Replace outside light - breakers tripping

Mr.Stu

Mr.Stu

Mr.Stu

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Joined
18 Oct 2002
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Not to be deterred by my previous failure I thought I would replace the outside lights with some up/down lighters to refresh the outside of the house.

Unfortunately I've hit another issue, and before I lose man points and phone the electrician, I'd like to check with your folks that I'm not missing anything obvious.

Before:

Everything working 100%

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After

Replaced one light. This involved screwing new mounting holes for the up/down lighter and screwing the wires in to the new choc-block.

It worked for a few minutes, then the RCB tripped, taking out all of the sockets downstairs as well.

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Now

To try and trace back my steps, I have removed the light, fitting, screws, just the bare wires are sticking out. If I turn on the smaller breaker for the downstairs lighting loop, it still trips the RCB?!

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Any ideas?
 
Did you drill these new mouting holes? Sounds like you have hit a cable some where mate.
 
Not drill, but yeah, new screws in different place (only wood) - if I've hit a cable it's not the one supplying the light as that can be easily seen from behind (inside the porch).

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Power off to the board. (Big switch on board) its just if all you have done is remove that fitting and screwed into that wood panneling then the fault is likely to be else where or the breaker has given up the ghost after a fault (chint are ****) no nicks in the cable where it's been stripped back?
 
I've not tried powering off the entire house/board. Is it just a case of power off the large switch, try the light-loop-B6 breaker again, and see if it trips the RCB? What will this show/prove?

Is it common for the actual breaker themselves to become faulty?

Cheers
 
You're going to have to start breaking down the circuit to see where the fault lies.
Start at the junction box and remove the cables going to the 2 outside lights, remove all of them by the way not just the live as a neutral/earth fault will trip an RCD too.
 
Ok

I removed the entire wiring to the outside lights, so whatever I touched today is completely disconnected.

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Still tripping.

Could I have killed the breaker in the fusebox by tripping it so many times?
 
It's unlikely to be the breaker as it's the RCD that's tripping.
It may be unrelated to the work you've done, try switching all the switches on the downstairs lighting circuit to the opposite of what they are at they moment then try the breaker.
If it holds, turn the light switches back on 1 by 1 to hopefully find where the fault lies.
 
Sorry was on my phone at work earlier. Didn't read properly that it's the RCD tripping, thought the breaker wouldn't reset.

Do as above, turn every switch off on downstairs lights and try again, switching them on one by one till you get a trip. If it's tripping regardless then I'd advise an electrician unless you want to tear downstairs lighting to bits.
 
It is tripping regardless of switch positions on downstairs loop.

Called the leccy, he came out and fitted a new breaker for the lighting loop - it fixed the problem, but as he was walking out the door it tripped again.

He isolated the circuit further removing the junction box entirely - problem persists.

Seems the fault is indeed unrelated to the work I did, but elsewhere on the downstairs neutral loop that spans four rooms.

He is coming back in the morning to isolate and test each light.

What a nightmare - all I wanted to do was replace my porch lights! :(
 
If it's still happening with all the lights switched off then yes it probably is a neutral/earth fault.
It does seem a bit of a coincidence that it happenend when you were working on that leg of the circuit though, I'd try removing everything else from that junction box just to see. It could be a faulty PIR in that porch light.

Edit; Forget that I just read that he tried it already...
 
Yup, currently disconnected and still tripping immediately when I enable the MCB for downstairs lighting.

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Electrician said it could be a weakness exposed elsewhere in the circuit when fitting the new light. I find it hard to swallow, as you say, its a massive coincidence - but still - we have completely removed that section of the wiring I worked on - so not sure what else to try now.
 
Not much you can try, need to track down the fault which can either be done trial and error or if it was me I'd be performing a IR test on the lighting circuit isolating legs as I went till the fault was found which I suspect your electrician will do tomorrow. Just plug a few table lamps in for tonight. :)
 
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