Electrical safety checks are performed to minimise risk of electrical shock and fire hazard. They include visual inspection and various tests.

Equipment Classification

Earth Resistance
Class I equipment only.  Measure between the earthing pin of the supply plug and all accessible metal parts on the equipment. Maximum resistance <1 Ohm.

Insulation Resistance
Using a Megger ohmmeter set at 500Vdc (or set at 250V for items containing a MOV), and measuring between live parts (active and neutral) to earth, the reading should be >1M Ohm. (Alternatively, not greater than 5mA current flowing in the Protective Earthing conductor.)

For equipment with mineral insulated metal sheathed elements, the Insulation resistance can be >0.01M Ohm.

Class II - Measuring between live conductors and exposed metal parts >1M Ohm, or alternatively not greater than 1mA leakage to any external metal.

For details refer to AS/NZS 3760:2001 2.3.3.2