protecting non-RCD circuit wiring

[sm_jamieson]

OSG has says a concealed cable is OK if:

Provided with a mechanical protection sufficient to prevent penetration of the cable by nails, screws and the like (Note: the requirement to prevent penetration is difficult to meet)

Would it be acceptable to screw an earthed 3mm mild steel plate (Get some cheap from metal supermarkets) over the wiring in a chase ? Obviously it should be wide enough to protect from a hole drilled at an angle. This might be a convenient solution if only a part of the route needs to be protected.

Also, it seems you could run protected cable anywhere, not just in the safe zones, but it would not be a bad idea to still use the safe zones.

Thanks, Simon.

[ARWadsworth]

Here is a quote from the NICEIC Essential Guide

1.4 Condition (c) - mechanical protection sufficient to prevent penetration Condition (c) provides for a cable to have mechanical protection sufficient to prevent penetration of the cable by nails, screws and the like. Regulation 522.6.6 does not require the mechanical protection to be earthed. In general, protection of a concealed cable against mechanical damage from nails, screws and the like is achieved by metal at least 3 mm thick. However, it has to be recognised that, in some circumstances, mechanical protection may not be sufficient to ensure that a cable cannot be penetrated (for example, where fixing methods of other trades include shot-fired nails). In such circumstances, this method of protection could not be considered to afford compliance with Regulation 522.6.6 and would therefore be unacceptable.

So unless you intend letting someone loose with a nailgun then you should be OK. Also note that there is no requirement to earth this 3mm steel.

Cheers

Adam

[sm_jamieson]

Excellent, Thanks, Simon.

[js.b1]

BS Electrical Conduit is 2mm wall CDS tubing.

However 3mm or 1/8" is a common thickness of plate and it is robust enough to support a thin plaster skim successfully. It is wise to specify 3mm so people do not use thin 1/16-inch or worse steel capping thinking that does anything.

You could of course just take the piss and mill an oblique slot along electrical conduit :-)