Earthing metal backboxes

[Spoon]

What are the regulations on earthing metal backboxes? I vaguely remember reading a post about this a bit ago, but I cant find it on a search.
I has always of the opinion that the backboxes should be earthed, safer that way.
Any help would be appreciated. :smile5:

 

[Ponty Massive]

Don't have to be earthed as the screw from the face plate will technically earth it, however I always earth it as it's good practice.

 

[malcolmsanford]

Reg 543.2.7 concerns fly earthing boxes. It basically boils down to, if your using conduit, trunking, ducting or SWA or a sheath of a cable (MICC), then you must fit a fly lead in the box or enclosure

 

[Spoon]

Thanks for the help guys. This is for a couple of socket outlets in my kitchen.

 

[Marie-Claire]

any extraneous contuctive part has to be earthed in case under any circumstance it becomes 'live'

 

[malcolmsanford]

any extraneous contuctive part has to be earthed in case under any circumstance it becomes 'live'

Quite correct and back boxes are, but not necessarily by the use of fly leads

 

[topquark]

Must admit to being a bit of a die hard, I always fit earth fly leads to metal knock out boxes. When the screws are removed from the accessory then the box is no longer earthed if you have just relied on the screws (but of course you'd have isolated it first, right! ).

 

[telectrix]

Must admit to being a bit of a die hard, I always fit earth fly leads to metal knock out boxes. When the screws are removed from the accessory then the box is no longer earthed if you have just relied on the screws (but of course you'd have isolated it first, right! ).

less fun that way.

 

[sparkinlee]

Reg 543.2.7 concerns fly earthing boxes. It basically boils down to, if your using conduit, trunking, ducting or SWA or a sheath of a cable (MICC), then you must fit a fly lead in the box or enclosure

Malcolm, judging by your posts you're much wiser than I am in these matters, so I hesitate to comment, but my reading of that reg it applies in circumstances where you're relying on the trunking, conduit, etc to provide the cpc (presumably metal trunking etc, then!), and hence the connection between the back box and the accessory is the cpc connection to the accessory, rather than 'earthing' the back box.

Feel free to correct me if I've misread it!

 

[malcolmsanford]

Yes Lee your extending the CPC from the box onto the accessory.

 

[KFH]

I read an article on this in one of the mags or guidance notes which I cannot now find. It said that if at least one of the lugs on the back box was fixed then there was no need to put a fly lead in. However if both the lugs were floating (for adjustment) then it is necessary to put a flyleaf in. Personally I always put a fly lead in.

 

[Ryan_Moore]

My logic is: If it is metal, earth it.

 

[malcolmsanford]

My logic is: If it is metal, earth it.

I know Ryan that your just starting out, but you will have to first get to know the difference between an Exposed conductive part and then an extraneous conductive part, and then you will realise that statements like you just made are not only wrong but potentially dangerous.

Please by all means join in and ask questions if your not sure of things, but you need to remember that as this is an open forum and some people who will have less knowledge as you will feel this is a valid view point.

 

[telectrix]

malc. he's from liverpool. should have said " if it's metal, nick it".

 

[stevie2011]

I know Ryan that your just starting out, but you will have to first get to know the difference between an Exposed conductive part and then an extraneous conductive part, and then you will realise that statements like you just made are not only wrong but potentially dangerous.

Please by all means join in and ask questions if your not sure of things, but you need to remember that as this is an open forum and some people who will have less knowledge as you will feel this is a valid view point.

Just out of interest, can you give an example of a potentially dangerous situation?

exposed conductive part is something like a metal grid switch plate, or trunking part of the installation. I think, someone correct me

I cant work out what extraneous conductive parts are, even looking at definitions.

man i need to work on my theory.