Help Required. electrical circuit problem

[OceanTragic]

(I hope this is an okay newsgroup for this article, if not, which other ones are more suitable.)

Today all the electrics went off in the house. My wife managed to insolate a problem electric circuit and hoped it had a blown fuse, but it wasn't that. The problem circuit provides electric power to half the house. All other circuits (7 of them) are fine.

When I put the fuse holder back in the fusebox and switch on the electrics the circuit breaker which protects the power to the house trips. When the fuse holder is out of the fusebox the power can be switched on without problem. I have tried using one of the other matching 30a fuses on the problem circuit and the same problem occurs.

I have switched off all fused-connection units on the circuit. I have unplugged all devices from all sockets. Still no joy.

I don't understand why the problem started as no changes to the electrical system have been made for a couple of years. The electrics are less than 15 years old.

Could the problem be that something in the ring has gone wrong? If so, what's the best way to test for this? Do I just need to check each socket and continuity test the circuit wires?

(Thanks in advance for any help)

[Rob graham]

At least you've isolated the circuit. You'll probably need to look inside each of the sockets on this circuit to see if a wire has come loose. I don't know why they should, but they just do, sometimes. The loose wire then may end up touching somewhere it shouldn't.

Rob Graham

[Bob Watkinson]

"OceanTragic" wrote in message news:dheiuq$532$ [e-mail]...

Right, this is what you need to do.

First. Don't panic, everything will be all right,

Second, In your fuse board take one a live and neutral from one leg of the ring so effectively you have a long radial circuit.

Third, split the ring at a socket , protect with terminal strip each end and energise with the fuse. If the fuse holds you know the fault lies beyond your split. If the fuse trips then the fault is before your split.

Fourth, repeat at various points until you identify the precise area where your fault is and then check this area out in detail.

To quicken the process ask yourself if any floorboards have recently been nailed down or any pictures or cupboards hung.

Good luck with it.

Bob

[Dane Koekoek]

Is there an immersion heater on this circuit? If there is, it might have blown, shorting itself out, tripping out the circuit. My parents had exactly this problem a few years back.

Basically take everything off the circuit and then reintroduce the appliances until one trips the power - then you've found the faulty appliance or wiring.

Dane

[Martin]

You have an earth leakage fault. Here's the clue "the circuit breaker which protects the power to the house trips". You're talking about the RCD - residual current device. It detects leakages of current to earth and protects you from potentially fatal faults.

Go around and disconnect/isolate every appliance on the faulty circuit - fridge, freezer, kettle, cooker, burglar alarm, central heating..... whatever is on that circuit, unplug/isolate. Don't miss anything! Now try putting the fuse back. Hopefully, your RCD won't trip. If that's the case, go round and reconnect, one by one, the appliances till you find the faulty one and take suitable action. If, with every appliance disconnected you still have an earth fault, call an electrician.

[OceanTragic]

Thanks for the brilliant advice, it has helped me alot but I'm a little stuck...

Great idea, I didn't realise I would be able to do this

I split the circuit at one socket and lots of sockets and the boiler FCU/power came online

As so many sockets had come online, I disconnected the first radial, connected the other radial and started testing it as it seemed to only serve 1 upstairs socket, 2 doubles and 1 FCU downstairs. I split the second radial into two and the upstairs socket, 1 double and

1 FCU came online, leaving only 1 double socket, which is quite close to the socket I used to split the original ring. I took this circuit apart and there was a little water in the socket (its near the sink - it wasn't me that put this in, or splashed the socket!). Aha, this'll be the problem then I thought, but no, as I replaced the socket with a new one and still got the same problem.. The problem must be in between the very first socket and the one that had the water in it.

The current situation is that I have power to everything, except rather than a single ring I have two radials. Is it okay to have two radials on from the same fuse in the box? There's obviously something wrong with the wire that would join the two radials together but I can't figure out what, or how to sort the problem out.

Any more ideas you can give me would be greatly appreciated.

[Bob Watkinson]

"OceanTragic" wrote in message news:dhh3pc$7j7$ [e-mail]...

By converting to a radial it allows you to test the circuit a bit of the circuit at a time. What you are doing is narrowing down the possibilities until you find the area where the fault is. When you fix the fault you need to restore the ring. If I understand you right you've now narrowed it down to a specific area. You now need to look at this area in detail. the water is suspicious. Is there a socket in the bedroom or whatever room is directly behind this socket? If so it may be only a few inches from your wet one and might also be wet. Is there a junction box nearby (under the floorboards) that the water may have run into by following the cable. If all else fails you will have to get the boards up and check the problem area in detail. Have you checked for nails, screws etc? Good luck, I think you're getting there.

Bob

[OceanTragic]

Due to other commitments I'm unlikely now to sort the problem out for a week. Do you think I'll be okay leaving the two radials on until then?

Looking at the lie of the sockets I think that they are directly connected, so I did a continuity test on the wires and got a perfect result. But there could be a socket or something somewhere, but Lord knows where. Both sockets are in the kitchen and the wires seem to run upstairs on one, but the other runs sideways and is puzzling. Behind the solid (two brick width) wall is my neighbour's garden. I'm starting to wonder if he's been drilling anything, but he'd have to drill through two bricks to affect any of my electrics, so I'm clutching at straws I think.

I think the floors will be coming up next weekend. Damn shame, wish I could figure out what the problem is.

