IR testing steel conduit on 1st fix?

[sheppy619]

Hi everyone,
I'm nearly on my AM2 test and really enjoy the industrial side of things so I thought I'd learn by asking.

I recently came across this note about IR testing PRIOR to connection? Can someone just explain how you would test if there was steel conduit and the earthing arrangement being on the other end of a building!?

"It is essential that, when performing an insulation resistance test between live and protective conductors, the protective conductors are connected to the earthing arrangement – that is, to the general mass of the Earth (Regulation 612.3.1 refers).

The connection to Earth is typically achieved by the protective conductor being connected to the main earthing terminal (MET) of the installation, to which the earthing and main protective bonding conductors are also connected, with the MET connected to the earthing arrangement (the distributor’s earthing facility (TN system) or the installation earth electrode (TT system), as applicable)."

Thanks everyone

 

[timhoward]

I recently came across this note about IR testing PRIOR to connection? Can someone just explain how you would test if there was steel conduit and the earthing arrangement being on the other end of a building!?

I think there are two things being muddled:
1 - testing when using conductive containment, or MICC cable
2 - final IR testing prior to energising.

For the final testing, the containment would need be fully installed and earthed before you tested.
Then you would test the conductors in turn against the CPC bar or MET, whichever is nearer.

For the intermediate testing, it's a matter of testing all conductors against the containment (or MICC copper outer)

I can't remember what you have to do to pass the exam, but it just seems common sense to me to make sure that any containment that is conductive isn't in contact with any of the conductors.