Re: RCD keeps tripping
Hi Lorna,
Can we confirm that the device that is tripping is an RCD and not an MCB? RCDs (the big main switch with a test button on it) is for earth-leakage protection, i.e. electrical faults shorting to earth. An MCB is a small switch that is used for short-circuit and overload protection.
If it's the RCD, the first thing you must do is go round and unplug all appliances, not just switched off at the socket, but unplugged altogether. The main culprits are washing machines, dishwashers, immersion heaters (switch these off if installed), electric ovens. Make sure you aren't using too many anti-surge extension leads - the type used to protect TVs and computers etc. These leads have a built-in leak to earth and if too many are used, the leakage could exceed the 30mA trip current of the RCD and if there is already a fault on an appliance, one of these extensions can just add to any fault current from a faulty appliance. I find it strange the an RCD would trip out if a lightbulb pops, this is usually a problem with an MCB.
I would be wary of anyone quoting for a new consumer unit without first having the wiring tested - if there is a fault, the new consumer unit with an RCD would still trip. What did he plug in? The boiler? If that tripped the RCD, I would suspect the boiler straight away, that could explain the RCD tripping and why it knocks off occasionally - the boiler tries to fire up at the times selected by the clock.
If it's an MCB that just trips, it could be, as you say, the computer - the transformer and or the cooling fan could have an internal short. Go round and unplug everything as I've suggested, switch the RCD back on and then go round and begin to plug in each appliance one at a time to see if the RCD trips. Leave the PC off for the time being to see if the problem is cured.
BTW.
If the property is only thirty years old, the wiring would be under the 15th Edition Regulations, hence an RCD (usually just one) and MCPs in the consumer unit. Any older than that and there would be rewireable fuses fitted. Do you know what make it is?
To be continued..........