The electrical work for the new bidding document of the apartment or building, we need to mention about the general like as preamble, unit, standards, materials, installation, document, sample…etc after that we go through the service of scope of work with including main electrical supply, generator electrical supply, distribution system supply, lighting and general power, telephone and communications cabling…etc. All the above we also show about the materials are using in this electrical works like as cable, conduit pipe, power outlet, switchboard, circuit breaker, lighting fixture… etc.

All above we can know well for proposal electrical specification as below:

1. General

 1.1     Preamble;

The requirement for electrical services under the scope of works call for a reliable and Safe electrical system consistent with a recognized international standard.

The electrical service shall be an earthed system using methodology and or standards using either direct or M.E.N earthling systems

The system shall comprise current materials, work practices and safety standards.

The specification below shall be read in conjunction with plans drawings and electrical standard and is intended to serve as a guide. A Standard of Electrical wiring will detail most aspects of the electrical installation and where not cleat the below will serve as the primary reference.

The electrical service is made up of the following components:

Main Electrical Supply

  • Generator Electrical Supply
  • Distribution System
  • Lighting and general Power
  • Telephone and communication cabling

1.2     Units;

The system proposed shall use Metric Units for sizing, measurement and labeling

1.3         Standards;

           Standards adopted shall have a system based and an electrical supply system having

Voltage of 220-240 V Single Phase, 380 – 415V three phase and frequency of 50 Hz.

Applicable compliant Standards are:

  • British Standard
  • Singapore
  • Malaysian
  • Australia
  • New Zealand

Where one of the above systems or alternative standards are proposed, all materials shall have been tested for compliance with the standard.

The electrical system shall be a system where the materials and methodology are based on the same method of testing and design.

Where standards overlap or testing procedures for materials and methodology are internationally compliant, the highest standard shall apply.

Where materials are rated differently in accordance with standards for installation all capacities shall be de-rated in order to provide the maximum safety levels.

1.4      Materials;

Materials used shall be new and free of defects.

All materials used shall be proven compliant with the installation standard adopted.

The onus is on the contractor to submit samples and documentation on materials

Proposed prior to contract acceptance.

Materials shall be clearly marked as to the standards complied with.

Materials shall be clearly manufactured by ISO certified companies.

1.5     Installation;

Installation shall comply in its entirety with the standard proposed and shall be consistent

Throughout the installation.

The installation standard shall be used as a base for comparative evaluation as to the

Compliance of bids.

Both materials and installation method shall be fully compliant with each other and shall

Result in an installation fully compliant with the standard proposed.

The contractor shall provide the client with copies of all documentation including copies of

Standards.

1.6     Documentation;

  •  Switch Gear
  • Switchboards
  • Circuit Breakers
  • Cables, connectors and terminators
  • Conduits and  Pipe
  • Light fixtures
  • Power and special purpose outlets
  • Switches
  • Wall mounting and junction boxes
  • Standard

1.7       Samples;

Materials samples shall be provided for the following Items;

  •  Cables, connectors and terminators
  •  Conduits and Pipe
  • Light fixtures
  • Power and special purpose outlets
  • Switches
  • Wall mounting and junction boxes
  • Standards

2.        Services

2.1      Main Electrical supply

The main electrical supply will be provided from the municipal electrical service.

The main supply will be rated at? Amperes and shall be terminated at the main switch located in the main switch room.

The scope of works applies to all electrical connections from the main termination point switch.

The contractor shall not modify or make alteration to any part of the main service and shall be fully responsible for any actions arising from any such alterations or modifications.

The contractor shall supply a main cable and connect from the load side of the main switch to and isolation switch located at the generator transfer switch.

2.2    Generator Electrical Supply

A generator electrical supply cable of? Capacity shall be connected to the generator at the generator isolation switch and terminated at the main switch of the main switchboard.

