assembly

5.3.1.1 The enclosure of each assembly for the distribution of electricity shall be robustly constructedso as to have adequate strength and rigidity to resist damage that could result from transportation,rough handling and heavy objects falling on it.

5.3.1.2 Except for socket-outlet assembly, the enclosure for outdoor installation shall have:

(a) A degree of protection of at least IP44 to ensure the safe and satisfactory operation of theenclosed equipment; and

(b) A roof so designed to prevent stagnation of water on its surface.

NOTE It is recommended that the roof shall extend at least 76 mm beyond the main body of the enclosure.

5.3.1.3 The enclosure shall be so placed, installed and safeguarded:

(a) To prevent damage by external influences that may affect the design and safe operation of theequipment; and

(b) Shall be provided with adequate and safe means of access and working space for operationand maintenance purposes.

5.3.2 Switchboard and distribution board

5.3.2.1 Every switchboard and distribution board shall incorporate means for isolating and switchingthe incoming supply. Isolating switches or circuit breakers used for this purpose shall be suitable forsecuring in the OFF position.

5.3.2.2 Every switchboard and distribution board shall be erected to satisfy the requirements ofClause 4 of this Code.

5.4 Socket-outlets assembly

Socket-outlet assembly shall be used for the connection of portable electrical equipment at locationswhere fixed socket-outlets may not be available. The assembly shall fulfil the requirements describedin subclause 5.4.1 to 5.4.5.

5.4.1 Enclosure for socket-outlet assembly

5.4.1.1 The enclosure for the socket-outlet assembly shall be fabricated from:

(a) Galvanised sheet steel of minimum 1.5 mm thickness finished in epoxy powder coating; or

(b) Aluminium sheet of minimum 2 mm thickness finished in epoxy powder coating; or

(c) Self-extinguishing, non-hygroscopic polycarbonate thermoplastic with high impact strength(6 joule), high resistance to UV rays, high resistance to chemical elements and highresistance to abnormal heat and fire (glow wire test according to SS 145 Part 2)

As amendedMay 2001

5.4.1.2 The degree of protection for the enclosure shall be of minimum IP44 to SS IEC 60529.

5.4.1.3 The enclosure can be of floor standing or wall mounting and shall be totally enclosed with alllive parts protected from direct contact. Floor standing socket-outlet assembly shall be:

(a) Fitted with supports to afford a minimum clearance of 150 mm from the ground; and


CP 88 : Part 1 : 2001

20

(b) Provided with handles and lifting lugs.

5.4.1.4 Every cable connection to and from the enclosure shall be by means of plugs and socket-outlets. The plugs and socket-outlets shall be of the appropriate type specified in subclause 5.5.

5.4.2 Single-phase socket-outlet assembly fed from single-phase source

5.4.2.1 The assembly shall be fed from a 32 A single-phase 230 V source.

5.4.2.2 A fixed plug rated at 32 A single-phase 230 V shall be provided to receive the 32 A single-phase 230 V incoming supply. A 32 A double-pole MCB shall be provided to control the incomingsupply.

5.4.2.3 A maximum of up to six numbers of 16A 2-pole and earth socket-outlets shall be provided.Each socket-outlet shall be controlled by a double-pole MCB not exceeding 16 A current rating. Allsocket-outlets shall be protected by residual current circuit breaker complying with SingaporeStandard SS 97 having a rated residual current not exceeding 30 mA.

5.4.3 Single-phase socket-outlet assembly fed from three-phase source

5.4.3.1 The assembly shall be fed from a 32 A three-phase 400 V source.

5.4.3.2 A fixed plug rated at 32 A three-phase 400 V shall be provided to receive the 32 A three-phase400 V incoming supply. A 32 A 4-pole MCB shall be provided to control the incoming supply.

5.4.3.3 A maximum of nine numbers of 16 A 2-pole and earth socket-outlets shall be provided. Eachsocket-outlet shall be controlled by a double-pole MCB not exceeding 16 A current rating. All socket-outlets shall be protected by residual current circuit breaker complying with Singapore Standard SS 97having a rated residual current not exceeding 30 mA.

