Electrical Installations in Buildings - APSR

1 sultanate OF oman STANDARD OES-4 Electrical Installations in Buildings Third Edition November 2021 Page 2 of 108 INTRODUCTION This third edition of the REGULATIONS FOR Electrical Installations in the sultanate OF oman , takes into account, as far as possible, the latest practices and installation methods meeting the approval of the Authority for Electricity Regulation, oman . It is essential that all contractors and wiremen study and abide by the Regulations as laid down in this publication, and in particular the section on safety. The Regulations contained herein come into effect on 1st January 2020. NOTE: Some of the material in the Requirements for Electrical Installations BS 7671 (formerly IEE Wiring Regulations), IEC, Kuwait Bahrain, Abu Dhabi standards has been adapted as appropriate and applicable to the sultanate .

2 This is hereby acknowledged. Page 3 of 108 Contents 1 GENERAL .. 10 SCOPE .. 10 COMPLIANCE WITH REGULATIONS .. 10 PRECEDENCE .. 10 Electrical DESIGN .. 11 DOCUMENTATION AND SUBMISSION OF DESIGN .. 11 INSTALLATION WORK .. 11 INSPECTION .. 11 DEFINITIONS .. 11 2 FUNDAMENTAL PRINCIPLES .. 19 REQUIREMENTS FOR SAFETY .. 19 BASIC PROTECTION AGAINST DIRECT CONTACT .. 20 FAULT PROTECTION AGAINST INDIRECT CONTACT .. 20 PROTECTION AGAINST THERMAL EFFECTS FROM NORMAL OPERATION, OVERCURRENT AND EARTH FAULT CURRENT .. 20 PROTECTION AGAINST ABNORMAL VOLTAGES .. 21 DESIGN AND SUITABILITY OF EQUIPMENT .. 21 CONDUCTOR SIZE .. 22 PROTECTIVE EQUIPMENT.

3 22 OVERLOAD PROTECTION .. 23 SHORT-CIRCUIT PROTECTION .. 23 DIVISION, ISOLATION AND RELIABILITY OF THE Installations .. 23 PROTECTION COORDINATION, DISCRIMINATION AND BACK-UP .. 24 EQUIPMENT LAYOUT .. 24 IDENTIFICATION OF CONDUCTORS .. 24 CONNECTIONS AND TERMINATIONS .. 24 EARTH BONDING .. 24 TESTS ON 25 3 GENERAL REQUIREMENTS .. 25 SITE CONDITIONS .. 25 CHARACTERISTICS OF MAINS SUPPLY .. 25 VOLTAGE 26 IDENTIFICATION, LABELLING AND SIGNAGE .. 26 Page 4 of 108 4 EQUIPMENT 27 CONDUCTORS AND CABLES .. 27 NONFLEXIBLE CABLES .. 27 FLEXIBLE CABLES AND 27 UNDERGROUND CABLES .. 27 OVERHEAD LINE CONDUCTORS .. 27 LOW VOLTAGE SWITCHGEAR AND CONTROL GEAR.

4 28 ARC FAULT PROTECTION .. 28 AIR BREAK SWITCHES AND FUSE SWITCHES .. 28 CIRCUIT BREAKERS .. 29 FUSE BOARDS .. 29 MINIATURE CIRCUIT-BREAKER BOARDS .. 29 MINIATURE CIRCUIT-BREAKERS .. 29 CONSUMER UNITS .. 29 USE OF RCDS .. 29 SWITCHES FOR USE IN WIRING Installations .. 30 PLUGS AND SOCKET-OUTLETS .. 30 LIGHTING EQUIPMENT, LUMINAIRES AND ACCESSORIES .. 30 LUMINAIRES .. 30 LED LIGHTING .. 30 CEILING ROSES .. 30 LAMP HOLDERS AND STARTER HOLDERS .. 30 DISCHARGE LAMPS .. 30 STREET FURNITURE AND STREET LOCATED EQUIPMENT .. 31 COOKER CONTROL UNIT .. 31 ELECTRIC SHAVER SUPPLY UNIT .. 31 PVC CONDUITS AND FITTINGS .. 31 STEEL CONDUITS AND FITTINGS.

5 31 BOXES FOR ACCESSORIES .. 31 AIR CONDITIONING EQUIPMENT .. 31 5 SERVICE CONNECTION AND CONSUMER'S INSTALLATION .. 32 GENERAL .. 32 MAIN SWITCHBOARD GENERAL ARRANGEMENT AND LOCATION .. 32 SERVICE CONNECTION FOR LOAD NOT EXCEEDING 400 KVA .. 32 Page 5 of 108 SERVICE CONNECTION FOR LOAD EXCEEDING 400 KVA .. 33 SERVICE CONNECTION TO DETACHED Buildings .. 33 LOAD BALANCING .. 33 CONSUMER'S INSTALLATION .. 33 CONTROL OF INCOMING SUPPLY .. 33 MEANS OF ISOLATION .. 34 OVERCURRENT PROTECTION .. 34 EARTH LEAKAGE PROTECTION .. 34 SEQUENCE OF PROTECTIVE DEVICES: SINGLE CONSUMER INSTALLATION 34 SEQUENCE OF PROTECTIVE DEVICES: MULTI-CONSUMER INSTALLATION .. 35 LOCATION OF SWITCH AND CONTROL GEAR.

