Circuit Breaker

timetocallanexpert? · 6 Feb 2007

Hi, I hope one of you will be able to help me. I live in one of those houses where you start doing one thing and 100 more problems appear. Yesterday decided to replace a socket which had a worrying discolouration (looked like burning) around the pin holes. It's on a ring main, looks like a spur coming off it as 3 wires going into the back. BUT, when I wired it all back up again the circuit breaker on the CU will not switch back to on. Presuming I have an earth problem so tried to isolate the problematic wire from the back of the socket but even with all wires disconnected I cannot get the supply back on again. I know that the best advice and what most of you will tell me is to get a professional in to look at this but I just don't have the money (I know this sounds mean but am trying to look after elderly parents in their own home and there is nothing spare). I can completely isolate one side of our house (two different CU's) which I have done. Any advice on how to get the juice running again would be so appreciated.

I normally try to avoid the more complicated electrical/plumbing jobs, unfortunately what should have been a little job has turned into a larger one and I can't afford a professional.

Thanks.

breezer · 6 Feb 2007

since the fault was not there before you started and now it is, its logical to say its something you did.

have a look at the cables in the socket, are any touching the metal back box, i.e insulation breached

dingbat · 6 Feb 2007

timetocallanexpert? said:
the circuit breaker on the CU will not switch back to on.

When you say 'circuit breaker' do you mean a simple MCB, an RCD, or an RCBO?

If it is a live-neutral or live-earth fault you'd expect quite a violent reaction to being turned on. As you haven't indicated this it might be a neutral-earth fault on a residual current device.

Otherwise, it sounds like the breaker simply isn't engaging. Have you tried switching it ALL the way off, then resetting it to on? (All the way down, then back up)

FredFlintstone · 6 Feb 2007

Have you definately wired the socket correctly?

The CU will generally trip if there's current leakage to earth. Did you put any stress on the conductors (as in, did you try to pull some slack out of the wall to make wiring easier)? Did you make sure you never trapped the insulated conductors between socket plate and back box?

You could possibly have split the insulation somewhere which is causing it to earth.

Is there any un-insulated conductors visible at all or does the entire part of the un-insulated conductor enter the terminal on the back of the socket?

Have you definately connected the earth to the correct terminal and is it sleeved? Could there be any slack in it that's causing it to touch the other conductors or could it be that it isn't sleeved and is running close to the live terminal causing an arc?

Finally, have you tried another socket face plate? Could the new one be faulty?

Good luck

Fred.

JohnD · 6 Feb 2007

If the fault is not easily apparent:

1) The MCB might be faulty. Turn off the main switch in the CU and try turning the MCB back on. If it will not latch even with no current flowing, it is faulty. If it latches, but trips as soon as you put the main switch back on, you have a short circuit or massive overload.

If you haven't already got one, buy yourself a multimeter. You should be able to get one for about £8 in the high street. Be sure it has a Continuity setting (preferably with audible sounder) and an AC voltage range that covers 240volts A.C. (i.e. not a meter just used for 12v car electrics). Then come back and we will tell you what else to do.

If you can post a photo of the inside of your socket showing the wires and connections that will help. Also the outside of the CU and indicate which is the breaker that is tripping.

p.s. are all the earth wires in the socket box sleeved with green and yellow? If not and they are bare they may have touched something.

timetocallanexpert? · 6 Feb 2007

Thanks for that, I have checked the box out pretty carefully. After speaking to my Father it seems that the "push to test" on the RSC hasn't been working for years so there may be a bigger problem than I thought. Sounds like an earth fault. Does this sound like major work? How I wish I had left the discoloured cover on the socket!

The MCB will not latch even with no current flowing so guess that is the first thing to replace. I am going to try to get some photos on here to show you guys what I am talking about.

Thanks for all your help.

securespark · 6 Feb 2007

When you try & reset the MCB, does it make any noise?

FredFlintstone · 6 Feb 2007

Are you setting the MCB switch to the off position before switching it back on to reset it?

timetocallanexpert? · 6 Feb 2007

Ok, have a multimeter and have taken a couple of photos. Used multimeter to check continuity, the wire in the middle of the socket is shorting somewhere along the line. Any advice gratefully received, otherwise am going to take the box out of the wall and see if I can work out where this wire leads to, it may be a case of replacing with some new t&e.
Doesn't really sort out the problem with the CU though - it doesn't make any arcing noises or humming when trying to reset. The switch just flicks back to off. Even when the main switch is off on the CU it will not latch - does this definitely mean that it is b*ggered?

To look at the pictures please click here, couldn't work out how to upload to this forum.

Thanks.

Thanks.[/img]

dannyboi2003 · 6 Feb 2007

Hi,

Whereabouts in the UK are you, someone on here may be able to suggest a good electrician who wont charge you the earth should you not be able to fix the fault yourself.

From the problems you have described it sounds like several faults have come to light at the same time, i know you are not able to afford it but you may need to call an electrician to fix these faults.

All the best
Dan

dingbat · 6 Feb 2007

It's your RCD. It's obsolete and it should be changed.

FredFlintstone · 6 Feb 2007

When you say the wire in the middle is shorting, what are you doing to test this?

Are you connecting continuity tester to live and live of 1st and 2nd, 1st and 3rd and then 2nd and 3rd cable, then the same for the neutral and earth?

You'll get continuity for two of them because they'll be on the ring but one is a spur and won't have any continuity with the ring unless attached to the terminals in a socket.

Are you getting any cross continuity? That's to say, have you tried for continuity between live and neutral, live and earth and neutral and earth?

Fred.

timetocallanexpert? · 6 Feb 2007

Hi,

I have just checked continuity across all the wires and I am getting positives on
N1/N3
L1/L3
E1/E3

So this is the ring and the second wire (which for some reason I convinced myself was causing the problem) is the spur. But I am also getting cross continuity on

L1/N3
N1/L1
N1/L3
L3/N3

I am guessing that the insulation has been snapped (probably by me when changing the socket) inside the wire and that new t&e is needed?

Does this all sound OK?

I will get the RCD changed soon as I get the wiring back together! To be honest the whole lot looks pretty outdated but at the moment it's make do and mend time.

Thanks.

JohnD · 6 Feb 2007

The continuity you have found might also be caused by appliances (especially heaters) being plugged in and switched on. You have to unplug everything. Fixed appliances can be turned off at the wall switch/FCU.

If you do a resistance test across the wires where you find continuity that will give some indication of whether it is a dead short or not.

RF Lighting · 6 Feb 2007

Am I missing something here?

It appears to me that the live is connected through the RCD, but the neutral is NOT, thus preventing the RCD from holding in.

Perhaps the RCD was stuck, and switching it off has freed something up?

As the supply appears to be TT, the installation must be protected by an RCD.

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Circuit Breaker

breezer

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