GENERAL SPECIFICATION - Architectural Services Department

1 GENERAL SPECIFICATION FOR ELECTRICAL INSTALLATION IN GOVERNMENT BUILDINGS OF THE HONG KONG SPECIAL ADMINISTRATIVE REGION 2002 EDITION THE HONG KONG SPECIAL ADMINISTRATIVE REGION BUILDING Services BRANCH Architectural Services Department COPYRIGHT This GENERAL SPECIFICATION is solely compiled for use on electrical installations in Government buildings of the Hong Kong Special Administrative Region. 2. This GENERAL SPECIFICATION for Electrical Installation is copyrighted and all rights (including subsequent amendments) are reserved. 3. It is hereby declared that the SPECIFICATION contained herein may not be pertinent or fully cover the extent of installations carried out by others. Prior consent by the Director of Architectural Services must be obtained for adoption of this GENERAL SPECIFICATION on installations of other nature or locations.

2 Table of Contents Page 1 of 23 TABLE OF CONTENTS PART A : SCOPE AND GENERAL REQUIREMENTS SECTION A1 : SCOPE OF SPECIFICATION Installation to Comply with this SPECIFICATION Installation to Comply with the Particular SPECIFICATION and Drawings Voltage Covered by this SPECIFICATION Definitions, Interpretation and Abbreviations Singular and Plural SECTION A2 : STATUTORY OBLIGATIONS AND OTHER REGULATIONS Installation to Comply with Obligations and Regulations Safety Requirements Case of Conflict SECTION A3 : GENERAL REQUIREMENTS ON MATERIAL, EQUIPMENT, WORKMANSHIP AND QUALITY Material and Equipment International Standards Other Standard Specifications The International System of Units (SI) Service Conditions Selection of Equipment Equipment Catalogue and Manufacturer s SPECIFICATION Workmanship Tradesmen Tool and Instrument Safety on Site Label and Notice Inscription of Label and Engraving Material for Label Fixing of Label Engraving for Electrical Accessory Warning Notice Other Labels and Notices Guard and Railing for Moving or Rotating Parts of Equipment Insulating Material Identification of Cable and Conduit Minimum Size of Cable Conductor Table of Contents Page 2 of 23 Use of PVC-insulated Cable at Low Temperature Fixing Screw and Bolt Fixing to Wooden Plug Sheet Metal Work Painting of Metal Work Water Proofing Main and Sub-main Switch Room and Electrical Riser Duct/Room Free From Water Service SECTION A4.

3 OTHER GENERAL REQUIREMENTS Scope of Requirement Standard/Guidance Drawings Drawings provided by the Contractor Size of Drawing Working Drawing As-fitted or As-built Drawing Submission of Drawings during Construction Submission of Framed Drawings upon Completion Submission of Technical Information during Tender Stage Submission of Operation and Maintenance (O&M) Manuals Samples Board Submission of Testing and Commissioning Procedure Domestic Appliances Supplied by the Employer Provision of Spare Fuses in Main Switch Room Requirements during Maintenance Period PART B : INSTALLATION METHODOLOGY SECTION B1 : INSTALLATION OF WIRING SYSTEMS Wiring in Steel Conduit System Type of Cable Concealed Steel Conduit System Surface Conduit System Minimum Size of Conduit Flexible Conduit Conduit Continuity Joint in Conduits Provision of Adaptable Box Spacing between Conduits Termination of Conduits at Metal Casing of Equipment Conduit Bend Conduit Crossing Expansion Joint Use of Extension Ring Prevention of Ingress of Foreign Matters Prevention of Accumulation of Water or Moisture Conduit Laid Direct in Ground Fixing of Distance (Spacing)

