The often misunderstood regulation concerning fires and cable supports…
Recently I was speaking to a builder who had been refurbishing an old terraced house and he was telling me about the electrician who completed the rewire.
The ceilings on the ground floor had been removed but were going to be re-boarded once the electrics and plumbing etc had all been installed.
The electrician nailed loops of steel banding onto the sides of the open joists and proceeded to wire the house by pulling cables through the loops. Needless to say this led to countless snags and nicks along the cables as he went along.
The builder asked the electrician why he was doing this and not clipping them as has always been done. He replied. “You can’t use pvc nail clips any more because of the 18th Edition Wiring Regulations”.
The regulation that this electrician is misinterpreting is…
521.10.202 Wiring systems shall be supported such that they will not be liable to premature collapse in the event of a fire.
Key points ‘premature collapse’ and NOTE 3 is where the confusion occurs.
NOTE 3: This regulation precludes, for example, the use of non-metallic cable clips or cable ties as the sole means of support where cables are clipped direct to exposed surfaces or suspended under cable tray, and the use of non-metallic cable trunking as the sole means of support of the cables therein.
In plain language and relevant to this situation…
Regulation 521.10.202 means that you can’t use pvc cable clips as the only method of support on an exposed surface, which is understandable.
However, the cables are going to be within the ceiling once it’s boarded so it’s not an exposed surface and as such pvc cable clips may be used. There is no possibility of premature collapse of the cables as the ceiling would need to have already collapsed before this is an issue.
Note, there’s no harm in putting a couple of metal straps over the cables after you have nail clipped them all into place if you have any concerns, but it’s up to you, I wouldn’t.