Insulation Resistance Test For Minor Works

[NickD]

Clive: none of it is rocket science really, I just think I'm missing something. Looks like what I'm missing is that everyone else is opening up the DB and disconnecting the live conductors for the circuit purely to do IR testing. Which kinda surprises me on a small MWC job but if that's what you have to do it's what you have to do.

 

[Octopus]

Clive: none of it is rocket science really, I just think I'm missing something. Looks like what I'm missing is that everyone else is opening up the DB and disconnecting the live conductors for the circuit purely to do IR testing. Which kinda surprises me on a small MWC job but if that's what you have to do it's what you have to do.

Correct. Unless you take the cover off the CU and disconnect the L & N you won't get an accurate reading.

 

[NickD]

See, I *knew* there was a reason it couldn't be as difficult as I seemed to be making it...

 

[shanky887614]

Which puts test voltage E-N across the entire installation (maybe damaging stuff), and hence potentially up to L through connected equipment elsewhere in the installation (damaging more stuff)? Unless you disconnect N for the circuit at the DB? or leave the fuse in/MCB close and (L+N)-E test the entire installation?

i think it mentions it in the onsite guide.

you link l+n together and test to e

(l+n to e)

for transformers e.g. selv+pelv circuits like lighting in bathrooms.


it should be perfectly safe to do this at 250v