4 Saddle Table of Contents Page 3 of 23 Conduit Installed Outdoors or in Damp Situation Swabbing Out of Conduit Fire Barrier Identification Cable Capacity of Conduit Method of Drawing Cables into Conduit Segregation of Cables of Different Circuit Categories Looping-In Wiring System Grouping of Cables in Conduit Termination of Bonding Conductors at Conduit Installation Wiring in Steel Trunking System GENERAL Provision of Cable Retaining Bar and Cable Support Cable Capacity of Trunking Correction Factor of Grouping Segregation of Cables of Different Circuit Categories Connection to Equipment Connection to Distribution Board Fixing of Surface Trunking Cables through Trunking Fire Barrier Prevention of Electrolytic Action Prevention of Ingress of Water Wiring in Plastic Conduit or Plastic Trunking System GENERAL Pliable Conduit Joint in PVC Conduit Plastic Boxes Termination of PVC Conduit at Casing of Equipment Conduit Bend Allowance for Thermal Expansion Fixing of Trunking Earthing Surface Wiring System Type of Cable Minimum Size of Live Conductors and CPC Identification of Cable Core Joint in Cable or Cord Installation of Non-flexible Cable Installation of Flexible Cable and Flexible Cord Table of Contents Page 4 of 23 Tool and Workmanship Approved Tool Cutting in Metal Work for Conduit or in Trunking Making Good of Damaged Coating SECTION B2.

5 INSTALLATION OF POWER CABLES, CABLE TRAYS AND CABLE LADDERS GENERAL Scope Electromagnetic Interference Cable Mounted on Surface Cable Laid in Enclosed Trench Cable Enclosed in Duct GENERAL Drawing-in of Cables Internal Barrier Fire Barrier Draw-in Pit Segregation of Cables of Different Circuit Categories Sealing of Duct Entry to Building Cable Buried Direct in Ground Protection of Cable Cable Marker Bending Radius of Cable Cable Joint and Cable Termination GENERAL Joint Box and Termination Box Identification at Joint or Termination Earth Continuity across Joint Straight-through Joint for Copper Conductors Tee-joint for Copper Conductor Joint for Aluminum Cables Termination of PVC-insulated or XLPE-insulated Cable with Copper Conductors Termination of PVC-insulated or

6 XLPE-insulated Cable with Aluminum Conductors Use of Heat Shrinkable Tubing Other Methods of Joint and Termination Table of Contents Page 5 of 23 Special Requirements for Mineral Insulated Cables Cable Route Cable Support Bending Radius Cable Loop for Prevention of Vibration and Low Temperature Cold Store Cable Termination Insulation Resistance Bonding of Cable Sheath to Metalwork Laying of Single-core Cables Protection from Mechanical Damage Installation of Cable Trays Connection between Adjacent Lengths of Tray Cutting of Tray Hole in Tray Fixing of Tray Fixing of Cable on Tray Installation of Cable Ladder Dropout Plate for Cable Exit Flexible (Expansion) Couplers across Building Expansion Joint Ladder Covers End Connectors Earthing Minimum Inside Radius of All Bends Supports Spare Capacity Safety Working Load SECTION B3.

7 INSTALLATION OF GENERAL LIGHTING AND POWER Installation of Lighting System and Luminaires Pendant Luminaire Mounted on Pattress Ceiling Rose Cable in Enclosed Luminaire Stroboscopic Effect Painting Special Requirements for Outdoor Luminaires Installation of Wiring Accessories Table of Contents Page 6 of 23 Installation of Domestic Switches GENERAL Lighting Switch Time Switch Application in Bathroom Installation of Socket Outlets GENERAL Shaver Supply Unit Socket Outlet at Hazardous Area Socket Outlet on Surface Conduit System Socket Outlet for Different Voltage System Application in Bathroom Installation of Measuring Instrument Mounting of Current Transformers Associated with Watt-hour Meter Identification of Instrument Mounting Position of Selector Switch SECTION B4 : INSTALLATION OF DOMESTIC APPLIANCES GENERAL Connection to Appliances Use in Bathroom and Toilet Engraving for Identification Earthing of Appliance Appliance Requiring Exclusive Circuit Ceiling Fan and Ceiling-mounted Rotary Fan Method of Supply Fixing of Fan Fan Regulator Wall-mounted Fan Exhaust Fan Fixing of Fan Method of Supply Electric Fire or Heater Wall-mounted Radiator Panel Fire Tubular Heater Table of Contents Page 7 of 23 Water Heater and Water Boiler Oversink Water Heater Other Type of Water Heater Water Boiler Tea Urn Household Electric Cooker Hand/Face Dryer Room Cooler Method of Supply Position of Terminal Block Refrigerator SECTION B5.

