Run earth from light switch to mainring

[rapido79]

No earth in lighting switch

Hi there, I don’t know too much about electrics so don’t get shocked, this may be a big no-no to do, here it goes any how.

Is it appropriate to run and connect an earth cable from the lighting switch (where there was no earth due to old cabling) and connect it up to the earth in the main ring via junction box?

Can this be done or is this not allowed and totally stupid?

Reason is I don’t want to drill walls but can access the wall next to the door frame and want to fit a metal switch.

Thanks

 

[ColJack]

as long as you have plastic switches and plastic lights, then there's no need to put earths to your switches...

running a seperate earth from the ring main ( SOCKETS... lights are on a radial ) is a no-no...

 

[ericmark]

It states some where in regs that the earth must follow same route as feed cables and any earth that is not part of main feed cable must be 4mm sq min.

As a result to add earth cables to an existing installation is as much work as to replace cables.

 

[ColJack]

ah yes, but adding earths isn't Notifiable, whereas replacing the entire lighting radial is..

 

[rapido79]

as long as you have plastic switches and plastic lights, then there's no need to put earths to your switches...

running a seperate earth from the ring main ( SOCKETS... lights are on a radial ) is a no-no...

Thanks for the response.

I have earth in the ceiling rose and it is connected. I just don't have earth in the cable that runs to the switch. So I was told that it's ok to have metal lights but to have plastic switch.

So i can not connect separate earth from switch to main ring earth, why is that? Why is is important from earth point of view that light os on radial, and main ring is a complete ring loop?

Apologies, as I mentioned do not know too much about this.

 

[holmslaw]

..

 

[rebuke]

My parent's house was wired that way - earth at the light fittings, but not the switches. The previous owner had rewired the house at some stage himself, and obviously decided to skimp on the switch cable (or perhaps squeezed it down some existing conduit or similar, which wouldn't fit T&E).

 

[ericmark]

I would guess reason that it must follow same route is so any fault with disconnects earth will likely also disconnect supply.

543.6.1 Where overcurrent protective devices are used for fault protection, the protective conductor shall be incorporated in the same wiring system as the live conductors or in their immediate proximity.

If you go here and down load "ESC Best Practice Guide No.1" this details the recommendations of what to do where the earths are missing.

 

[Space cat]

I would guess reason that it must follow same route is so any fault with disconnects earth will likely also disconnect supply.

That would be my guess also. I don't know exactly what the people who wrote the rules were thinking but I can see the logic in keeping things simple and predictable. If you go to work on an unfamiliar circuit you don't want to find unexpected quirks in it.

To take a worst case example, you have to work on the ring main and, in the process, you break the ring in two places, earths included. You now have a dangerous light switch. It gets worse. What if you remove a section altogether. Would you think to check that no other circuits relied on that section for their earth connection?

Regulations or not, it's bad practice. Don't do it.

 

[sm1thson]

That would be my guess also. I don't know exactly what the people who wrote the rules were thinking but I can see the logic in keeping things simple and predictable. If you go to work on an unfamiliar circuit you don't want to find unexpected quirks in it.

I think its fair enough the regulations dont cover every silly thing you could do wrong, the book i imagine is big enough and you are expected to use your head and not follow things blindly. Theres probably a number of daft things you can do without breaking a regulation that doesnt make it right. The regulations are a minimum standard (although naturally departures will apply again its using your head).

 

[ricicle]

If there is no CPC to the switch then not only must this be plastic but the switch box must have plastic (nylon) lugs.
Rewire the switch drop is the best option.

 

[ban-all-sheds]

Regulations or not, it's bad practice. Don't do it.

It's also bad practice to continually pepper your posts with ridiculous numbers of unnecessary smilies.

Don't do it.

 

[Space cat]

Sorry!

 

[Pengwyn]

[/quote]
It's also bad practice to continually pepper your posts with ridiculous numbers of unnecessary smilies.

Don't do it.[/quote]

who says so ?

 

[holmslaw]

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