Insulation Resistance test with 12v transformers

[Nicebloke]

I am installing a C/U and the kitchen has some old Down lights installed with 10 x 12 volt transformers connected. I know I could disconnect all the transformers but I don't plan to do that as it will be a real pain due to how the plasterboard has been bodged. Some opinions suggest the IR should be done at 250vdc, but the procedure states it must be done at 500vdc which clearly could damage the transformers?

 

[HandySparks]

I would omit the L to N test. Just do L+N to E at 500V.

 

[Pat H]

That's thje normal work around. test L&N connected together against Earth. No risk to the transformers then.

 

[Nicebloke]

Thanks chaps, that sounds the way to go.