Wiring Regulations for domestic installations: nails, walls, and earthing

Wiring Regulations for domestic installations: nails, walls, and earthingThis article is a continuation of, Wiring Regulations: New or rewired domestic and similar installations – both articles being inspired from the Industry Standards and Guides on the ESC website. Below you can find some of the most asked questions when it comes to attaching / fixing TV’s on the wall, driving nails into walls, etc – and the Wiring Regulations.

If the mains supply cable to a fixed appliance such as a flat screen TV is concealed in a wall or partition at a depth of less than 50 mm, does the 17th Edition require the lead to be RCD-protected in accordance with Regulation 522.6.102 even though it’s connected by means of a plug and socket?

Yes. The risk of penetration by a nail or screw is the same as for other concealed cable. Also, if the wall or partition has internal metallic parts (except nails and screws, etc), RCD protection in accordance with Regulation 522.6.103 is required irrespective of the depth of the cable from the surfaces.

More info: see Regulation number(s) 522.6.102, 522.6.103

Should signal amplifiers mounted at high level on television aerials where they might be struck by lightning be main bonded?

There is no specific requirement in BS 7671 but, if there is considered to be a significant risk of a lightning strike, the advice of a lightning protection specialist should be sought.

What types of mechanical protection provide sufficient protection against penetration by nails, screws and the like?

As an example, steel of 3 mm minimum thickness is generally considered to provide sufficient mechanical protection, except where shot-fired nails are likely to be used.

More info: see Regulation number(s) 522.6.101, 522.6.103

Can accessories and electrical equipment such as socket-outlets and under-cupboard lighting be fixed to fitted kitchen units?

Yes, provided that they are securely fixed to rigid parts of the units that are not demountable or otherwise liable to be disturbed in normal service. However, care must be taken to comply with all the relevant requirements of BS 7671, including accessibility for inspection, testing and maintenance, and provision of adequate protection against damage (by impact or water for example) for the accessories, equipment and associated wiring.

More info: see Regulation number(s) 530.4.2

For more information and Industry guidance on the wiring regulations in the UK, especially the 17th edition, visit the ESC website (Electrical Safety Council) website. Some of the most frequently asked questions concerning the new or rewired domestic and similar installations can also be found on their website.

What is IP Zoning? Update on the IP rating and IP zoning: zone 0, zone 1, and zone 2 only!

We owe our visitors and customers an apology – the recent regulations have modified the “IP rating in the bathrooms – bathroom IP zoning” and the “IP zoning in the bathrooms – IP rating“. It is a simple change – the renouncing / eliminating of the zone three, since it is irrelevant when it comes to light fittings and other electrical devices in the bathroom or shower.

Zone 3 has been removed under the 17th Edition Wiring Regulations BS7671. To illustrate the IP zoning regulations there’s the classical bathroom area divided up into areas or “ZONES” which are classified using the numbers 0, 1, and 2(no longer a zone 3).

The luminaires are assigned an “IP RATING“(which can be seen in the description of the light fittings on our website) which indicates how much protection they provide against ingress of water and other particles.

Each zone has a minimum IP requirement that must be met if a fitting is to be installed in this area. The source for this picture and details: the Aurora Lighting Information on the IP Zoning in the Bathrooms.

IP Zoning in the Bathrooms – the IP Rating and Zones

  • IP Zoning – Zone 0 – Inside the bath or shower. Any fittings used here must be SELV (max. 12V) and have a minimum rating of IPX7 (protected against immersion in water). If there’s the likelihood of water jets being used for cleaning purposes, a minimum of IPX5 is required for the light fittings or electrical devices.
  • IP Zoning – Zone 1 – Above the bath or shower to a height of 2.25m. A minimum rating of IPX4 is required. If there’s the likelihood of water jets being used for cleaning purposes, a minimum of IPX5 is required for the light fittings or electrical devices.
  • IP Zoning – Zone 2 – This is the area stretching to 0.6m outside the bath or shower and above the bath or shower if over 2.25m. An IP rating of at least IPX4 is required. The same as in zone 1 – If there’s the likelihood of water jets being used for cleaning purposes, a minimum of IPX5 is required for the light fittings or electrical devices.
  • IP Zoning – Anywhere outside zones 0, 1, and 2 – this is where water jets are not to be used for cleaning purposes, the general rules of BS7671 apply. IP not essential – IP rating is not required.

IP Zoning in the Bathrooms - the IP Rating and Zones

In zones 1 and 2, SELV or 240V luminaires may be used(remember to respect the IP rating required). As for the final circuits, they all require 30mA RCD protection.

Please Note: The above information is intended as a guide only – if you want to find out more detailed information on the IP rating and the IP Zoning in the Bathrooms, please refer to the IEE Wiring Regulations(BS 7671:2001 section 601).