5.4.4 Three-phase socket-outlet assembly



5.4.4.3 A maximum of three numbers of 16 A 4-pole and earth socket-outlets shall be provided. Eachsocket-outlet shall be controlled by a TP&N MCB not exceeding 16 A current rating. All socket-outletsshall be protected by residual current circuit breaker complying with Singapore Standard SS 97 havinga rated residual current not exceeding 30 mA.

5.4.5 Three-phase and single phase socket-outlet assembly



5.4.5.3 A maximum of two numbers of 16 A 4-pole and earth socket-outlets and a maximum of threenumbers of 16 A 2-pole and earth socket-outlet shall be provided. Each socket-outlet shall becontrolled by a TP&N MCB / double-pole MCB of current rating not exceeding 16 A. All socket-outletsshall be protected by residual current circuit breaker complying with Singapore Standard SS 97 havinga rated residual current not exceeding 30 mA.

5.4.5.4 The schematic connection arrangements of the socket-outlet assemblies are shown in Figures1 to 4.


CP 88 : Part 1 : 2001

21

Figure 1 Example of single-phase socket-outlet assembly fed from single-phase source

Figure 2 Example of single-phase socket-outlet assembly fed from three-phase source


CP 88 : Part 1 : 2001

22

Figure 3 Example of three-phase socket-outlet assembly

Figure 4 Example of three-phase and single-phase socket-outlet assembly


CP 88 : Part 1 : 2001

23

5.5 Plugs, socket-outlets and cable couplers

5.5.1 All plugs, socket-outlets and cable couplers shall comply with the requirements of IEC 60309.

5.5.2 All plugs, socket-outlets and cable couplers likely to be exposed to the weather shall becontained in a weatherproof enclosure unless they are of the weatherproof type (minimum IP44 to SSIEC 60529).

5.5.3 Plugs of one voltage system shall not be capable of entering socket-outlets of other voltagesystems used in the same site.

5.5.4 Plugs, socket-outlets and cable couplers of a 110 V single-phase operation shall be of the 3-pin type and the numbered hour position shall be 4H.

NOTE Numbered hour position indicates the position of earth contact-tube in relation to the keyway.

5.5.5 Plugs, socket-outlets and cable couplers for use with 230 V single-phase system shall be ofthe 3-pin type with the numbered hour position 6H.

5.5.6 Plugs, socket-outlets and cable couplers for use with 400 V three-phase system shall be ofthe 5-pin type, 3-pole and neutral and earth, and numbered hour position 6H.

5.5.7 Where several voltages are used in the temporary installation, all plugs, socket-outlets andcable couplers shall be identified by different colours as given in Table 2.

Table 2 Colour coding

Operating Voltage (V) Colour55

110230400

WhiteYellowBlueRed

5.5.8 5.5.9 Connection to socket-outlets

5.5.8 Connection of flexible cables or flexible cords to socket-outlets shall be by means of plugs.

5.5.9 Where heavy electrical plants such as rail-mounted tower cranes requires the use of plugsand socket-outlets as a convenient form of connection at mains, such plugs and socket-outlets shallbe mechanically interlocked. Electrical interlock can be used as an additional feature.

5.6 Cable for SOA Connection

An extension cable may be used to connect portable equipment to a SOA and such extension cableshall comply with the following conditions:

(a) the cable shall be appropriately sized and provided with suitable mechanical protection;

(b) the cable shall be connected to an industrial plug of appropriate rating on one end and aswitched industrial socket-outlet at the other end to facilitate emergency switching; and

(c) the industrial plug and switched socket-outlet shall be as specified in clause 5.5.


CP 88 : Part 1 : 2001

24

5.7 Earthing arrangement and protective conductor

Every earthing arrangement and protective conductor shall be selected and erected to comply with therequirements of the Singapore Standard CP 5. Attention shall also be paid to the need forequipotential bonding of extraneous metallic parts.

5.7.1 Protective earthing of metalwork

Metalwork not belonging to the installation including steel scaffolding which is liable to come intofortuitous contact and become live in the event of a failure of insulation of the installation shall beeffectively earthed at all times.

