Cu change

[Lurch]

Nowt wrong with a borrowed neutral on a lighting circuit as long as they are both on the same RCD. I think it's infinitely preferable to have separate MCB's for the lighting circuits than keep them on one MCB because of the borrowed neutral.Of course if you can find and correct the borrowed neutral then you can have them on separate MCB's on separate RCD's

I'd change your username.

 

[Hawk81]

Nowt wrong with a borrowed neutral on a lighting circuit as long as they are both on the same RCD. I think it's infinitely preferable to have separate MCB's for the lighting circuits than keep them on one MCB because of the borrowed neutral.Of course if you can find and correct the borrowed neutral then you can have them on separate MCB's on separate RCD's

can't believe a qualified electrician would give advice saying there is nothing wrong with a borrowed neutral!!!!

 

[ProDave]

Consider............

DIY homeowner, changing his new landing light fitting that he buys from B&Q..

Turns off the upstairs lights...

Like wot it says in the instructions...

Take old fitting down...

Pops into the garage to get some bigger screws.. (cuz the ones in the box are always too small)

Comes back... Not knowing that little DIY jnr has pressed the downstairs switch to work the landing light...

DIY bob standing on his stool top of the landing grabs hold of the red and back wires, (its old wiring in his house!! ) to put them into the connector block..

WHAM!

gets a 230v belt between Line and Neutral....

Not path to earth .. So NO RCD trip's!!!!

That example is NOT a result of a shock due to a borrowed neutral, but a MISTAKE by the person changing the fitting thinking that all upstairs lights are on one circuit, and all downstairs lights are on the other. But unfortunately he didn't realise the landing light was fed from the downstairs light circuit.

That would have happened WITH OR WITHOUT a borrowed neutral.

The shock was a result of his failure to test for dead before working on the fitting, and a failure to isolate the correct circuit breaker for the circuit he was working on.

I fully accept a borrowed neutral is not ideal, and I understand the regs you quoted, but I don't believe it is quite as dangerous as you suggest.

 

[Apache]

That example is NOT a result of a shock due to a borrowed neutral, but a MISTAKE by the person changing the fitting thinking that all upstairs lights are on one circuit, and all downstairs lights are on the other. But unfortunately he didn't realise the landing light was fed from the downstairs light circuit.That would have happened WITH OR WITHOUT a borrowed neutral.

The shock was a result of his failure to test for dead before working on the fitting, and a failure to isolate the correct circuit breaker for the circuit he was working on.

I fully accept a borrowed neutral is not ideal, and I understand the regs you quoted, but I don't believe it is quite as dangerous as you suggest.

I disagree. If all the lights were on the same breaker then both would be isolated and the above situation couldn't happen. Period.

 

[ProDave]

I disagree. If all the lights were on the same breaker then both would be isolated and the above situation couldn't happen. Period.

So by your argument all sockets should be on the same breaker, in case he turned off just one ring final, and the socket he was changing happened to be fed from the other one?

It's common to find "upstairs sockets" and "downstairs sockets" but then find someone has added an extra downstairs socket as a spur from the upstairs socket circuit.

So the same danger applies, and not a borrowed neutral in sight. So do you agree when doing a CU change to put all sockets on one MCB to avoid the same danger?

 

[philbas]

So by your argument all sockets should be on the same breaker, in case he turned off just one ring final, and the socket he was changing happened to be fed from the other one?It's common to find "upstairs sockets" and "downstairs sockets" but then find someone has added an extra downstairs socket as a spur from the upstairs socket circuit.

So the same danger applies, and not a borrowed neutral in sight. So do you agree when doing a CU change to put all sockets on one MCB to avoid the same danger?

I think the point your missing is that with a borrowed neutral, the circuit can be energised fron two different sources, you can do all the tests you want to prove its dead, but the flick of a switch on another circuit makes it live again.

 

[ProDave]

I think the point your missing is that with a borrowed neutral, the circuit can be energised fron two different sources, you can do all the tests you want to prove its dead, but the flick of a switch on another circuit makes it live again.

