There are three types of Safety Switch, so before you have them installed in your home it's important to know the difference between them.

1. Switchboard Safety Switches provide protection on electrical circuits throughout the house, and for those electrical appliances and extension cords connected to the protected power points.

It is advisable to install a number of Switchboard Safety Switches to protect individual electrical circuits, so that if a 'trip' occurs on one circuit, electrical appliances and lighting connected to the other circuits remain operating.

In general, current wiring rules require safety switches to be fitted for subcircuits supplying power outlets and lighting.

2. Power Point Safety Switches replace an existing power point, protect extension cords and electrical appliances plugged into the outlet, and protect some of the other electrical wiring and power points on the same circuit.

Unless a large number are used, the use of Power Point Safety Switches can reduce overall installation costs - their best use is for protecting electrical appliances in specific areas, such as bathrooms and workshops.

3. Portable Safety Switches protect portable electrical appliances and extension cords plugged into the Safety Switch.

Portable Safety Switches are essential for people using power tools or electrical appliances outside that are not protected by a Switchboard or Power Point Safety Switch. Where extension cords are used they should plug into the Safety Switch and not the power point, otherwise the extension cord will not be protected.

Nuisance tripping

Old wiring and electrical appliances, dirty or damp electrical equipment, heating elements and some fridges may have a normal earth leakage current which can trip a Safety Switch.

Earth leakage is increased with every additional electrical appliance plugged in, so a single Switchboard Safety Switch protecting all household wiring is more likely to have problems with nuisance tripping.

If a Safety Switch trips out twice for no apparent reason, don't ignore the problem. Have your wiring and electrical appliances tested by a licensed electrical contractor - they have metering equipment which can measure the earth leakage current of wiring and electrical appliances.