Appendix A Purpose of Tests
45
Earth Bond Test
This test is to ensure that the connection between the Earth pin in
the mains plug of the appliance and the metal casing of the
appliance is satisfactory and of sufficiently low resistance.
A selectable test current is applied between the Earth pin of the
mains supply plug and the Earth Bond test lead clip.
A high current is normally used to stress the connection under fault
conditions. The length of the test should be limited to prevent
damage due to overheating.
Earth Screen Test
This test is to check the Earth screen connection using a current
which will prevent damage that may be caused by testing using high
currents. This is often required by sensitive electronics such as
computers and other Information Technology (IT) equipment.
A low voltage of approximately 100mV AC RMS is applied between
the Earth pin of the mains supply plug and the Earth Bond test lead
clip. A current of 100mA is allowed to flow for the duration of the
test.
Insulation Test
500 V / 250V d.c. test voltage
This test is used to verify that adequate insulation exists between
the mains supply pins and earth.
During the insulation test, a 500V DC voltage is applied between the
earth pin and both the live and neutral pins of the appliance mains
supply plug. The Tester displays the resistance measured and
allows the user to confirm sufficient insulation exists.
For Class 2 appliances, the Earth Bond Test clip can be used for an
earth return lead.