2.3     Distribution System Supply

A distribution supply cable or? Capacity shall be installed connected to the load side of the Generator changeovers switch and terminated at the main switch of the switchboard.

2.4     Lighting and General Power

 A network of sub-main and sub-circuit cabling shall be installed as indicated on drawing. Cable shall include all cables to and from distribution boards as indicated on drawings inclusive of all accessories required to facilitate works under the standard proposed.

2.5     Telephone and Communication Cabling

A network of communication cabling shall be installed as indicated on drawings and shall be compliant with the standards of installation proposed. Communications cabling shall include all telephone, data and computer cabling.

3.        Materials

3.1        Cables 

All Cables shall comply with the below general specification. Where variance for the specification is found in accordance with the standard proposed, Items shall be detailed for review. Any variance from the specification shall be noted and tabled prior to use to purchase. Items not complying May be rejected.

All electrical cable shall have an insulation rating of not less than 0.6/1KV at 50 Hz AC.

Cables shall a thermal rating of not less than V70

All cables shall use stranded copper conductors.

All cables shall have earth conductors within the cable sheath except where used for switching of main supply cables.

Flexible cords shall not be used as fixed wiring.

Flexible cords shall be used only under the following conditions:

  • For connection to pendant or suspended lighting
  • For connection to a fixed appliance
  • Where terminations and designed for flexible cabling by having compression type fixings
  • Where wires are tinned prior to termination.

Switch wires shall be Red and White only. Other phase colors shall not be used for switching.

Cable colors used shall be either of the following configurations;

Joints in cables shall only be acceptable where:

  • A joint / splice is required due to extraordinary cable length
  • A change in direction to branch a cable
  • Within a fixture, only at the fixture terminal.

A joint if required under the above conditions the joint shall be:

  • Enclosed in an approved junction box
  • Use screw type connectors
  • Made using manufacturers approved jointing kit.

Cables shall be tested at their rated voltage prior to and upon completion of installation.

Cables damaged during installation shall be replaced

Cables damaged prior to installation shall not be used.

Cable Damage includes:

  • Cut or damaged insulation
  • Squashed, stretched or flattened cables
  • Kinked cables
  • Discolored cables
  • Cables having unsealed ends
  • Scraped insulation

3.2         Conduits & Pipe  

All conduits and pipe shall comply with the below general specification. Where variance for the specification is found in accordance with the standard proposed, items shall be detailed fro review. Any variance from the specification shall be noted and tabled prior to use or purchase. Items not complying may be ejected. Manufactures data on products proposed shall be supplied prior to purchase or ordering. Data shall detail compliance with standards proposed.

All electrical service pipe and conduits shall be manufactured for electrical use.

Water pipe, telecommunication ducts and the like shall not be used for any electrical service carrying conductors at a voltage in excess of 36 Volt.

All fittings used shall be fully enclosed and sealed using manufacturers recommended sealing compounds and or adhesives.

Surface mounted conduits installed indoors in a horizontal configuration shall be metallic.

Metal conduits shall be mechanically bonded to the earthling conductors.

Metal conduits shall have PVC bushes fitted where any part of the conduit extends into a fitting or fixture.

All other conduits used shall be heavy duty UPVC

All conduits shall be bent only using manufacturers specified bending equipment and devices.

Conduits distorted or flattened during bending shall not be used.

Flexible conduits shall be heavy duty type and be fitted with manufacturers terminations only.

Conduit entries into fittings and fixtures shall be cut to length and cleaned of burrs or any sharp edges.

3.3         Power & Special Purpose Outlets

All Outlets and plates shall comply with the below general specification. Where variance for the specification is found in accordance with the standard proposed, items shall detailed for review. Any variance from the specification shall be noted and tabled prior to use or purchase. Items not complying may be rejected.Non-genuine items will be rejected

All general purpose power outlets shall be Clipsal Brand E38 Pattern.

All outlets shall be genuine and shall not be substituted for alternate brands.

