protecting non-RCD circuit wiring


S

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.
 
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A

ARWadsworth

sm_jamieson said:
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.
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
 
S

sm_jamieson

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 shouldbe
OK. Also note that there is no requirement to earth this 3mm steel.

Cheers

Adam
Excellent,
Thanks,
Simon.
 
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J

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 :)
 

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