Need a sparky! (Not going to carry out any work myself, just need some advice)

[Can'tWeld]

Hi,

Have just moved house and while the house is lovely it seems to have some pretty dodgy electrics.

The other day we noticed the lights flickering while we were upstairs - I wasn't particularly concerned about this until downstairs a few hours later, in the kitchen, I heard a "BANG" and saw a flash from somewhere under my worktops (near the sink), then another one and the breaker tripped out!

My thought is that I have a dead short to ground somewhere. The weird thing, though, is that the other day when this happened the washing machine lights were flickering on and off even though the breaker for the sockets was switched off!

It doesn't happen now with the other breakers on, but I have tried resetting the breaker (just to pinpoint the fault) and it doesn't happen immediately, but after about 30 seconds the same thing happens again - "Pop", a flash and the breaker goes. No lights on the washing machine this time though.

Other thing is that I was connecting a socket upstairs the other day with the socket breaker off and I decided to test the wires with a multimeter before starting - glad I did, as for some reason I measure 240 volts to ground from both the live AND neutral wires (0 volts between them) with the socket breaker off! WTF?

I'm not intending to do any work myself but I'd just like some advice really - I'm assuming I should be very worried about the aforementioned problem? Why would there be voltage there at all with the breaker off, not to mention on both the wires!?

I think the landlord needs to take a very good look at the wiring in this place!

He's a pain in the **** and hasn't had his phone on since Saturday, hopefully will see him today.

I do know a bit about electrics so it's mostly out of curiousity why I'm asking about this on here. I don't see why the wires would be live to ground with the breaker off.

Cheers.

 

[mike os]

definately needs a periodic inspection and should already have a landlords cert... if not he is breaking the law afaik.

 

[rtbcomp]

Sounds like a live is touching an earth somewhere.

When you say the breaker goes, do you mean an MCB or RCD?

If the Landlord won't play ball have a word with the Council, they have a department to deal with lettings, although you could end up falling out with your Landlord.

 

[Can'tWeld]

Hi RTB,

I believe it's an MCB at the main panel. There is an big bang and a flash when the fault occurs and it happens without any appliances on.

Weird thing is that the breaker doesn't trip immediately; everything comes on and then after about 30 seconds that's when the fault occurs.

Landlord is looking today (he's a qualified spark; exactly how qualified I don't know ) - I just hope he can provide a sensible explanation to the fault as otherwise I won't be able to relax in my own home.

Don't see how a ground fault can cause the live and neutral to both be hot with the breaker off though?!

 

[madkayaker]

i'm not to far up the road

 

[rtbcomp]

Hi RTB,

....... - I just hope he can provide a sensible explanation to the fault as otherwise I won't be able to relax in my own home.

Don't see how a ground fault can cause the live and neutral to both be hot with the breaker off though?!

You want more than an explanation!

If the neutral is floating and you have something on another circuit switched on (or some other path between live & neutral) and an appliance on the faulty circuit is also switched on then the live could bypass the MCB. A bit of a longshot perhaps, but something is dangerously out of kilter. He hasn't got live & neutral mixed up at the consumer unit has he?

Is there any damp in the walls near any sockets - I had a house that used to bang and flash when it rained hard.

 

[Can'tWeld]

Hmm, that seems somewhat plausible (having the wires connected up wrongly to the main panel, that is).

What would be the effect if he had done this? The Neutral is supposed to be bonded to the earth at the main fuse, right (so I don't have a live earth connection - I'm assuming this would definitely cause quite a big bang )

Presumably this means that if the MCB was switched off, it would sever the neutral line at the panel but there would still be voltage on the live, which would also appear on the neutral by virtue of there being a load (e.g. a fridge) connected across the two wires.

Something to suggest to him perhaps. Cheers.

 

[mike os]

if he does not know enough to check the conductors are correctly identified & connected......

 

[Can'tWeld]

OK...there's definitely some weird shizzle going on in my house.

Landlord came yesterday. He turned it all back on; no trip. Checked the visible sockets, found no problems. I, not being convinced, checked the ones behind the oven and tumble drier - no problems at all.