All outlets shall be double configuration

All outlets shall be electric white in colour.

All outlets shall be new and installed in new condition.

Outlets damaged, scratched or having been painted shall be replaced.

Weatherproof outlets shall be E38 pattern and shall be a minimum of IP 56 rated.

Weatherproof outlets shall be single configuration.

Special purpose outlets shall be E38 Pattern unless otherwise specified.

Special purpose outlets shall be single configuration.

 3.4         Switchboards

All Switchboards shall comply with the below general specification. where variance for the specification is found in accordance with the standard proposed, items shall be detailed for review. Any variance from the specification shall be noted and tabled prior to use or purchase. Items not complying may be rejected. The contractor is to furnish the client with manufacturer’s specification data prior to purchase or order.

Main Switchboards shall have the following specification;

  • Metallic Enclosure
  • Have a duty rating for commercial application
  • Manufactured by a recognized switchboard manufacturer.
  • Polyester Powder Coated
  • Factory painted grey or light brown
  • Have a Type tested bus bar system
  • Have a color coded insulated bus bar system
  • Have an IP rating of at least IP54
  • Have separate earth bar
  • Have separate insulated neutral bar
  • Have capacity in each bar to accommodate all poles
  • Have  spare capacity of 30%
  • Have a metallic escuteon plate
  • Have pole fillers for any unused poles
  • Have a legend board fitted
  • Have lockable metallic door
  • Fitted with removable gland plates at cable entry points

Non-metallic switchboards may be acceptable were total load is less than 100A inclusive of spare capacity. Details and specifications shall be provided where substitutions from metallic switchboards are offered. Non-metallic switchboards shall be suitable and designated for use in commercial applications.

Sub-boards and distribution boards shall have the following specification where non- metallic enclosures are proposed.

  • Have a bus bar system of capacity of not greater than 100A
  • Have DIN rail mounting for circuit breakers
  • Have spare capacity of 20%
  • Have separate earth bar
  • Have separate insulated neutral bar
  • Have capacity in each bar  to accommodate all poles
  • Have pole fillers for any unused poles
  • Have a legend board fitted
  • Have lockable door

3.5         Circuit Breakers

All circuit-breakers shall comply with the below general specification. Where variance for

the specification is found in accordance with the standard proposed, items shall be detailed for review. Any variance from specification shall be noted and tabled prior to use or purchase. Items not complying may be rejected. The contractor is to furnish the client with manufacturer’s specification data prior to purchase or order.

All circuit breakers and arrangement of such shall comply with the below specification.

Main Circuit Breakers shall be

  • MCCB type
  • Have thermal, magnetic trip mechanisms
  • Have adjustable trip mechanism
  • Have a fault rating of 35KA unless otherwise determined by the EDC supply authority.
  • Fitted to the Main switchboard without alteration to either board or switch.
  • Have a current rating not exceeding that of the mains cable capacity.
  • Same type and brand as the switchboard manufacturer.

Circuit Breakers shall be

  • MCCB type
  • Have thermal, trip mechanisms
  • Have fixed mechanism
  • Have a fault rating of 10KA unless otherwise specified.
  • Fitted to the switchboard without alteration to either board or switch.
  • Have a current rating not exceeding that of the supplied cable capacity.
  • Same type and brand as the switchboard manufacturer.

Miniature Circuit breakers shall be;

  • Miniature type
  • Have thermal, trip mechanisms
  • Have fixed mechanism
  • Have a fault rating of 6KA unless otherwise specified.
  • Fitted to the switchboard without alteration to either board or switch.
  • Mounted to the switchboard via DIN rail Clip mounting.
  • Have a current rating not exceeding that of the supplied cable capacity.
  • Same type and brand as the switchboard manufacturer.

RCD Devices.

RCD Devices, (Residual Current Devices) otherwise known as Ground Fault Interrupters, Differential Interrupters or ELCB’s shall meet the following specification.

