Originally posted by 6E524F545E5F485D555E3A0 link=1270768890/3#3 date=1270799832
Not a true test... But good.
Some might say why not 100%. The issue is that the usual test with a multimeter is at low voltage and potential... Thus a meter with a a tenth (0.10) of a mm gap will show OPEN cct. Yet a 680v (240Rms) may well have the potential to cross that air gap.. Add a bit of moisture and carbon dust and the normal meter might say 300meg.. Apply a megga and it might test as good as a SHORT.
That is why mega testers usually have a 250 / 500 and 1000 v test ranges to ensure that the insulation resistance; is true and realistic.
And yes, I have on the odd occasion measured and found OC with a normal meter and then smoked the unit when turning it on... Dont take chances any more.

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