5.7.2 Earthing of portable appliances and tools

Exposed metalwork of all portable appliances and tools shall be connected to the circuit protectiveconductors in the flexible cables or flexible cords unless they are double-insulated as specified in SS236 or of extra-low voltage system. For further guidance, refer to the appropriate clause in SingaporeStandard CP 16 on earthing of portable appliances and tools.

5.7.3 Earthing of metal sheath and armour of cables

Metal sheath and armour of cables shall be effectively earthed. However, the metal sheath or armourof the cable shall not be used as circuit protective conductor.

5.7.4 Metal sheath and/or armour of flexible or trailing cables

Metal sheath and/or armour of flexible or trailing cables shall not be the sole circuit protectiveconductor but in addition to the earth cores of the cables.

5.7.5 Earthing of metal enclosure for switchboards and distribution boards

Constructional precautions shall be taken to ensure electrical continuity between the exposedconductive parts of the switchboard and distribution boards and between these parts and theprotective circuits of the installation.

5.8 Other equipment

5.8.1 Light fixtures

Light fixtures used outdoor or at locations where there is likelihood that such fixtures are subjected towater splashing shall be of the weatherproof type. Light fixtures installed shall be equipped withsuitable guards if they are exposed to risk of mechanical damage.

5.8.2 Portable hand-lamps

Portable hand-lamps supplied through flexible cords shall be of the moulded composition or other typedesigned for the purpose and equipped with a handle. Hand-lamps shall also be equipped withsubstantial guard attached to the lampholder or the handle.

5.8.3 Prohibited use of lampholders fitted with pin contacts

The use of lampholders fitted with pin contacts intended to be penetrated into tough rubber sheath orpolychloroprene sheath cable is prohibited.


CP 88 : Part 1 : 2001

25

5.8.4 Electrical welding system

Every a.c. welding set must be equipped with low voltage shock preventor. The preventor shalleffectively reduce the open circuit secondary voltage to a safe level not exceeding 25 V.

The low voltage shock preventors shall be of the built-in type or be housed in a weatherproof metalcasing and effectively secured or locked to prevent tampering by welders and other unauthorisedpersons. The workpiece should be connected to the return terminal of the welding set through aproper return conductor.

5.9 Equipment for reduced voltage system

5.9.1 Plug, socket-outlet and cable coupler of a reduced voltage system

Every plug, socket-outlet and cable coupler of a reduced voltage system shall have a protectiveconductor contact and shall not be dimensionally compatible with any plug, socket-outlet or cablecoupler for use at any other voltage or frequency in the same installation.

5.9.2 Switches for reduced voltage circuits

Switches controlling single-phase supplies on installations operating up to and including 110 V shall beof the double-pole type with circuit protection provided in each line conductor.

6 Inspection, testing and maintenance

6.1 Electrical installation on site shall be inspected and tested in accordance with therequirements of Part 7 Inspection and Testing of Singapore Standard CP 5 before installation isenergised.

6.2 Strict maintenance and periodic inspection of the electrical installation and the wiringdistribution system shall be carried out by a skilled person to promote safety and to ensure efficientoperation.

6.3 All temporary electrical installations shall be inspected by a skilled person at least once amonth. Upon completion of the inspection, the skilled person shall complete and sign the checklistshown in Annex C and hand it over to the operator of the electrical installation or his representative.

6.4 Where any defect or unsafe condition is revealed during the inspection, the skilled personshall take measures, such as by rectifying the defects, or by isolating or disconnecting the defectivepart or parts from electricity supply, to render the electrical installation safe. Appropriate measurestaken shall be clearly indicated in the checklist.


CP 88 : Part 1 : 2001

26

Annex A

Statutory regulations and associated memoranda

In the Republic of Singapore, temporary electrical installations are required to comply with the statutoryregulations indicated below. The Regulations listed represent the principal legal requirements.Information concerning those regulations may be obtained from the appropriate authority alsoindicated below.

