When PAT testing appliances it can be confusing, and sometimes difficult to remember, everything you learnt on you PAT testing course once you are starting out in your career.
We often get asked about earth leakage and touch current testing and the difference between the two.
Earth Leakage
An earth leakage
test for class I appliances is carried out in order to test the amount of current leakage through the insulation. No insulation is perfect and there is always an amount of leakage even if this is nominal.
Earth leakage testing will establish the level of this leakage and if this level is safe enough for use.
Touch Current
A touch current test for Class II appliances is carried out as class II appliances do not have an earth.
There are two different methods of testing procedures that can be used. One is a probe test where an earth bond lead is used as a probe to measure any current leaking onto the enclosure or casing.
The other method is to use a differential test. The test meter will measure the amount of current being supplied to the appliance and how much current is being returned before calculating the difference.
For the pass/fail limits, page 77, table 15.3 of the IEE Code of Practice 3rd Edition will provide the information required.
It is important to ensure that you have completed, passed and understood your PAT testing course before beginning a PAT testing business.
