Any electricians out there?

[off_again]

Long shot here, but my main RCD keeps tripping out at home. Its gone three times in three days and I am at a loss to know what the hell is causing it.

I have a single RCD for the main supply and the older style fuses for the distribution box. The fuses arent burning out (then again the RCD would trip first) and as far as I can tell nothing is blowing like a light bulb.

Tripped earlier when I was out at the dentists - so nothing switched on, no major surge on the power (or so I think) but still tripped out when I got back.

Where the hell do I start?

[Jon C]

Quite a good one I heard of, was a guy whose mains kept tripping in the middle of the night. Turned out that he had forgotten to turn his pond pump off for the winter, and as it froze overnight, trip. Come morning, reset the switch, water in pump had already melted, off it went, untill next time. Might be worth a check.

[sheepy]

Try removing fuses and see if the breaker still trips. Should help you isolate which circuit has the issue if you can do it one circuit at a time.

You may find it's something like a wiring fault (rodent damage etc).

If you can work out which circuit has the problem, post back and see if anyone can help you further.

Sheepy

[rsvmilly]

sheepy said:

Try removing fuses and see if the breaker still trips. Should help you isolate which circuit has the issue if you can do it one circuit at a time. You may find it's something like a wiring fault (rodent damage etc). If you can work out which circuit has the problem, post back and see if anyone can help you further. Sheepy

As Sheepy says, work through the fuses.

If it is on a 30A ring main circuit it could also be a faulty appliance. I knew somebody who's microwave would trip the rcd ever time you opened the door.

[Byff]

Could be your fridge is on it's way out. That's my first guess, but if it's happening at random times of the day and after no particular event i.e. Cooking, dishwasher, washing machine, then it'll be a bugger to find.

Good luck on your hunt.

[off_again]

Thanks chaps - fridge and microwave are new, and cooker (although old) hasnt been used. As I dreaded though, could be faulty wiring or something plugged into the circuits. Its going to be a pain to find it.

Anything that can be used to check the cabling? Got a circuit tester, but I aint putting that near the mains electricity - I havent got a death wish yet anyway.

[turbobloke]

Hardly dare suggest it but RCD devices can surely be faulty...tried another from another room?

[wedg1e]

I had this a few times after I moved in here. Eventually I traced it to a length of lighting twin-and-earth that was routed across a joist in the loft. Most times when I went up there (have to use the loft a lot, it's only a small bungalow) I would stand on the cable. After some indeterminate time, all the power would go off. The insulation was breaking down where it had been crushed by my size 8's.

[motco]

Bear in mind how an RCD works; it checks the current flow in the live and neutral conductors and, if there's difference above a certain level - say 300mA dependent on the device - it trips. Any current being syphoned off to ground causes an imbalance in current. It isn't, in principle, a current sensor in the usual sense in that it isn't load dependent. Whatever and wherever the fault is, it must cause a loss of current to ground; that might give you a clue.

[Pigeon]

300mA is a lot... think there's an extra zero there

Sheepy's suggestion of pulling fuses one at a time to determine the faulty circuit is a good one.

Things with heating elements are likely suspects - immersion heater?

[turbospud]

rcd trip because of leakage ie what goes aint returning if its covering the whole supply its harder to detect,first off is to unplug everthing,determine weather its on the wiring or an appliance,then separate the light circuits,then socket and imm circuits.most common areas is where moisture and elec meet,kettle,iron,dishwasher,outside light other things to look for are incorrectly wired appliances,brought anything in to the house recently?