(i) Public Utilities Act Public Utilities Board

(ii) Public Utilities (Electricity) Public Utilities BoardRegulations

(iii) Public Utilities (Electricity Supply) Public Utilities BoardRegulations

(iv) Public Utilities (Licence To Use Public Utilities Boardor Operate Electrical or SupplyInstallations) Regulations

(v) Electrical Workers and Public Utilities BoardContractors Licensing Act

(vi) Factories Act (Chapter 104) Occupational Safety DeptMinistry of Manpower

(vii) Factories (Building Operations and Occupational Safety DeptWorks of Engineering Construction) Ministry of ManpowerRegulations


CP 88 : Part 1 : 2001

27

Annex B

Protective conductor proving and earth monitoring systems

The use of flexible cables to supply power at mains voltages to moveable plant introduces specialsafety problems in ensuring the continuing efficiency of the earth return path. If the circuit protectiveconductor incorporated in the cable becomes damaged or discontinuous, it will no longer provide asound metallic return path for the fault current should an earth fault occur.

Earth monitoring and/or protective conductor proving may be employed to alleviate this situation.

B.1 Protective conductor proving system A protective conductor proving system provides a means of establishing a degree of confidence in thecontinuity of the protective conductor from the proving unit to remote protected apparatus. Noprovision is made for impedance measuring but designs centred around the use of specialised relaysafford a coarse method of proving. The proving unit may be connected anywhere between the origin of the installation and the apparatusto be protected. Detection of short circuits between pilot and protective conductors may be achieved by the use of d.c.sensitive relays as a part of the proving system. Continuity may be proved with a shunt connectedvoltage sensing device or a series connected current sensing device. In either case the protectiveconductor should be a substantial earth path of low impedance. The impedance of the source anddetector combination Z1 (see figure B1) should appear in series with the pilot earth path. The totalimpedance of the monitored loop is the algebraic sum of the impedance Z1 and the impedance of therest of the loop Z2. A value Z2 in excess of about 10 should prevent the load apparatus beingenergised. Furthermore, after the apparatus has been energised, if the monitored loop becomesopen-circuited or increases in impedance beyond about 20 the apparatus should become isolated. NOTE The impedance values quoted are only examples and the actual values need to be considered in thelight of specific applications. The proving current circulates in a loop circuit which contains the protective conductor to theapparatus, a section of the apparatus casing and a suitable return path. It is essential that any plugand socket and flexible cable therefore provide not only the main protective path but also a return pathwhich is usually known as a pilot conductor. It is essential that the proving unit itself be properly earthed in accordance with SS CP 16. The factthat the earth loop contains a section of the apparatus casing, necessitates the provision of the twoindependent earth terminals on the casing, otherwise there would be a risk of both conductorsbecoming detached from the casing whilst still maintaining the monitored loop. It is worth noting thatalthough the main and pilot paths are monitored in series, they function in parallel as far as actualearth-fault currents are concerned.


CP 88 : Part 1 : 2001

28

B.2 Earth monitoring system

An earth monitoring system provides a means of maintaining a high degree of confidence in theimpedance level of the protective conductor from the monitoring unit to the remote protectedapparatus. The monitoring unit may be connected between the source of energy (if accessible) andthe apparatus to be protected.

NOTE The source of energy may be, for example, a generator or a transformer.Earth monitoring depends upon continuous circulation of a small current at a voltage not exceeding12 V derived from a safety extra low voltage source. An interruption of this current is arranged to bringabout disconnection of the protected apparatus from the supply. The monitoring current circulates in aloop circuit which contains the protective conductor to the apparatus, a section of the equipmentcasing and a suitable return path.

It is therefore essential that any plug and socket and flexible cable provide not only the main protectivepath but also a return path which is usually known as the pilot conductor.

It is worth noting that although the main and pilot paths are monitored in series, they function inparallel as far as actual earth-fault currents are concerned. It is essential that the monitoring unit beearthed in accordance with SS CP 16. The fact that the earth loop contains a section of the apparatuscasing, necessitates the provision of two independent earth terminals on the casing, otherwise therewould be a risk of both conductors becoming detached from the casing whilst still maintaining themonitored loop.

The impedance of the protective and pilot conductors forms part of a balanced bridge network (seefigure B2). The balance is disturbed by variations in the parameters of the loop (e.g. open circuit orshort circuit) and this can initiate a signal or disconnection.

Typical impedance sensitivity of the balanced bridge network (in the temperature range -10oC to +4oC)is 8 2 .NOTE Further information on earth monitoring and protective conductor proving is given in BS 4444.