You've been a great help.

Kev.

[Bob Watkinson]

"OceanTragic" wrote in message news:dhh5gi$2kp$ [e-mail]...

Yeah should be fine Kev

Did you test between L-N or L-E? A dead short would indicate the fault. Conductor continuity being ok doesn't rule out a fault on that cable.

But there could be a socket or something somewhere, but Lord

Not feeding a spur is it? Dish washer, Washing m/c, Central heating. If so switch of the cord outlets (or remove the fuse if it is this type) and retry.

[OceanTragic]

I didn't do either test.

The ends of each radial are wired into sockets (which work). Between the two sockets is the cable where the fault lies, which I don't think has any other sockets/units on it. The cable goes in to terminal blocks for each individual wire. I tested Live on one end of the wire to Live on the other end, and the same for Neutral and Earth. I got continuity each time.

Did this test prove anything or was it a useless test?

I guess it would have been useful to test Live at one end to Neutral (and then Earth) on the other end as I guess this would have proved any short between those wires. WDYT?

[Martin]

"OceanTragic" wrote in message news:dhhdqs$usb$ [e-mail]...

If you've identified (by elimination) the bit of ring cable that seems to be giving the problem, I suggest you by-pass that existing bit with a loose-laid bit of 2.5 T+E and re-test before doing anything more drastic. IME, the cable going faulty is less likely than something going pear-shaped with one of the adjacent sockets.

Also be aware that slight leakage in a number of places can "accumulate" to the point where it trips the thingy. So slight (and hardly visible) damp, for instance, in each of the kitchen / utility sockets - or the devices plugged into them - could be causing the problem.

Just my two volts-worth.....

[Bob Watkinson]

Martin is right. Can you bypass the problem with a new piece of cable either temporarily or permanently? If you can your problem is solved. Afraid your test didn't prove a lot really.

[OceanTragic]

I'll try the bypass next weekend and let you know what happened.

Thanks to both of you for your help; I wish I understood as much as you guys.

[Martin]

The RCD tripping indicates an earth leakage fault - that is a fault between L-E or N-E. (These days the correct terminology is to call both L and N "live" conductors - they're known as Phase and Neutral. Doesn't help you any, but it's a reminder that you can still get a shock from the N under certain circumstances.) Now a continuity test between L and E, and also between N and E, would show up a dead short, but a negative result (i.e. a high or "infinite" resistance) does not prove there is no current leakage path. You need an insulation tester that puts 500V across the conductors. It's then that you'd see the problem: the damp or the faulty insulation then shows up, but a simple resistance/continuity test unfortunately will not show up such a fault.

You dried out the end of the cable with a hair drier? Any sign of tracking/burned insulation on the end of the cable that got wet?

To sum up: if on that strip of cable now isolated, you get continuity between L and E or between N and E you have a dead short (continuity between N and L woulld have blown the fuse not the RCD). If your continuity test shows an "infinite" resistance between N-E or L-E then you have a breakdown of insulation (possibly caused by damp), and the 500V insulation resistance test would soon confirm that.

Before you rip up floorboards be absolutely sure there's nothing else on that isolated bit of cable - I'd call an electrician in to confirm things before I'd take up the floorboards.

By the way, now you've split the ring into 2 radials - the ring cable size (2.5 mm sq) could be inadequate for any heavy loads. By my reckoning, if you have anything 'heavy' on the circuit e.g. kettle, washing machine... you should be alright running ONLY ONE such item at a time. To play safe, run the kettle off the cooker outlet socket if you can and try and avoid using the washer till it's fixed. It's by no means ideal, and to be honest, what you are doing puts you on the wrong side of the law so if you c all an electrician in you might want to be a bit circumspect in how much you tell him you've done.

Keep us informed.

[Bob Watkinson]

"OceanTragic" wrote in message news:dhhgn7$kng$ [e-mail]...

No problem at all Kev. I'm an electrician by trade though my work is more management and IT these days. I'm sure you could blow the socks off me with your profession.

[Martin]

Hey, how do you think we got started ... same way you are. There's no substitute for experience.

Best wishes

Martin

[D. A. Hicks]

Just a quick question folks, if I have missed it in this thread I apologise

But having found water in the socket, is it not worth pondering where this has come from. has it splashed from a sink for example or roof leak, damp, condensation ? If this problem is not resolved, chances are you will never rectify the overall problem

David

[Martin]

Good point, David. Here's the relevant bit in Ocean Tragic's post:

"I took this circuit apart and there was a little water in the socket (its near the sink - it wasn't me that put this in, or splashed the socket!)."

The assumption is that it's water from the sink, but you're right: it needs to be followed through. And if it is water from the sink, the socket should not be in a position where it could conceivably get wet. He says the electrics are around 15 years old. That might be a rewiring on an old house - on the other hand, it could be a relatively new house, in which case you would think sockets would not have been placed so near to a sink.... or maybe not.

But in any case, the source of the water must be investigated.

Thanks for that.

[D. A. Hicks]

Ahhhh thanks, it's hard to be humble when one is as perfect as I ( LOL)

[Gavin Parsons]

A friend of mine went to a similar problem when he looked into it further he found that the lady in question had put a pot plant on a table in front of a socket and then watered the plant. Just goes to show you that you cant legislate for stupidity.

Regards