Class 1 light fitting - earthing?

[ADS]

Hi,

Has anyone got a good reason why I can't run an earth from the RFC to a class 1 light fitting.

I think I can - but am I missing/forgetting something.

No speculation or personal preferences, please, just regulation.

Thanks

 

[Evans Electric]

Ads , what does RFC mean ? Some of these abreviations leave me baffled TBH .

You can run an earth from somewhere on the same circuit as the light.

You could run one back to the board ,I suppose.

You can't pick one up from another circuit .

 

[Doc Hudson]

RFC Ring Final Circuit? ADS wants to earth the light fitting from the ring circuit by the sounds of it?

Doc H.

 

[kme]

If RFC is indeed ring final; then it will not comply with 7671. If you are happy to do it, and want to note it as a departure; that is your call.

I`ll post the reg. no. later, unless someone else has their book handy, and does it first.

KME

 

[Evans Electric]

RFC means Ring Final Circuit Eh!

Back to the question , situation is an unearthed light fitting , I suppose its better to earth it from the ring than leave it without one , if that is the best or only option open to you.

You will have left it safer than it was .

 

[Doc Hudson]

If the lamp was supplied via an FCU from the ring circuit it would be earthed from the ring. Would this be a better solution than taking an earth from a different circuit?

Doc H.

 

[ADS]

Personally, I don't see it as taking an earth from another circuit - an earth path is an earth path - I just wondered if there was anything anywhere that actually forbids you doing it...........no-one has come up with anything yet.

The situation is a hall light in a pre-war detached house........no earth whatsover to the lighting - light is actually fed with two dark-coloured singles, and that's it....no loop.

On the landing upstairs there is a socket whcih actually works out (electrically), at being about 1 metre away from the hall light.

So, is there a problem running, say, a 1.5mm single to the metal fitting.

Is it actually any different from applying supplemetary bonding - it's not a cpc protecting the light circuit......it's actually earthing an exposed conductive part.

Additionally, you are giving the light fitting a, near enough, 4.0mm earth path via the Ring Final CPC.

I honestly can't see whats wrong with it - but I will still be happy to be proven wrong.

 

[sellers]

The problem is that you nick the cpc from the ring circuit, 2years later ring has a fault on it, most of it is wired in Rubber cable customer has it rewired and therefore your lighting looses it's earth path!

Saying that I did it last week! Noted on cert and written on the cu! 'Circuit 1 uses cpc of circuit 5 do not disconnect'

 

[Doc Hudson]

As you imply ADS, in a real life fault condition on the lighting circuit, the actual path a fault current travels down may not follow the CPC of the lighting circuit itself anyway. A bathroom light, 16th edition, bonded to shower pipework & the electric towel radiator, (which is a spur off the sockets) could well have an easier route back to earth via the RFC, or the shower circuit? IMHO Sellers highlights the most hazardous point. Accidental disconnection during further alterations. I guess if you put a sign or note in the light fitting, in the socket, at the CU and on the certificate referring to the earth link, then it could be considered that you have taken all measures that is practical to do. The installation is safer than before you started work.

Doc H.

 

[steptoe]

I would have said no,

then post #8

your call, I cant give a reg to specifically forbid it,

just perhaps not best practice, but,

you are leaving it safer than it was.

 

[batty]

I would tell them lighting needs rewireing and would not put my name to doing such work but if you really are that desperate for doing this kind of work go ahead just ensure a note is put on consumer unit and your certificate you are going to give them.