First of all, you need to establish what circuit breaker is that’s tripping the supply. Is it an MCB, cartridge fuse, fuse wire or an RCD?

MCB’s, Cartridge fuses, or fuse wire are only in place to protect the cable from overloading and causing a fire, they do not protect against any form of electric shock! Some of the reasons why these trip are: if you draw more current than the circuit breaker is designed to take, this could be something as simple as, too many appliances being plugged in. They will also trip in the event of a short circuit and this could be between live and neutral, or live and earth, this could also be caused by faulty equipment being plugged in, or water in an outside light etc.

An RCD’s is very different, these detect potential current leaking to earth and are normally rated at 30ma, 100ma, or 500ma. They do this by detecting any imbalance between the live and neutral supply, so if your RCD has tripped, but your MCB or fuse is still in the on position or intact, then you have a fault that’s leaking current to earth. This again, could be caused by faulty equipment being plugged into the circuit, and just because the socket outlet is switched off, it doesn’t mean that the neutral and earth are disconnected from the faulty equipment, on some socket outlets, only the live wire is switched.

If you can’t get hold of an electrician and it’s an emergency situation, try unplugging all the equipment, switch everything off in your consumer unit and then switch on the RCD. Now switch on one circuit at a time to see if the fault is still there. If the MCB or fuse that you’ve switched on trips the RCD, then that circuit or something on the circuit will more than likely be the cause of your fault.

At LCD Electrical services in Norwich, Norfolk, all circuits are wired to the latest regulations (currently the 18th edition) and will be supplied via a 30ma RCD. 30ma is the recommended amperage that can travel safely throughout the human body and cause no harm to life. Anything above this, like an old 100ma or 500ma RCD’s are now not compliant, and even worse still, if you don’t have an RCD fitted, it will take the current rated on the MCB or above, to be reached before the circuit disconnects!