6 37 SEGREGATION OF SUPPLY AND CONSUMER'S CABLES .. 37 CONSUMER'S EARTHING SYSTEM .. 37 CONNECTION OF SWITCH AND CONTROL GEAR .. 38 PROTECTION OF INDIVIDUAL CIRCUITS .. 38 SEGREGATION OF PHASE CIRCUITS .. 38 CONNECTION OF NEUTRAL CONDUCTORS IN DISTRIBUTION BOARDS .. 39 COOKING APPLIANCES .. 39 CONTROL OF WATER HEATERS .. 39 CONTROL OF AIR CONDITIONING UNIT /PLANT .. 39 LOAD ON LIGHTING CIRCUITS .. 39 SOCKET-OUTLETS IN DOMESTIC AND COMMERCIAL Installations .. 39 SOCKET-OUTLETS IN INDUSTRIAL AND OTHER NON-DOMESTIC Installations .. 40 LIGHTING SWITCHES .. 40 MAIN CABLE ENTRY .. 40 MAINS SUPPLY FOR MOTORS .. 41 CONTROL AND PROTECTION FOR MOTORS .. 41 6 INSTALLATION OF CONDUCTORS AND CABLES.

7 42 PERMISSIBLE VOLTAGE DROP .. 42 CURRENT RATINGS .. 42 PARALLEL OPERATION .. 42 PROTECTION AGAINST DAMAGE .. 42 METHODS OF INSTALLATION .. 42 CABLES FOR LIFT .. 43 Page 6 of 108 CABLE SUPPORTS .. 43 RADIUS OF BEND .. 43 CABLE TERMINATIONS .. 43 JOINTS .. 44 PROTECTION AGAINST FIRE .. 44 EARTH-CONTINUITY CONDUCTOR .. 44 DISTRIBUTION SYSTEM IN MULTI-STOREY Buildings OR AREAS WHERE A PARTICULAR RISK OF FIRE EXISTS .. 44 CONSUMER'S UNDERGROUND WIRING .. 45 CONSUMER'S OVERHEAD WIRING .. 45 CABLES IN STEEL CONDUITS, TRUNKING OR 45 SEGREGATION OF LOW VOLTAGE AND EXTRA-LOW VOLTAGE CIRCUITS .. 45 FLEXIBLE CORDS AND CABLES .. 46 COLOUR IDENTIFICATION OF CABLE CORES.

8 48 7 INSTALLATION OF CONDUITS, TRUNKING AND TRAYS .. 49 INSTALLATION OF CONDUITS .. 49 CONDUIT SUPPORTS .. 49 SMOOTH FINISH OF CONDUITS .. 49 RADIUS OF BENDS .. 49 GALVANISED STEEL CONDUITS .. 49 PVC CONDUITS AND FITTINGS .. 50 FLEXIBLE CONDUITS .. 50 CONDUIT SIZES .. 50 CABLE TRUNKING .. 50 CABLE TRAYS .. 51 8 EARTHING AND EARTH LEAKAGE PROTECTION .. 51 CONSUMER'S EARTHING INSTALLATION .. 51 EARTH-CONTINUITY CONDUCTOR .. 51 EARTHING TERMINAL OF SOCKET-OUTLETS .. 51 EARTHING TERMINAL OF LIGHTING POINTS .. 51 RESISTANCE OF EARTH-CONTINUITY CONDUCTOR .. 51 BONDING OF METAL WORK .. 51 NEUTRAL CONDUCTOR .. 52 ADDITIONAL PROTECTION BY RCDS .. 52 LOCATION OF RCDS.

9 53 Page 7 of 108 9 INSTALLATION OF ACCESSORIES AND APPARATUS .. 53 VOLTAGE RATING .. 53 CURRENT RATING .. 53 TERMINAL MARKINGS AND EARTH MONITORING .. 53 LIGHTING SWITCHES .. 54 CEILING ROSES .. 54 LAMP HOLDERS .. 54 PENDANT LIGHTING .. 54 MOUNTING HEIGHTS OF ACCESSORIES .. 55 PROTECTION OF CONSUMER'S SUB-CIRCUITS .. 55 EXTRA-LOW VOLTAGE APPARATUS .. 55 ACCESSORY BOXES .. 55 AUTO-TRANSFORMER IN CONSUMER'S INSTALLATION .. 55 WATER HEATER .. 56 UNDER WATER LIGHTING .. 56 ELEVATORS AND ESCALATORS .. 56 STAND-BY GENERATORS .. 56 FESTOON LIGHTING .. 57 LIGHTNING AND OVERVOLTAGE PROTECTION .. 57 10 Installations ON CONSTRUCTION AND BUILDING SITES.

10 58 GENERAL .. 58 Electrical APPARATUS AND CABLING .. 58 DISTRIBUTION UNITS .. 58 PORTABLE APPARATUS AND SITE LIGHTING .. 58 SOCKET-OUTLETS .. 58 110 V PLUGS AND SOCKETS .. 59 COLOUR CODE FOR ACCESSORIES .. 59 REDUCED VOLTAGE SYSTEM .. 59 CABLES .. 59 LAMP HOLDERS .. 59 MAINTENANCE AND INSPECTION .. 60 11 AGRICULTURAL AND HORTICULTURAL Installations .. 60 GENERAL .. 60 LOCATION OF SWITCHGEAR .. 60 Page 8 of 108 ISOLATION AND CONTROL .. 60 PROTECTION OF CABLES .. 60 INSTALLATION OF CABLES .. 60 PROTECTION OF EARTHING LEAD .. 61 EXTRA-LOW VOLTAGE (ELV) .. 61 12 SPECIAL Installations OR LOCATIONS .. 61 DAMP AND WET AREAS .. 61 GENERAL .. 61 TEMPORARY INSTALLATION-INCLUDING SITE SUPPLY.