It’s all change for the colour identification of fixed wiring as the UK is harmonised with the rest of Europe:
Due to be introduced this April, the new colours will be required for all installations starting on or after 1st April 2006. Guiliano Digilio, Head of Technical at the Electrical Contractors' Association (ECA), explains what the changes mean.
For the last twenty-eight years, the UK has used the colour blue for neutral conductors and harmonised brown/blue/green and yellow colours for the identification of the cores of flexible cables and flexible cords. This is set to change as the IEE Wiring Regulations (Requirements for Electrical Installations) BS7671, which for some time has been based on a common European standard document, is harmonised with CENELEC (the European Committee for Electrical Standardisation). International harmonisation of cable colours was not considered to be a viable option and so the planned harmonisation applies only to Europe.
UK out of step:
The UK had previously agreed with CENELEC and IEC to the harmonisation of cable colours for flexible cables. However, no similar agreement was reached for harmonisation of non-flexible cables used for fixed wiring. This resulted in the UK becoming out of step with the rest of Europe where most countries were standardising on blue for the neutral conductor with brown or black phase conductors.
The divergence between the UK and Europe was compounded by the new European Standard EN 60466 2000 that requires the use of the colour blue for the neutral conductors of fixed wiring throughout Europe. A Working Group to consider the position that the UK should take concerning colour harmonisation was set up by the BSI/IEE committee responsible for the technical content of BS 7671.
The Working Group concluded that the UK would have to agree to use the colour blue for the neutral conductor and brown for the phase conductor of single-phase circuits, and that due to widespread European adoption, black would have to be used for one of the other phases of a multi-phase circuit. In addition, the Working Group proposed that for a three-phase circuit the colour grey be used. This would enable phase colours to be identified without any ambiguities.
The recommendations of the Working Group formed the basis of a UK proposal which was accepted by CENELEC as the best way forward to provide a pan-European harmonised colour identification system for both flexible and non-flexible cables and cords and power distribution cables.
MUST be used from 1st April 2006:
The BS7671 amendment introducing the harmonised colours is 'BS 7671: 2001 Requirements for Electrical Installations Amendment No.2 March 2004', due to be published on 31st March 2004. Under the amendment, the harmonised colours can be optionally used from 1st April 2004 and must be used from 1st April 2006. Installations starting on site prior to 1st April 2006 can be started and completed in 'pre-harmonised' colours. However, 'pre-harmonised' and 'harmonised' colours should not be mixed. A new installation started during the two transitional period should be in either one set of colours or the other.
Other colours:
The new harmonised system does allow for other colours to be used in particular circumstances. For example, Pyro or multi-cored armoured cables, BS7671 allows identification by either colour lettering or numbering. Thus, blacks (or any colour) with say 1 - 7 can be used or they can lettered L1, L2, L3, N, E etc. For phase conductors in special applications and contol application cables can be brown, black, red, orange, yellow, violet, grey, white, pink or turquoise. No other markings will be required. If these colours are used for a.c. power circuits the alpha-numeric markings of table 51 should be applied at terminations. But under the new BS EN harmonised 2,3,4 and 5 core cables will only be available in the brown phases or brown, black, grey all with blue neutrals and green/yellow CPCs.
Termination-over-markings:
The new amendment requires that termination-over-markings is applied ‘except where there is no possibility of confusion’ at interfaces (the joint between pre-harmonised and harmonised cables) In practice, the installer will need to take a view on this but a new Appendix 7 with Amendment No. 2 suggests no marking is required for most single phase correctly coloured interfaces. For 3 phase, Appendix 7 suggests applying L1 L2 L3 and N. The Appendix places the responsibility with the installer, who if uncomfortable with interpretation, is recommended to always apply the interface marking in 3 phase installations
This is an important development and change for fixed wiring. The main safety concern is the role reversal of the colour blue and black changing from phase and neutral to neutral and phase. This may lead to confusion and possible accidents if electrical operatives and personnel are unaware of the changes. It is, therefore, thaty the new cable colours and the requirements of the IEE Wiring Regulations Amendment No.2 of BS7671:2001 are communicated and promoted to the electrical contracting industry. ECA will be playing a major role in this promotion and advises contractors to ensure that all operatives are aware of these and that tool-box talks for operatives of engineers are provided. Contractors are also advised to plan ahead, liaise with their cable suppliers and pre-order stocks of the new harmonised cables if necessary.
The ECA has produced a comprehensive guidance document to the proposed harmonisation. 'ECA professional guide to harmonised cable colours' is available from ECA, tel: 020 7313 4800, or download from www.eca.co.uk.
Electrical Contractors' Association
ESCA House, 34 Palace Court, London W2 4HY
Tel: 020 7313 4800
Fax: 020 7221 7344
Email: [email protected]
Web: www.eca.co.uk