CP 88 : Part 1 : 2001

29

ORIGIN

Key

E1 Protective earth terminalE2 Earth terminal for pilot circuit (this may be internal or external)P Pilot conductor terminalS Sensing deviceV Extra low voltage sourceZ1 Impedance of sourceZ2 Impedance of the loops

NOTE If a diode is not used then a link has to be provided for a direct connection between terminals P and E2.

Figure B1 Basic circuit for protective conductor proving unit

V

SDiode(optional)

Z1 Z2

E1

P

E2

Apparatus

L

N

L

N

E

N N

L L

Proving Unit

Loadterminals

Supplyterminals

P

E

V

S


CP 88 : Part 1 : 2001

30

ORIGIN

Key

B Balancing sensing networkE1 Protective earth terminalE2 Earth terminal for pilot circuit (this may be internal or external)P Pilot conductor terminalZ1 Impedance of sourceZ2 Impedance of the loops

Figure B2 Basic circuit for earth monitoring unit

DiodeZ1 Z2

E1

P

E2

Apparatus

L

N

L

N

E

N N

L L

Monitoring Unit

Loadterminals

Supplyterminals

P

E

B


CP 88 : Part 1 : 2001

31

Annex C

Temporary electrical installations inspection checklistfor construction and building sites

Site : __ _______ _______

Date of inspection : _____________

Installation Licence No : ________ ____ Expiry Date : _____________

(1) SINGLE LINE DRAWINGS (Minimum A3 size)

Drawing No(s) _________________________________ submitted previously on

_______________________ is/are still valid.

New drawing which shows details of loads and circuits are enclosed.

Drawing No. ___________________________________________

(2) POWER SOURCE

From public electricity supply system:Approved load = ____________________ KVA

Incoming circuit breaker rating = ____________________ A

From Generating Set: Details of generating sets are as follows:

Particulars Gen Set 1 Gen Set 2 Gen Set 3 Gen Set 4Serial No.

Phase to PhaseSupplyVoltage(V) Phase to Earth

Rated KVAPower FactorFrequency (Hz)Fuel UsedMains Circuit Breaker Rating (A)

(3) DISTRIBUTION VOLTAGES USED (tick accordingly)

400 V 3, 230 V single ,110 V single , 55 V single


CP 88 : Part 1 : 2001

32

(4) EARTHING ARRANGEMENT ComplianceC NC NA

4.1 For double-wound 110V 1 transformer, centre tap ofsecondary winding is earthed.

4.2 The type of earthing system for electrical installationsupplied from generating set, is TN-S.

4.3 Main earthing terminal or bar is adequately sized andproperly installed.

4.4 Earth inspection chamber is accessible for inspection.

4.5 Bonding of metallic parts, where applicable, is adequate.

(5) GENERATING SET

5.1 Barricaded to prevent access by non-authorised persons.

5.2 Adequate working space around generating set.

5.3 Access to generating set not impeded.

5.4 Generating set not installed in damp or exposedconditions.

5.5 Generating set not installed in hazardous location.

5.6 All live parts protected against direct contact.

5.7 Adequately sized earthing bar or terminal is provided.

5.8 Proper labelling of earthing conductors provided.

5.9 For 3 generator > 55 V, star-point is earthed.5.10 For 1 generator > 55 V, neutral is earthed.5.11 Engine frame and generator frame bonded to earth.