8 INSTALLATION OF BUSBAR TRUNKING SYSTEM GENERAL Site Storage and Protection Busbar Identification Joint in Busbar Expansion Unit Feeder Unit Tap-off Unit Connection Fire Barrier Busbar Trunking Accessories Support of Busbar Trunking System Earthing Requirements for Air-insulated Busbar Trunking System Application Busbar Supports Tap-off Fire Barrier Mounting Brackets Requirement for All Insulated Busbar Trunking System Application Busbar Jointing Expansion Unit Tap-off Unit Supporting Hangers and Fixing Brackets Table of Contents Page 8 of 23 SECTION B6 : INSTALLATION OF EARTHING SYSTEM GENERAL Main Earthing Terminal Earth Electrode Types of Earth Electrode Rod Electrode Tape Electrode Plate Electrode Electrode in Deep Bored Hole Connection between Electrodes Earthing Conductor Conductor Material Connection to Electrodes Main Equipotential Bonding Conductor Conductor Material Bonding Position Bonding Method Supplementary Bonding Conductor Conductor Material Application in Bathroom Application in Other Areas Bonding Method Circuit Protective Conductor (CPC)

9 GENERAL CPC for Socket Outlet CPC for Flexible Conduit CPC for Busbar Trunking and Busway CPC for Ring Final Circuit Joints in Protective Conductors Identification and Labelling Colour Identification Label for Earthing and Bonding Connections Sizing of Protective Conductor GENERAL Equipotential Bonding Conductor Table of Contents Page 9 of 23 Earth Fault Loop Impedance Automatic Disconnection Time Maximum Earth Loop Impedance Condition for Compliance Use of Residual Current-operated Circuit Breaker GENERAL Application in Household Installation Equipment Outside an Equipotential Zone SECTION B7 : MISCELLANEOUS INSTALLATIONS Telecommunication Systems Scope Conduit for Telephone, Computer Network, Inter-communication and PA Systems Outlet Box for Telephone Point Outlet Box for Computer Point Outlet Box for Inter-communication and PA System Conduit for Staff Paging System Conduit for Broadcast Reception System Outlet Box for Broadcast Reception System Bell and Audible Warning System Class-change Bell System for Schools Bell for Mains Voltage Call Bell and Door Bell Systems Bell and Buzzer for Extra Low Voltage Bell Transformer Call Bell Push Mounting of Call Bell Push Table-type Push Table-type Push in Concealed Conduit Installation Bell Indicator Segregation of Circuits Fire Service Installation Scope Conduit and Trunking Systems Use of Flame Retarding Cables Table of Contents Page 10 of 23 Installation in Hazardous Areas GENERAL

10 Electrical Equipment Selection Wiring System Conduit Fitting, Cable Glands, Terminal Box and Enclosure Screw or Bolt Luminaire Conduit Pendant Cables or Conduits Passing through Floor, Wall or Partition Precautions to Prevent Passage of Inflammables Gases or Vapours Equipotential Bonding of Conduit External Lighting System Scope SPECIFICATION and Drawing Luminaire Construction of Lamp Pole Foundation of Lamp Pole Service Box Underground Cable to Pole Cable between Service Box and Luminaire Switch Fitted to Pole Control Gear for Discharge Lighting Testing of Illumination Level Numbering of Lamp Pole Lightning Protection System Installation of Lightning Protection System Scope Type of Lightning Protection System Air Termination Down Conductor Test Joint Earth Termination Spacer Saddle Connection to Earth Termination Bonding to Other Services Bond Joint in Conductors Testing Table of Contents Page 11 of 23 PART C.