My house was rewired 3 or 4 years ago and I have never had a problem with it but now the RCD is switching the electricity off as soon as I reset it. I have found that the problem circuit is the one for the kitchen sockets and have disconnected everything and switched off the boiler that is also on the circuit but this does not help. Is there anything obvious I can check or do I need to get an electrician in? Thanks, TC
The obvious questions are:
Have you changed anything recently, like fitted something in the kitchen that involved drilling/screwing/nailing that could have damaged a cable?
Are you sure you have disconnected all appliances? With the boiler for example are you sure its switch is a double pole one? Any appliances with hidden connections like washing machines, cooker hoods etc? The most likely cause is a fault in an appliance (especially ones with big heaters).
The other possible causes would include water ingress somwhere (boiler is a prime candidate), or cable damage causing a Neutral to earth fault perhaps. Do you know what type of earthing arrangement your supply has[1]
You could certainly do some basic checks with a multimeter if you are happy taking the cover off the consumer unit and disconnecting the cables for the kitchen sockets from it.
[1] See the following if you need more explanation for this:
If you're absolutely sure there are no other outlets on that circuit, such as a cooker hood, or the igniter for a hob, the only easy check you could do would be to take all sockets off the wall far enough to check whether anything has come adrift behind one.
I had this problem in my garage, and discovered that a mouse had explored a surface-mounted socket through an unused cable entry knock-out. It tripped the rcd at the time, I now realise, but I was able to immediately reset the trip. The mouse became unwell, and after a couple of weeks became so unwell that the rcd tripped again and wouldn't reset. I thought it was just a mass of cobwebs when I poked my finger behind the socket, but soon realised cobwebs tend to be rather drier. There are very few people on whom I would wish this experience (well, not all that many), so I hope your kitchen problem is less unpleasant.
Make sure all the plugs are pulled out too -- just switching off isn't necessarily enough to stop a faulty appliance tripping an RCD.
Thanks for all the advice. I (think I) have disconnected everything and have checked all the sockets for loose wires but the circuit still causes the RCD to trip. I think I'm going to get a pro in and hope it doesn't need rewiring!
TC
next step is to test the ring circuit the sockets are on with a multimeter to see if insulation is bad. Sounds like a wiring problem on that ring. Find the problem and at worst you just need to replace one bit of cable. At best just poke a wire back where its meant to go.
NT
The electrician that came today decided that its probably due to dampness in the roofspace area where the cable must goes - into a junction box he thinks. This would be a real pain to redo and so for the time being he's taken the circuit off the RCD for me to put back later when things might be dryer. Not ideal but at least I have hot water now! TC
Do check with a multi meter that you haven't got any Earth to Neutral shorts anywhere, these can cause real headaches and aren't that obvious until some current starts flowing!.
As to pro's.. I've yet to find one who knows what goes on with an RCD!....
The more relevant point is that the roof space is damp at all.
Its not the wiring that needs attention, its the roof.
Take this as a cheap warning of a potentially expensive problem that you now have time to address with some urgency.
Get up there with your flashlight!
Now, whilst its pissing with rain!
Note everything and take pictures!
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