5.12 Bonding of metallic parts, where applicable, is adequate.

5.13 All outgoing supply cables provided with overcurrent andearth fault protection.

5.14 Protective devices are in operating condition.

(6) MAINS INCOMING SUPPLY AND EARTHLEAKAGE PROTECTION

6.1 For incoming supply 300 A 3, a circuit breaker withresidual current device is used.


CP 88 : Part 1 : 2001

33

ComplianceC NC NA

6.2 For incoming supply > 300 A 3, a circuit breaker withovercurrent and earth protective devices are used.

6.3 Residual current circuit breaker with tripping current 100 mA operates within 0.1 s at rated tripping current.

6.4 Earth fault loop impedance is tested for satisfactoryoperation against indirect contact.

6.5 Overall insulation resistance 0.5 M(a) phase to phase,(b) phase to earth,(c) phase to neutral,(d) neutral to earth.

6.6 Earthing conductor is appropriately sized and properlyterminated.

6.7 Warning signs are displayed at main generating set andmain intake switchboard.

(7) DISTRIBUTION BOARD (DB) As amendedMay 2001

7.1 DB is properly installed and earthed.

7.2 Submains cables are properly terminated and installed.

7.3 DB is properly labelled.

7.4 Good protective conductor continuity.

7.5 Warning signs are displayed at distribution boards.

7.6 All outdoor cables are of armoured construction.

7.7 No metal sheath or armour of any cable is used as circuitprotective conductor.

(8) FINAL CIRCUITS

8.1 For final circuits 63 A, RCCB with tripping current 30mA operates within 0.1 s.

8.2 For final circuits exceeding 63 A but not exceeding 100A,RCCB with tripping current 300 mA operates within0.1s.

8.3 For final circuits > 100A, a RCD with tripping current notexceeding 500mA is provided.

8.4 Insulation resistance to earth of each final circuit 1 M.


CP 88 : Part 1 : 2001

34

ComplianceC NC NA

8.5 Polarity at all socket-outlets is correct.

8.6 All flexible cords, switches, plugs and socket outlets arein good and serviceable condition.

8.7 Rewireable fuses are not used except for socket-outletincorporated with fuses.

8.8 All switches for 1 supply 110 V shall be of double-pole type with protection in each live conductor.

8.9 Colour codes of plug, socket-outlet and cable coupler ofdifferent operating voltages are correct.

8.10 All cables are properly supported.

8.11 Circuit protective conductor is provided for each finalcircuit.

8.12 No flexible cord is used as fixed wiring.

(9) SOCKET-OUTLET ASSEMBLY

9.1 Socket-outlet assembly is properly installed and earthed.

9.2 Socket-outlet assembly is the recommended type.

9.3 Incoming is a fixed plug (male)

9.4 Outgoing outlets are fixed sockets

9.5 Each fixed socket-outlet protected by approved typeresidual current circuit breaker (RCCB), current rating notexceeding 30 mA and a MCB.

(10) ENVIRONMENTAL CONDITIONS

10.1 Unimpeded access to the main switchboard

10.2 Switchroom locking facilities are provided

10.3 Switchroom shows no sign of water leakage or seepage

10.4 Lighting for switchboard is adequate

10.5 Switchroom ventilation is adequate

10.6 Switchroom is not used for storage

10.7 Switchroom free of vermin and rodents


CP 88 : Part 1 : 2001

35

(11) GENERAL OBSERVATIONS

Tick accordingly: C ComplyNC Non ComplyNA Not Applicable

(12) DECLARATION BY LICENCE ELECTRICAL WORKER (SKILLED PERSON)

I declare that the electrical installation is * fit and safe / unfit and unsafe for operation.

* Please delete as appropriate.

Name of LEW : _________________________________ Licence No :

Signature : _________________________________ Date :

The inspection was witnessed by owner / operator of the electrical installation.

Name ofRepresentative :

Designation :

Signature : Date :


CP 88 : Part 1 : 2001

36

Annex D

As amendedMay 2001 Danger signboard

NOTE The danger signboard shall have the word DANGER and the operating voltage of the equipmentinscribed:

(a) In block characters of at least 30 mm high and 5mm wide; and(b) In the English, Malay, Chinese and Tamil languages; and(c) In black against a yellow background; and(d) Be maintained in a clear and legible condition at all times.

It is recommended that the dimensions of the signboard be at least 280mm x 400mm.

280mm

400mm


CP 88 : Part 1 : 2001

37

Annex E

Clauses that are extracted from British standards

Clause no. Clause Title British Standard BS Clause no./Title2.2 Earth monitoring system BS 4444 : 1989 2.2 Earth monitoring system2.8 Site BS 4363 : 1998 2.1 Site

