How thick does steel protection have to be?

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Hi,

If I ran cable directly behind skirting, but wanted to protect it with a steel plate, not conduit. How thick must it be?

Thanks
 
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Hi,
If I ran cable directly behind skirting, but wanted to protect it with a steel plate, not conduit. How thick must it be?
Thanks
Have a look at Reg 522.6.5

How are you going to earth it?
....Conduit has to meet BS EN 61386 or
Trunking has to meet BS EN 50085 or
Be mechanically protected against damage sufficient to prevent penetration of the cable by nails, screws and the like. Reg 522.6.5 (v)
 
Hi.

The safeplates you get for covering cables across joist are 3mm thick if I recall correctly. The TLC ones are supposedly approved by the NIC or ESC. Would prefer to chase out myself, could be a right faff, not to mention the cost of getting the sheet steel made up.

Regards.
 
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You can get strips of 50mm and 75mm from eBay, 3mm thick.

Solder earth wire on at either end and connect them at the sockets with labels.
 
Hi,

If I ran cable directly behind skirting, but wanted to protect it with a steel plate, not conduit. How thick must it be?

Thanks

Probably be cheaper to put the circuit on an RCBO.
 
RCD protection does not allow you to run cables outside the recognised zones - only earthed mechanical protection/right sort of cable/burying >50mm deep will do - see 522.6.6.
 
As far as I can make out, there are two levels of protection to outside prescribed zones:
  • earthed steel conduit (or armouring etc) that still allows penetration (probably to earth penetrating nails etc before they reach a live conductor)
    non-earthed(?) mechanical protection that prevents penetration or buried at least 50mm
The site book simply states penetration protection is difficult to achieve.

"7.3.1: iv be provided with 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)."

I have to question the intention of the OP to run cables outside of prescribed zones, especially in a traditional area for mechanical fixings (skirting).
 
So what's the deal with the metal capping that most electrical suppliers sell to go over cables in chases?
It must be all of 0.5mm (or less) thick and wouldn't stop anything. I have drilled through this stuff before where cables have been run at a slight angle in walls etc. IMHO it offers no mechanical protection whatsoever, yet they still sell it and sparks keep using it. :cry:
 
I don't think metal capping meets any regulation for protection. I also don't know how it affects the current carrying capacity of cables except it encourages grouping rather than spacing cables 2 diameters apart.

EDIT: sorry, they should be 1 diameter apart in plaster but 2 diameters apart in insulation.
 
It's not for mechanical protection in the context of 522.6.6.

Its sole purpose is to keep cables from flapping around before they are plastered over, and can just as easily be PVC.

Some have it that it's also to protect cables from the edges of plasterer's trowels and floats etc, but I'm more inclined to believe the plasterers who say that a good edge on those tools is so important that it's ludicrous to suggest they'd risk damaging them by hacking at cables.

What is not in any doubt is that if, for whatever reason, a cable needs mechanical protection then capping simply won't do.
 
Capping is not mechanical protection - it's primarily there for two reasons - one as a method of holding the cables against the wall, and second to protect against the plasterers trowel (although many plasterers dispute this). This is why you can get PVC capping as well as metal etc...
 
I don't understand why earthed steel conduit is deemed sufficient protection for cables outside prescribed zones. It is often referred to as mechanical protection but I don't see it. All it seems to offer is to earth screws and nails before they hit live and that is only electrical protection. I suppose it is easy to detect.
 
Capping is not mechanical protection
Yes it is, just not in the context of protecting buried cables from penetration.

- it's primarily there for two reasons - one as a method of holding the cables against the wall, and second to protect against the plasterers trowel
There, see... you said it yourself! ;)
 

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