No it doesn't. The LIVE for a particular light fitting only ever comes from one circuit, and nobody has ever got a shock from the borrowed neutral.

The other "danger" with lighting circuits is often the downstairs hall / landing light switch will have two live feeds, one from each circuit, so both need to be isolated before changing the switch. But again, that is not a borrowed neutral problem, though perhaps a better argument why the lighting circuits should be fed from one MCB.

 

[philbas]

No it doesn't. The LIVE for a particular light fitting only ever comes from one circuit, and nobody has ever got a shock from the borrowed neutral.

I really can't believe you said that.

Any Neutral that is disconnected is potentialy live. And there are several threads here detailing how people got shocks from shared neutrals.

 

[Andy™]

Nowt wrong with a borrowed neutral on a lighting circuit as long as they are both on the same RCD. I think it's infinitely preferable to have separate MCB's for the lighting circuits than keep them on one MCB because of the borrowed neutral.Of course if you can find and correct the borrowed neutral then you can have them on separate MCB's on separate RCD's

i suggest you go get an office job where your less likely to kill someone through your incompetence.

if you have a borrowed neutral, you can isolate a circuit, prove dead at the light, and it will show as dead. but as soon as you break the neutrals apart, one of them is now live.

and your trying to say this is safe?!

 

[Andy™]

and nobody has ever got a shock from the borrowed neutral.

FFS.

you may aswell say 'no-one has ever got a shock from a line conductor'

neutral is classed as live for a reason.

since your unable to understand basic electrical theory, ill go draw you a diagram.

 

[Andy™]

here's a diagram.

if anyone is unable to work out how you can get a shock from the neutral, i suggest you go try it in your own house. just make sure you call an ambulance first.

 

[kme]

nobody has ever got a shock from the borrowed neutral.

I have - more than once, unfortunately....

As Andy described it - tested - dead. Removed 1 neutral at rose, and it blew me off the step-up I was using.

What a ridiculous, ill-thought out & idiotic statement to make.

And your level of knowlege (officially) is what?

KME

 

[Andy™]

As Andy described it - tested - dead. Removed 1 neutral at rose, and it blew me off the step-up I was using.

this is the main reason why i always disconnect neutrals from light treating them as live until they are re-tested once parted from each other.

may be paranoid, but it keeps me alive

 

[kme]

So do I now; this was as a good few years back; when the scenario had never occured to me.

n.b. I note "pro" dave has a red dot......did someone disapprove?

 

[Andy™]

So do I now; this was as a good few years back; when the scenario had never occured to me.

almost the same here - but i noticed something wrong when it sparked when i removed from terminal

 

[Bacon]

The chap 2 doors down from me had a P***er from neutral on landing light while changing light fitting he asked me about it explained most likely borrowed NEUT from upstairs lighting.

Then asked me about changing C/U ols wylex rewireable in at moment,But did say NEUT needs sorting out before board gets changed.

 

[Hawk81]

No it doesn't. The LIVE for a particular light fitting only ever comes from one circuit, and nobody has ever got a shock from the borrowed neutral.The other "danger" with lighting circuits is often the downstairs hall / landing light switch will have two live feeds, one from each circuit, so both need to be isolated before changing the switch. But again, that is not a borrowed neutral problem, though perhaps a better argument why the lighting circuits should be fed from one MCB.

Are you for real??!! I seriuosly think you need to go back to school. You should not be handing out advice to anyone when it is clear you do not know what you are on about. To top it off you keep arguing when the other lads have clearly explained why a borrowed neutral is dangerous. PRODAVE what exactly are you a PRO at?

 

[m4tty]

Take it easy. I think prodaves input to this forum is great and everyones taking digs. we all get things wrong from time to time. Give him a break. Thought I'd logged onto the darkside for a minute there. Cheers

 

[Theorysparky]

[quote name='Andy

 

[Andy™]

now you have confused himold colours !!!!! :run

ooops....

i never even thought of that until you mentioned it!