agbtester wrote:Could anyone verify the difference on an insulation test between a class 1 and a class 2 appliance.
I understand a 500v dc voltage is applied between phase / neutral and the earth return path of a class 1 appliance, and between the phase / neutral and the test probe for a class 2 appliance.
Yes, that's exactly right.
It's generally outlined on page 75 of the IEE Code of Practice, and the method will be more specifically described in the instruction manual of your PAT instrument.
Re my query on the issue of testing a class 1 appliance with a long cord with a PT250.... an earth continuity fail result leading to a halt on the test.........and confirmation the test should have been a pass if the cord resistance had been subtracted.
Isn't this the same (insulation) test if you place the probe to an earth point on a class 1 appliance, and apply a class 2 insulation test....to overcome my issue of a halt in the class 1 test procedure.
I can see where you coming from with that.
However... have a look at pages 55 & 56 of the IEE CoP, specifically sections
11.1.3 (
Class I construction incorporating unearthed metal separated from live parts by basic and supplementary insulation) and
11.1.4 (
Class I construction incorporating unearthed metal separated from live parts by basic insulation and earthed metal).
If you were to unwittingly connect your test probe to one of these unearthed metal parts (if present on the appliance under test), and ran a Class II insulation resistance test, which passed with flying colours, the fact that the metal parts were unearthed could be masking an insulation breakdown on other parts of the appliance, between the live parts and actual earthed metal.
A Class I IR test would not be prone to this potential fault masking.