What dangers is a portable appliance test looking for?
What inspections and or tests are done on electrical appliances is dependent on the construction of the appliance under test; for ease we’re going to concentrate on the two most standard types – class I (earthed) and class II (double insulated but not earthed).
Class I equipment, for safety has an earth connection. The wiring in the lead and the appliance includes an earth wire.
If there is a fault within the equipment there is the possibility that the outside casing could become ‘live’ giving an electric shock if the earth connection is faulty. As a result class I equipment should have regular tests to ensure the earth connection is functioning correctly.
Double insulated equipment
Class II equipment is often referred to as double insulated as there is extra insulation within the construction of the appliance to prevent the casing becoming live (prevent contact with live parts), even if there is a fault.
Because of the double insulation the appliance doesn’t need an earth connection to maintain safety; so it will not need a portable appliance test if used in low-risk environments; although an insulation test is recommended (only when there are exposed metal parts).
However, regular user checks and visual inspections should be carried out as the integrity of the appliance case is a necessary to ensure safety is maintained – in other words if the casing is damaged the risk increases.