Settle this Argument.

[telectrix]

metal faceplate 1363 socket. obviously needs to be earthed. argument is whether the back box should be earthed just because it's a metal faceplate. ( i know it's considered good practice to fit a fly lead anyway, but that's not the argument. the argument is with the faceplate being metal, does that make any difference. my argument is No, other party says Yes. Who is right, going by BS7671?)

 

[Ian1981]

I would agree with you.
Perhaps if the back box was exposed such as surface clad metal boxes then I would fly lead to the back box as well, only because the back box is more accessible to touch than in a wall if the socket face plate was ever removed for testing etc the back box is still earthed.
You can argue it's the same thing I suppose.

 

[Andy78]

No, it makes no difference regs wise. The regs ask for earthing of exposed conductive parts. That's been done already.

 

[kingeri]

I can't see what difference it makes if the faceplate is metal or plastic myself. So I agree with you.

Incidentally, I have noticed that the practice of earthing metal backboxes seems to be dying out, along with doubling over smaller conductors (especially CPCs).

 

[polo1]

If the backbox has one fixed lug, not required ( but I'd do it anyway). Two adjustable lugs, fly lead required, IMHO irrespective of plastic or metal accessories.

 

[Andy78]

I can't see what difference it makes if the faceplate is metal or plastic myself. So I agree with you.

Incidentally, I have noticed that the practice of earthing metal backboxes seems to be dying out, along with doubling over smaller conductors (especially CPCs).

I was on a facebook sparkies group and doubling over was brought up. All the younger guys chimed in "You don't have to do it with modern terminals" Clearly some garbage they are repeating in training centres. This was about an 80% consensus.

 

[Wilko]

My 20p - both need earth, from reg 411.4.2 which in part says "each exposed conductive part". But is a recessed metal back box an exposed conductive part, or is maybe deemed to be ?

 

[Ian1981]

Well hager specifically say in their consumer unit instructions that wires 1mm and below require doubling over into the terminals.
That's their guidance anyhow.

 

[Ian1981]

My 20p - both need earth, from reg 411.4.2 which in part says "each exposed conductive part". But is a recessed metal back box an exposed conductive part, or is maybe deemed to be ?

GN 1&8 suggests that it's an exposed conductive part and is part of the enclosure for the wiring accessory so should be earthed

 

[David M]

GN 1&8 suggests that it's an exposed conductive part and is part of the enclosure for the wiring accessory so should be earthed

Though I don't disagree with bonding the box, I cant see how a buried boxed is classed as exposed? I think its a grey area, which is simply covered by over kill bonding that is simple to install & unobtrusive any how, so why not fit it.

 

[telectrix]

the back box is earthed anyway by the 3.5mm faceplate screws until or unless the faceplate is removed. in which case, the circuit should be isolated first.

 

[Octopus]

I very much doubt that 7671 states this clearly either way!

Like many other regs.

.....

 

[David M]

the back box is earthed anyway by the 3.5mm faceplate screws until or unless the faceplate is removed. in which case, the circuit should be isolated first.

I mentioned this way way back during conversation with an inspector. He said though this is true they cannot be relied on for bonding purposes therefore the back boxes should have additional bonding.

 

[Ian1981]

Yeah the text book answer is that the socket would be isolated before removal but we all live in the real world and sometimes you need access to the terminals for any live testing or for fault finding etc.
Plug in testers are not a way in proving dead as far as I'm aware tho we all use them I'm sure.

 

[Strima]

Not forgetting DIY decorating when the faceplate is pulled away from the wall for papering or painting.

 

[telectrix]

Not forgetting DIY decorating when the faceplate is pulled away from the wall for papering or painting.

true, but we'renot talking about what may or may not be desirable. we're talking about what the regs. stipulate. was around 2003 i think, in an amendment to 16th. where the stipulation for not earthing a back box was changed from 2 fixed lugs to single fixed lug.

 

[Risteard]

I mentioned this way way back during conversation with an inspector. He said though this is true they cannot be relied on for bonding purposes therefore the back boxes should have additional bonding.

But you're not bonding it - it's not an extraneous conductive part. You are earthing an exposed conductive part. Although a separate conductor is not required with one or more fixed lugs I personally would always do it.

 

[The Ghost]

543.2.7 Where the protective conductor is formed by metal conduit, trunking or ducting or the metal sheath and/or armour of a cable, the earthing terminal of each accessory shall be connected by a separate protective conductor to an earthing terminal incorporated in the associated box or other enclosure.

 

[Ian1981]

That regulation ,is if say you used metal conduit as the cpc.
A tail Earth from the back box is needed connecting to the socket faceplate or to whatever the accessory serves as.

 

[The Ghost]

Would you have a metal surface box on anything else? i.e. galv etc.