A residual current device (RCD) is a special kind of trip switch that monitors the current in the live and neutral wires. The current in both wires is always the same unless electricity is escaping from the circuit somewhere, perhaps to earth or to someone who is touching a bare wire.

An RCD is so sensitive to differences in current that it can cut off the electrical supply literally in a split second before anyone can be killed. Ideally every house should have and RCD on the cables coming into the comsumer unit, so that the whole house, every wire, appliance and fitting is protected, making electrocution anf house fires very nearly impossible.

However, RCDs are relatively new and most houses still don't have them. In new houses, the RC may be the main switch in the consumer unit. To check if you have and RCD at the consumer unit, have a look for a small switch with a test button, which should be clearly marked RCD.

Fitting an RCD that will protect your home is a job for a professional electrician from the electricity board because the cables between the electricity meter and the consumer unit will more than likely need to be changed. However, you might need to fit an RCD to protect a separate circuit, for example, for sockets in the shower or sockets in the shed, garage or garden.

Always consult a qualified electrician before ever attempting to carry out any kind of electrical work. Safety first.Remember that electrical currents can kill.

Qualified electricians are readily available so be sure to call one out to inspect your electrical circuit before making any modifications.

I hope this article has been of use to you and will help you further when determining if you need to have and RCD on your supply.