RCD tripping whilst the other stays on

[Christopher Meehan]

Morning all,
Whilst washing my car with our power washer the wife turned on the kettle (both were using kitchen sockets) and tripped out one of our RCDs. We have an old house and the kitchen sockets are with the upstairs and conservatory whilst the remaining rooms downstairs are on a different circuit and RCD.
Whilst unplugging everything as soon as the cooker was turned on (different RCD) it would flip the kitchen RCD but not its own one.
The problem RCD has the kitchen and upstairs, boiler, and the lighting for the whole house. It has been replaced but it is still tripping if any of the kitchen sockets are used. It will also trip if the cooker or every 30mins to an hour. My alarm is now out of battery so once this RCD flips it's going off as well.
My wife did say the hoover blew up earlier in the week but was using the downstairs sockets not the problem RCD circuit.
My electrician has been checking sockets but can seem to find anything. Any advice or help would be great.
Chris

 

[EFLImpudence]

You presumably have a fault to earth on one of the circuits protected by the RCD that trips.

If it trips every time the oven is turned on, it would seem to be relatively easy to determine which circuit it is even with no specialist equipment.
Turn off the MCBs one at atime and see if the tripping stops.
If it still trips the RCD with all the MCBs turned off then the fault is a Neutral to earth fault.
This will entail disconnecting the Neutrals from the consumer unit one at a time.

Once the circuit has been determined then find the fault by isolating parts of the circuit.

Other than an actual wiring fault, prime suspects are heating appliances and water ingress somewhere - outside light ???

 

[Christopher Meehan]

Found the fault. Electrician had to take parts of our third bedroom apart. Previous owner must have done some DIY putting his own sockets in and then managed to screw into the wires. Good job the room needed renovating!
Cheers for the help.

 

[EFLImpudence]

Well done. Glad you found it.

 

[chivers67]

Might be worth putting the alarm on a non RCD circuit too