OP
NickD
I always disconnect the circuit and do 250V for insurance then 500V if the 250V is clear.
So you totally de-energise and open up the CU (messing near live tails) just to IR test the pre existing circuit as part of a MWC-able addition? Fair enough if you were in there anyway for R1+R2. But if you weren't... it just feels a bit full-on. Just my 2p's.