Earthing back boxes..

[mikeymoo]

A sparky told me today that you dont have to earth metal back boxes if they are RCD protected???? Right or wrong??

 

[adam.h]

I've always been taught to, so if there is an earth then yes I would.

 

[mikeymoo]

Thats what i told him. But he gave me the look of the devil
and snarled NO YOU DONT! lol i just walked away shaking my head.

 

[Spudnik]

You dont have to earth metal back boxes providing one of the plate fixing lugs is fixed.

Just be careful on singles as you have a choice of 2 adjustable, or 1 fixed and 1 adjustable.

Got nothing to do with RCD's.

 

[Bazspark]

A very useful piece of info i never heard before. In fact makes me wonder what else i dont know

 

[Spudnik]

Obviously if its a switch box, then all the earths get taken to the box and if a metal plate is used , a flylead to that.

 

[electro]

Its what your sparky mate doesn't know, that scares us...........

 

[mikeymoo]

If it scares you, how do you think i feel!

 

[Bazspark]

Did you know about the fixed lug Electro

 

[baldsparkies]

Its what your sparky mate doesn't know, that scares us...........

He is right in this instance though,
Its what my kitchen and bathroom fitter mates don't know that scares me.
And a lot more than another sparky.
I haven't come across a sparky that knows everything about our trade, and probably never will.

 

[Bazspark]

I Agree but i have certaintly come across a lot who think they know it all.

 

[electro]

Did you know about the fixed lug Electro

No I have never heard of that, sounds Good but possibly one of those things passed from sparky to sparky?, is it in the regs..?

 

[mikeymoo]

what if the insulations on the line conductor failed and the back box becomes live. The circuit protection device wouldnt trip? So i would say YES, earth the back box. I mean how long does it take..

 

[baldsparkies]

I Agree but i have certaintly come across a lot who think they know it all.

Yep, and those are the ones that truly give cause for concern. (Been in the trade since 1972 and still learning)

 

[Spudnik]

Come on fellas.

When the accessory is screwed back the earth connection to the box is provided through the fixing screw from the plate.

You will probably find the CSA of the screw is more then the 1.5 fly lead that would be connected.