Any appliance that connects to mains electricity should be regularly inspected to ensure that it is safe to be used. Any item that fails this inspection should be identified, labelled and withdrawn from use until the fault is repaired.
Items that are physically wired into the mains need to be inspected, up to the mains interface, by service personnel, trained on that appliance. This is usually because the appliance is fixed in place or uses a larger current than normal and so is restricted where it can be connected. This larger current can cause more problems if a fault develops, but as the appliance is usually heavier duty, mainly operated by trained personnel, it is unlikely to be moved around and therefore, generally more protected from wear and tear.
Appliances that are connected using a plug and socket need to be inspected by a competent person. The relatively smaller currents involved can reduce the hazards involved, but the portability of these appliances can bring their own, more frequent problems; more use, more abuse, being moved to different locations, different operators, temporary cable runs. All mean that the appliance needs to be monitored, in case it becomes damaged or faulty.
Although, ideally, an appliance should be removed from use as soon as a fault develops, often the fault isn’t visible, is overlooked or it is given a temporary repair for convenience or to save money.
It therefore makes sense to have an independent inspection of all electrical appliances on a regular basis, by keeping a log and labelling appliances, they can be monitored to help prevent any from slipping through the net.
The IET suggest the following intervals for testing: