1) The Formal Visual Inspection. Appliance, cable, fuse, plug and socket inspected for signs of damage or faults, any issues to do with these are fixed where possible.

2) The Earth Continuity Test (Class I appliances and leads only). This test runs a current between the earth pin and the earthed surface of the appliance, to ensure that in the event of a fault with the insulation, the current will be safely drawn away and the appliance surfaces will not become live with 230 volts.

3) The Insulation Resistance Test. A current is passed along the live and neutral wires of the appliance. This test ensures that the electrical insulation of the appliance is sound and does not present a shock hazard.

4) The Polarity Test (extension leads only). This ensures that the leads have been correctly wired, to prevent equipment connected being affected by any problems with the lead.

Microwave ovens are also checked for radiation leakage.

These tests should be carried out at the intervals based on the guidance given by The Health and Safety Executive and the Institute of Engineering and Technology, as comparing results from previous tests can reveal developing faults in equipment before they present a hazard.