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Main board in the house trips maybe one every two or three weeks? The MCB that feeds the sockets on one side of the house seems to be the culprit.
If i just flip the main switch back up it trips immediately, if i turn the MCB that feeds the sockets the main switch stays up, if i leave the MCB off for 5 mins it resets fine, then a week or two later the board trips.
All sockets test fine no obvious wiring faults, disconnected all appliances etc and still happens.
Never seen this before? Could the MCB be dodgy?
I'm not an electrician, but we had an MCB fail at the weeend, so they very much can be faulty, though ours just died and stayed dead.
Its doing my head in....
Have you done any fault finding on anything on the circuit that trips at all ?
try a new MCB - even swap two over
Quite possibly the MCB, I'd get that changed first, other option unplug everything on that circuit, see if it resets OK next time it trips.
Proper socket tester on all sockets and all good,checked all connections into back of sockets and inspected for bare wires.
Also "ahem" left all socket front plates loose and given them a "tug" (not that type of tug)
New MCB ordered but just wondered if anyone had a similar issue
Just posted on your other thread, Is the main switch an RCD? Is it the only RCD?
Main is an RCD, only one
Actually no the board has an mcb that feeds a workshop via armoured cable, the the workshop has its own RCD with an MCB for lights and an MCB for sockets
Presumably the main switch you refer to is an RCD (as it's tripping)? This is suggesting a there is a fault to earth.
Turning off the MCB that covers a set of sockets allowing the RCD to be reset suggests the fault is between live and earth (if it was a L-N the MCB would trip, if it were N-E switching the MCB would make no difference).
Is there a class 1 appliance on that set of sockets? (something with a metal casing that would require an earth e.g. fridge/freezer/washer/microwave) If there is I would start with checking the flex isn't damaged (obviously while unplugged) then swapping them to another circuit and see if the fault moves with them.
If it trips when there is nothing plugged in (even that hidden socket that you forgot about) then you need your installation testing.
Cheers
It could be moisture getting in somewhere on that circuit which can cause the RCD to trip.
Actually no the board has an mcb that feeds a workshop via armoured cable, the the workshop has its own RCD with an MCB for lights and an MCB for sockets
I presume the garage MCB, while in the main board, is not protected by the main board RCD?
No the garage mcbs are protected by its own RCD
I had something similar a few years ago in an old house when we upgraded the main board to one with RCD protection instead of fuse wire. Every few weeks the RCD would trip on the ring main. Turned out to be a poor earth on the house, electrician installed a new earth spike external to the house and never had the problem again.
That's a good shout, our earth spike was put in in 1996...
Just a thought, this is the first significant wet period we have had for a while, any correlation between wet weather and this happening? Have seen this type of thing happen before because moisture has gotten into the system somewhere.
As at least one of the posts above, it is not the circuit breaker that is faulty. It could be the RCD, or, more likely, as others have said, a fault on the socket circuit.
What make?
We have had a bad batch Wylex RCD's over the last year. They are about a year old, and just randomly trip, however, your fault sounds like it is a fault on the socket circuit. As you can turn it back on, only when the socket circuit is turned off.
Damp or rodents biting into cables is a common cause of this type of fault. Insulation breaking through in the back of a socket is also quite common, where the earth and live are slightly/almost touching.
I'd start by taking all the the relevant socket circuit faces off and checking for any crushed cables, or insulation damaged on the cables.
Fault finding can be frustrating and satisfying in equal measures! Last similar (seemingly random) faults I’ve come across were; immersion heater (fairly common), dodgy neutral in a socket that would sometimes touch the metal back box, damp in an outside light, rats!, combination of appliances that if all running at same time had enough earth leakage to trip the rcd, dodgy rcd (they can get overly sensitive with age). The most satisfying to track down was a wiring fault that if someone stood on an exact spot in a hallway, an old nail just come into contact with the cable. Took a while to work that one out!