This morning, there I am messing about behind the sink trying to get the waste hose through for my washing machine. 5 minutes later, "THUMP!" socket breaker trips. Then... "THUMP! THUMP! THUMP" - it's still banging away even with that breaker off!

I turned the main switch off at the panel and replaced my trousers.

So... the immediate fault seems to be a fault to ground somewhere behind the sink. The undersink cupboard has a MDF panel on the back so I'm going to have to get that off and see if there's any wires or junction boxes back there that I've disturbed.

The landlord will come and have a look with me tommorrow and hopefully together we can find the fault.

The other fault, however, does seem to be that the CU is connected up backwards! Otherwise, why would there still be a live arcing to ground even with the breaker tripped?

Presumably the main switch (the big red one) on most CU's interrupts both live AND neutral, which would explain why the arcing stopped when that was switched off?

 

[rtbcomp]

The big red awitch is two pole, so it isolates both live & neutral.

Have you tried probing around with a neon screwdriver? They return to earth through your body, so can distiguish between a live and a neutral whereas a bulb or voltmeter can't.

 

[mike os]

i would want to know he is niceic, napit and or part P registered I'm afraid......sounds like he really does not give a toss & just going through the motions.

 

[brightspark]

you said your landlords an electrician is that on his grannies side christ all he had to do was test for correct polarity. disconect the row of neutrals in the fusebox turn off circuit breakers do an insulation test isolate faulty circuit. disconect the lives in mcb if its the ring circuit part the circuit at the furthest socket and work your way through testing as u go till u have isolated the faulty leg betwen 2 points .if he hasnt tested its just guess work .its obviously a damaged cable or joint shorting then blowing its self clear then shorting again due to the carbon build up and posibly dampness

 

[Can'tWeld]

Right, a real electrician came last night and we have (some) progress:

- The tails were connected up backwards at the CU!
- With them connected up the right way, the socket breaker trips immediately when turned on. Still a "pop" but at least it trips out now.

He's also found that the kitchen ring is broken.

With earth disconnected at one point in the ring the earth wire on the disconnected side goes live and the pop doesn't happen, so something definitely shorted to ground and probably an intermittent fault between neutral and live too.

I reckon a socket/junction box full of water.

Anyway, just thought I'd let you know for all those curious about what it was.

THanks for the help all!

 

[rtbcomp]

- The tails were connected up backwards at the CU! Ta da!

Did he find where the ring was broken? It could be in the same place where the short to ground is occurring. You may also have a faulty appliance somewhere, unplug everything in the house and see if that has any effect.

I saw this on a customer's site, a live came adrift and contacted the earth. The earth was broken so current went down the PC network cable and blew the PC up, and made the electric kettle live for good measure.

 

[the snooper]

sounds like frank spencer wired that house, how can someone get the tails the wrong way round ?
some dangerous people around

 

[Emmsy]

someone put a screw through the cable somewhere? more than likely the break is at same location as the short. have you removed all the kitchen sockets and just checked there is no wire popped out of a terminal and touching another?

 

[Can'tWeld]

I've checked all the sockets except one which is fillered to the wall. Anyway, spark is coming back tommorrow, Landlord is paying for him so no need to worry

It's just from the way the fault seems I think there's more than one wire getting bridged. Oh, also, the other day when I was troubleshooting I had a lamp plugged in in the kitchen which slowly came up to full brightness before the "Pop". This was with breaker switched off, though obviously this was before the tails were switched back round so the neutral would still have been live.

That's what makes me think water in a socket/junction box...that could short more than one wire, couldn't it?

 

[the snooper]

i would be very reluctant to use those circuits as it sounds like it could be a fire hazzard especially with the lamp getting brighter and brighter which may indicate arcing and heating up somewhere

 

[Can'tWeld]

Electrician did find the fault. It was with a cable under the sink, he reckons the fitter had put a screw through it when he fitted the kitchen units. Obviously when I jiggled the U bend around it moved the screw just enough to short things out!

Anyway, the wiring was a mess so what we've done between us is replace the entire ring main in the kitchen, so the old circuit is now dead and we know where everything goes now. Big job but it now seems to be 100%, feel a lot safer and as a bonus have a fair idea how to wire a room now

 

[rtbcomp]

That's a good result.