Approved Document Part P: Electrical safety – dwellings

by Austin Williams
NBS Content Development Manager

The new Building Regulations Approved Document Part P: Electrical safety – dwellings, came into force on 6 April 2006. It applies to dwellings (and to business premises if fed from a common supply) and related areas such as stairs to flats, lobbies, shared facilities (including laundries and gymnasiums in blocks of flats); and to extended supplies for domestic purposes, e.g., supplies to sheds, greenhouses, garden lighting, etc.

The changes between this document and the previous one are minimal, comprising mostly presentational matters; re-ordering paragraphs, changing the order of information as well as helpfully précising some of the second tier information that had merely been referred to in the previous Approved Document P. The document that this replaces is only 18 months old and was designed in two parts: Part 1: Design, Installation, Inspection and testing; and Part 2: Provision of Information. Combining everything into a coherent whole is a sensible move, updating and simplifying it to be more reader-friendly.

There is now greater clarification about what activities are non-notifiable to building control bodies. Reference to ‘competent’ persons has been downplayed and instead, the new Approved Document refers to ‘qualified’ installers, which stipulates that the person certifying the works must have appropriate qualifications, knowledge and experience, although this still encompasses those registered with Part P competent persons self-certification schemes. With much more attention given to the testing and certification aspects of the regulations, it notes that ‘an electrical installation certificate can only be issued by the installer responsible for the installation work’ although, with regard to non-notifiable work, it says that there is no need to employ such a qualified person.

In Section 2, clarification has been added that material alteration and extension on electrical work need no necessitate the upgrade of the entire system, only that sufficient to ensure that the new work meet the requirements of the updated Regulations. However, if the upgrade is called for in order to meet the requirements of Approved Document L, then this proviso may not be invoked.

The Appendices remain the same, detailing the relevant testing and completion certification and testing schedules. The section on the new colour regime, which must now be used, refers to (but does not explain that) the protective conductor, neutral and phase, instead of the old earth, neutral and live.

The new colour regime is as follows:

The protective conductor: Green-and-yellow
Neutral: Blue
Phase of single phase circuit: Brown
Phase 1 of 3-phase circuit: Brown
Phase 2 of 3-phase circuit: Black
Phase 3 of 3-phase circuit: Grey

Related NBS information:

Articles:

• 17th Edition Wiring regulations
• Don't get your wires crossed: the colour coding of low voltage fixed wiring cable cores

Selected links:

• Electrical engineering

Written March 2006

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