Insulation Resistance Help

[whazza22]

When carrying out insulation resistance test on a motor, do I test from D.B to the DOL Starter, then another test from DOL starter to motor? (is it ok to put 500v down tester?)

What about testing I.R for central heating system? - do you disconnect all the components and measure the supply cable, then measure each component separately on 250v?

When filling out test forms, what do you put in the insulation column if you measured some circuits on 500v and some on 250v?

Thanks