3.1.2.2 Supply voltage fromgenerating sets

BS 7375 : 1996 3.5.1 Electrical protection ofcircuit. General

4.1.3 Protection of circuits BS 7375 : 1996 3.5.1 Electrical protection ofcircuit. General

4.3.5 Protective conductor provingand earth monitoring systems

BS 7375 : 1996 3.5.5 Protection conductorproving and earth monitoringsystems

Annex B Protective conductor provingand earth monitoring systems

BS 4444 : 1989

BS 7375 : 1996

3 Earth proving systems4 Earth Monitoring system3.5.5.1 to 3.5.5.3


CP 88 : Part 1 : 2001

38

Standards referred to:

AS 2790 : 1989 Electricity generating sets Transportable (Up to 25 kW)

AS 3010.1 : 1987 Electrical installations Supply by generating setPart 1 Internal combustion engine driven set

BS 4363 : 1998 Specification for distribution assemblies for reduced low voltage electricitysupplies for construction and building sites

BS 4444 : 1989 Guide to electrical earth monitoring and protective conductor proving

BS 5345 : - Code of Practice for selection, installation and maintenance of electricalapparatus for use in potentially explosive atmosphere (other than miningapplications or explosive processing and manufacture)

BS 6500 : 2000 Specification for electric cables Flexible cords rated up to 300/500 V, foruse with appliances and equipment intended for domestic, office and similarenvironments

BS 6708 : 1998 Flexible cables for use at mines and quarries

BS 7375 : 1996 Code of practice for distribution of electricity on construction and buildingsites

BS EN 60898 : 1991 Specification for circuit breakers for overcurrent protection for household andsimilar installations

IEC 60245-1 : 1994 Rubber insulated cables Rated voltages up to and including 450/750VPart 1 General requirements

IEC 60309-2 : 1999 Plugs, socket outlets and couplers for industrial purposesPart 2 Dimensional interchangeability requirements for pin and contact-tubeaccessories

SS CP 5 : 1998 Code of Practice for Electrical Installations

SS CP 16 : 1991 Code of practice for Earthing

SS CP 31 : 1996 Code of practice for Installation, operation, maintenance, performance andconstructional requirements of mains failure standby generating systems

SS CP 33 : 1996 Code of practice for lightning protection

SS 97 : Part 1 : 2000 Specification for Residual Current Circuit Breakers without IntegralOvercurrent Protection for Household and Similar Uses (RCCBs)Part 1 General rules

SS 145 : Part 1 : 1997 Specification for 13A plugs and socket outletsPart 1 Rewirable and non-wirable 13A fused plugs

SS 145 : Part 2 : 1997 Specification for 13A plugs and socket outletsPart 2 13A switched and unswitched socket-outlets

SS 358 : Part 5 : 1998 Specification for Polyvinyl chloride insulated cables of rated voltages up toand including 450/750VPart 5 Flexible cords


CP 88 : Part 1 : 2001

39

SS 359 : 1996 Specification for Circuit breakers for overcurrent protection for household andsimilar installations

SS 443 : Part 1 : 1998 Specification for Power cables with extruded insulation and their accessoriesfor rated voltages from 1 kV (Um=1.2 kV) up to 30 kV (Um = 36 kV)Part 1 Cables for rated voltages of 1 kV (Um = 1.2 kV) and 3 kV (Um = 3.6kV)

SS IEC 60529 : 1989 Specification for Degrees of protection provided by enclosures (IP Code)


CP 88 : Part 1 : 2001

40 COPYRIGHT

ABOUT SPRING SINGAPORE SPRING Singapore is an agency under the Ministry of Trade and Industry responsible for helping Singapore enterprises grow and building trust in Singapore products and services. As the national standards and accreditation body, SPRING develops and promotes an internationally-recognised standards and quality assurance infrastructure. SPRING also oversees the safety of general consumer goods in Singapore. As the enterprise development agency, SPRING works with partners to help enterprises in financing, capability and management development, technology and innovation, and access to markets. SPRING Singapore 1 Fusionopolis Walk #01-02 South Tower, Solaris Singapore 138628 Tel: 6278 6666 Fax: 6278 6667 E-mail: [email protected] Website: http://www.spring.gov.sg

