My second query, as mentioned before I have trained so I can test appliances in my charities' premises.
I have come across a number of electric heaters which have an earth cable but the PrimeTest 100 won't let me run a class 1 test, I can only do a class 2 test. Other class 1 appliances have tested fine.
Can anyone explain why this is happening? Would a class 2 test be sufficient in this instance?
I'm not clear what you mean as the instrument not letting you run a class 1 test? Do you mean it's failing the heaters on the earth test? If so is the earth reading given open circuit (>99.99) or just a bit too high to pass?
If the heater is class 2 then it will have a class 2 'box in a box' symbol somewhere on it, if not then no it isn't acceptable to just assume it's class 2 - you need to establish why it fails the earth test. Is there an earth core in the flex?
Are you sure the metal work you are testing to is supposed to connect to earth (for instance metal fan heater grills may well not be earthed)? Are you trying to test through paint or anodizing - you might need to scratch through to bare metal?
If the bottom line is that the heater is metal encased and you are pretty sure it should be earthed and that you are doing the test correctly yet can't find a satisfactory earth then you should fail it and take it out of use.