          RCD’S shall be;

  • MCCB type
  • Thermally rated as the MCCB
  • C Curve rated for general application
  • Have a fault rating of 10KA unless otherwise specified.
  • Rated at not more than 30ma for leakage trip
  • Fitted with test button
  • The same brand and type as MCCB’s

All circuit breakers shall be the same brand and type within a switch or distribution board. All Circuit breakers shall have a general service application rating of C Curve. All motor protection circuit breakers shall have a motor start rating. General Service circuit-breakers shall not be used for motor start circuit.

3.6     Switches

All switches and mechanisms shall comply with the below general specification. Where variance for the specification is found in accordance with the standard proposed, items shall be detailed for review. Any variance from the specification shall be noted and tabled prior to use or purchase. Items not complying may be rejected. The contractor is to furnish the client with manufacturer‘s specification data prior to purchase or order.

Switch plates and mechanisms shall meet the following requriement;

  • Electric White in colour
  • Rectangular in shape
  • The same mounting pattern as power outlets
  • Use the same mounting box as outlets
  • Have 10A switch mechanisms
  • Have 2 way switch mechanisms
  • Manufactured by Clipsal or other Client approved makes
  • Be genuine products
  • Have a maximum of 4 switch mechanisms per plate
  • Shall be installed in new condition
  • Damaged, scratched or painted units shall be replaced
  • Shall be installed level

Fluorescent light switches in addition to the above shall meet the below criteria

  •  Shall be designated for use with fluorescent lighting
  • Have designation clearly marked

3.7     Mounting and junction boxes

All mounting and junction boxes shall comply with the below general specification. Where variance for the specification is found in accordance with the standard proposed, items shall be detailed for review. Any variance from the specification shall be noted and tabled prior to use or purchase. Items not complying may be rejected. The contractor is furnish the client with manufacturer’s specification data prior to purchase or order. Attention to earthing and continuity is required where metallic and non-metallic components are used. Double insulation shall be maintained throughout the wiring system.

Wall & mounting boxes shall meet the following criteria.

  • Be either metallic or Heavy duty PVC
  • Metal boxes shall be hot dipped galvanized and be pre-punched for conduit entries
  • Metal boxes shall be fitted with concrete grips.
  • PVC boxes shall be fitted with molded concrete wall grips.
  • PVC boxes shall be heavy duty and have molded knock outs for conduit entry
  • Have level adjustment within the box in the form of adjustable sliding fixture nuts

PVC junction boxes

  • shall have molded conduit entries

All wall, mounting and junction boxes shall be free of sharp edges and burrs and shall be suitable for its intended application. All boxes in damp, wet or fitted external to the building shall be PVC and weatherproof as designated by the IP56 rating of the box.

3.8     Light Fixtures

All light fixtures shall comply with the below general specification. Where variance for the specification is found in accordance with the standard proposed, items shall be detailed for review. Any variance from the specification shall be noted and tabled prior to use or purchase. Items not complying may be rejected. The contractor is to furnish the client with manufacturer’s specification data prior to purchase or order. Attention to earthing and continuity is required where metallic and non-metallic components are used. Double insulation shall be maintained throughout the wiring system and into the fixture.

Light fittings shall meet the below specification.

Fluorescent lighting fixtures.

  • Shall be polyester powder coated
  • White in color
  • Be fitted with white reflectors
  • Power factor corrected to 0.8
  • Use only 80 series tri- phosphor lamps
  • Be fitted with externally serviceable starter
  • Have high temperature wiring
  • Be fitted with tunnel type connection strip
  • Have earth terminal fitted

Other lighting fixtures

  • Shall be suitable for intended application
  • Shall be commercial duty
  • Shall be heavy duty where installed outdoors or exposed to UV
  • Shall be weatherproof where installed outdoors and having potential exposure to weather.
  • All metallic fixtures shall be earthed by bonding to the main earthing conductor.