ABOUT THE NATIONAL STANDARDISATION PROGRAMME Under the national standardisation programme, SPRING Singapore helps companies and industry to meet international standards and conformity requirements by creating awareness of the importance of standardisation to enhance competitiveness and improve productivity, co-ordinating the development and use of Singapore Standards and setting up an information infrastructure to educate companies and industry on the latest developments. SPRING Singapore is vested with the authority to appoint a Standards Council to advise on the preparation, publication and promulgation of Singapore Standards and Technical References and their implementation. Singapore Standards are in the form of specifications for materials and products, codes of practice, methods of test, nomenclature, services, etc. The respective committee or working group will draw up the standards before seeking final approval from the Standards Council or the relevant Standards Committee. To ensure adequate representation of all viewpoints in the preparation of Singapore Standards, all committees appointed consist of representatives from various interest groups which include government agencies, professional bodies, tertiary institutions and consumer, trade and manufacturing organisations. Technical References are transition documents developed to help meet urgent industry demand for specifications or requirements on a particular product, process or service in an area where there is an absence of reference standards. Unlike Singapore Standards, they are issued for comments over a period of two years before assessment on their suitability for approval as Singapore Standards. All comments are considered when a technical reference is reviewed at the end of two years to determine the feasibility of its transition to a Singapore Standard. Technical References can therefore become Singapore Standards after two years, continue as Technical References for further comments or be withdrawn. In the international arena, SPRING Singapore represents Singapore in the International Organisation of Standardisation (ISO), the Asia-Pacific Economic Co-operation (APEC) Sub-committee for Standards and Conformance (SCSC) and in the ASEAN Consultative Committee on Standards and Quality (ACCSQ). The Singapore National Committee of the International Electrotechnical Commission which is supported by SPRING Singapore, represents Singapore in the IEC.


The Singapore Standardisation Programme is managed by

SPRING Singapore 1 Fusionopolis Walk, #01-02 South Tower, Solaris Singapore 138628

Tel : +65 6278 6666 Fax : +65 6278 6667 www.spring.gov.sg


ContentsForeword1 General1.1 Scope1.2 Object1.3 Relationship with statutory regulations1.4 Use of established materials, equipment and methods1.5 New materials and inventions

2 Definitions3 General requirements3.1 Source of supply3.1.1 General3.1.2 Types of supply3.1.3 No parallel operation of generating set and the public electricity supply system3.1.4 Supply for equipment

3.2 Type of earthing arrangement3.3 Installation of generating set3.3.1 General3.3.2 Earthing arrangements of generating set3.3.3 Protection against direct contact of live parts3.3.4 Labelling on generating set

4 Protection for safety4.1 Control of supply4.1.1 General4.1.2 Protective device for incoming supply4.1.3 Protection of circuits4.1.4 Prohibited use of fuses for final circuits

4.2 Protection against direct contact4.3 Protection against indirect contact for low voltage system4.3.1 General4.3.2 Protection by residual current device4.3.3 Protection by residual current device for final circuits4.3.4 Earth leakage protection for transportable electrical equipment4.3.5 Protective conductor proving and earth monitoring systems

4.4 Protection against indirect contact for reduced voltage system4.5 Protection against lightning

5 Selection and erection of equipment5.1 General5.2 Wiring systems5.3 Switchgear and controlgear5.3.1 Enclosure for low-voltage assembly5.3.2 Switchboard and distribution board

5.4 Socket-outlets assembly5.5 Plugs, socket-outlets and cable couplers5.6 Cable for SOA Connection5.7 Earthing arrangement and protective conductor5.7.1 Protective earthing of metalwork5.7.2 Earthing of portable appliances and tools5.7.3 Earthing of metal sheath and armour of cables5.7.4 Metal sheath and/or armour of flexible or trailing cables5.7.5 Earthing of metal enclosure for switchboards and distribution boards

5.8 Other equipment5.8.1 Light fixtures5.8.2 Portable hand-lamps5.8.3 Prohibited use of lampholders fitted with pin contacts5.8.4 Electrical welding system

5.9 Equipment for reduced voltage system5.9.1 Plug, socket-outlet and cable coupler of a reduced voltage system5.9.2 Switches for reduced voltage circuits

6 Inspection, testing and maintenanceAnnex A Statutory regulations and associated memorandaAnnex B Protective conductor proving and earth monitoring systemsAnnex C Temporary electrical installations inspection checklist fo

cp 88 code of practice for temporary electrical installations

Documents