Electrical engineering specification
Essential elements
Introduction 3
General lighting/luminaries and lamps 3
General LV power 3
Emergency lighting 4
Fire detection and alarm 4
Central control/building management 4
LV switchgear and distribution boards 4
Accessories for electrical services 4
Testing and commissioning of electrical services 5
Compliance with part L 5
Handover 5
As fitted drawings 5
Testing and commissioning 6
Introduction
1. For incorporation into project design briefs and employers requirements for design and build projects.
V21/Y73 - General lighting/luminaries and lamps
2. Lighting levels - the lighting level shall be as the appropriate room data sheet and be achieved with a power consumption of better than 9W/m2. The lighting efficacy shall be in accordance with the latest version of BB87.
3. Lighting control - control of lighting shall be by absence detection and daylight dimming. The lighting may be switched on manually but if no occupants are detected after a set time the lights will automatically switch off. Facilities for total room blackout shall be supplied.
V22 - General LV power
4. Cable segregation - cables of differing voltages and/or functions shall be segregated in accordance with the relevant standards or industry codes of practice. Cables shall not be tied to the outsides of other means of containment.
5. Cable supports - cable ties or P clips of any description shall not be used for the distribution of sub mains or final circuits. They may be used to support final flexes supplied to accessories or fixed equipment where fixing centers shall comply with the manufacturer’s recommendations for the flexes used. Data cables shall be run in cable basket.
6. Power outlets in IT installations - socket outlet final circuits in areas serving IT equipment shall comprise of no more that eight double socket outlets configured as a radial circuit in accordance with BS 7671 Appendix 15. The use of final ring circuits is not preferred.
7. General methods of wiring - generally the circuit wiring to the lighting and power shall comprise XLPE T&E, singles to BS 7211 in insulated or conductive trunking or conduit and armoured cables to BS 6724. It shall be enclosed within ceiling voids with wall drops enclosed in flush steel conduits. In areas requiring a surface installation wiring to be contained within white PVC trunking or high impact white conduit throughout complete with all accessories. Plant areas shall be singles 6491B to BS 7211 enclosed in galvanized steel trunking/conduit.
8. Earthing and bonding - in addition to the requirements of BS 7430 and BS 7671, all wet areas such as sinks, showers, bathrooms and similar installations shall have supplementary bonding applied to connect all simultaneously accessible extraneous and conductive parts.
V40 - Emergency lighting
9. Emergency lighting systems - systems where the emergency pack is an integral part of the main lighting are preferred. The method of test shall be fully automatic with visual alarm of the defective unit.
W50 - Fire detection and alarm
10. Fire alarm installations - fire alarm and detection systems shall be to a level of L3, unless specified otherwise within the design brief. Hard wired systems, using a proprietary and approved cable are preferred and any software systems shall be of open protocol. In new installations, the fire detection panel shall incorporate additional zones for future use, in keeping with the size of the installation.
W60 - Central control/building management
11. Control systems - all control systems shall have the capability to interface or be compatible with the Allen Martin system of building management. No piece of remote equipment shall incorporate a form of control that cannot be directly linked to the Allen Martin system. Any piece of equipment which utilises a LON works module shall not be used. Acceptable interfaces can include TCP/IP ethernet modules with the facility to communicate with and/or be compatible with Allen Martin controllers. All control cables to be VDE250 CY type. All instrument cables to be BS 5308.
Y71 - LV switchgear and distribution boards
12. Distribution boards - distribution boards shall be configured such that there is a minimum of 25% spare ways at the commissioning/handover of the contract. Outgoing ways shall be identified by a durable label that will last the life of the installation. Hand written board designations are not considered acceptable. Metering at final distribution boards shall include a v.f.c. to provide pulsed outputs at kW/pulse.
Y74 - Accessories for electrical services
13. Accessories - every accessory shall be labelled or engraved to indicate the circuit of the local distribution board feeding it. Where the role of an isolator or functional switch is unclear, it must be clearly and durably identified. Equipment supplied with a plug and located and fed under worktops or shelving shall be controlled and/or isolated with a suitably sized DP isolation or functional device. Accessory colour shall be agreed with the client early in the contract to provide compliance with part M of the building regulations.
Y81 - Testing and commissioning of electrical services
14. Equipment commissioning - where equipment and accessories such as ventilation fans, daylight dimming controls, occupancy sensors etc are fitted, the correct setting as required by the design specification shall be the responsibility of the installer for the following list. At least one weeks’ notice of the intent to commission shall be given to Cornwall Council’s clerk of works or senior contract manager (electrical).
• Lifting equipment
• Generators
• Electrically operating windows and doors
• Fire and gas alarms
• Any similar equipment
15. Installation commissioning and testing - the process of commissioning and testing shall form an integral part of the handover procedure. Testing shall be performed in accordance with the relevant standard or code of practice for the discipline; BS 7671 for electrical installation, BS 5839 for fire alarm installation etc. Commissioning shall follow the CIBSE codes one to five where applicable. Testing and commissioning shall be arranged in such a way that the Council’s clerk of works or senior contract manager (electrical) can witness the procedure.
Compliance with part L
16. All new buildings and extensions to existing buildings shall incorporate sub metering of lighting and power to comply with part L2 of the building regulations. As a minimum, lighting, computer power, mechanical plant power and catering power shall be considered.
Handover
17. Handover shall follow completion of the Council’s certificate of acceptance for practical completion. The documents to be provided shall be agreed with the Council’s clerk of works or senior contract manager (electrical) at least two weeks before the testing and commissioning and a period of time commensurate with the size of the project shall be allocated within the contract period for this activity.
As fitted drawings
18. A paper or electronic copy of all electrical drawings shall be maintained at site and shall record all verbal and written changes to the design or specification. This shall be used to provide the as fitted drawings.
Testing and commissioning
19. The testing and commissioning of all electrical services is of paramount importance and must be fully integrated into the project programme. All test certificates, manuals and commissioning data must be available to the supervising engineers in sufficient time for checking and agreement prior to handover of the building to the client. The project team must refuse acceptance of the building until these documents have been presented and agreed as there are legal health and safety implications for proving the compliance of many electrical systems with statutory testing procedures prior to occupation of the buildings.
Prepared by:
Chris Jackson
Policy and Training Manager
Property Services
4 August 2011
If you would like this information
in another format please contact:
Cornwall Council
County Hall
Treyew Road
Truro TR1 3AY
Telephone: 0300 1234 100
Email:
www.cornwall.gov.uk
Electrical engineering specification Essential elements 6
Version 1.0