A Rhetorical Question Ref Metal Switch Face Plate Earthing.

Mark Elvin · 12 Oct 2009

Whilst installing new stainless face plates to the sockets/lightswitch to replace the horrid white ones I was set wondering....

Whilst I have installed an earth wire between the metal backbox & the stainless face plate I started wondering what the regs said, as to whether the screws that attached the face plate to the metal back box would provide a sufficiently good earth to render the earth wire between the two excessive.

The continuity between the earth circuit (earth attached to back box) & the faceplate without the earth wire linking the face plate to the backbox is very good.

ericmark · 12 Oct 2009

Since the back box is not normally exposed many electricians do rely on the 3.5mm screws to earth the back box and 3.5mm diam = 9mm² so I can see their point.

However I have normally included a link wire between socket and back-box I suppose since I in the main worked on commercial premises where the back box was exposed to touch and often fed with conduit or SWA.

So to give a one size fits all answer would be wrong and some consideration has to be given to local wiring methods. [/code]

holmslaw · 12 Oct 2009

Mark Elvin · 12 Oct 2009

holmslaw said:
For the sake of a few pennies always fit an earth wire.

Like I said, I have fitted an earth between face plate & back box, I just wondered if it was overkill.

PrenticeBoyofDerry · 12 Oct 2009

Earth CPC to face plate is all that is required, the pig tail to the backbox is not a requiremnet.

ericmark · 12 Oct 2009

holmslaw said:
The fixing screws should not be relied as an earth for the plate.

Someone could change them to nylon leaving the plate unearthed.

The plate could be removed by say a decorator and when replaced the screws are not correctly tightend, leaving the plate inadequately earthed.

For the sake of a few pennies always fit an earth wire.

Good point made connecting an earth wire to plate and missing wire from plate to box may be OK.

But fitting earth to back box and missing out earth link to plate never should be allowed.

But although what "PrenticeBoyofDerry" says may be correct in most domestic it is not OK in all circumstances so one has to use some common sense.

Paul_C · 12 Oct 2009

The Regs. state that it's permissible so long as at least one of the fixing screws attaches the accessory to a fixed lug on the box. If both screws go into adjustable lugs, then an earth link is required.

Personally, I always include the link in all cases.

hairyben · 12 Oct 2009

so long as at least one of the lugs is fixed (non-adjustable) this is considered sufficient.

Gah, beaten!

holmslaw · 12 Oct 2009

hairyben · 12 Oct 2009

holmslaw said:
There is no such reg, its one or other of the self serving scheme providers that says its ok, as a sop to their members for their fees.

No it's not a reg, it's the NIC-EIC guidance on this frequently asked question.

Mark Elvin · 12 Oct 2009

I think the general consencus then is that I'm doing it the sfaest way by have a small earth link between the box & faceplate.

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A Rhetorical Question Ref Metal Switch Face Plate Earthing.

holmslaw

Paul_C

holmslaw

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