Insulation Resistance Test

[mickmdt]

Hi all,
When performing an IR test, you are advised to remove all sensitive equipment, i.e. dimmers etc. My question is, do you leave the conductors open ended, do test and replace. What if you crunch it when replacing it. That makes it a waste of time doing the test in the first place. Isn't better to just do N-E, L-E and forget the N-L test?
This of course is only about new installs.
Mick

 

[telectrix]

if unsure about damaging equipment, short out L-N. test between L/N & E.

 

[ian.settle1]

If you have done an IR test with connection removed you should touch them done to earth to discharge them before reconnecting them.

Remember many years ago when working on a sub, some one was testing an indicator on the main control panel and in the test instructions it said to do this after carrying out an IR test and it wasn't, blow the ar$e out of a PCB board when it was reconnected.

 

[malcolmsanford]

It's always best when disconnecting the cables to have an apprentice holding the conductors to make sure the volts are getting through.

If your doing this on a new install I normally IR test before I fit lamps and plug things in. If you've already fitted things in then Telectrix is right you can do a 250volt test as per regualtion 612.3.2.

If it's on a PIR then as the competant person you will have to decide what tests and how you conduct them.

I would disconnect such things as a dimmer as they are quite straight forward, but rather than leaving bare conductors I would put them in a choc bock. A PIR half way up an outside wall while it is tipping it down would get a L/E test.

 

[WDMDL]

For a control device, eg dimmer, timer, etc you disconnect it and link through from the supply side to the load side. (Wago cage clamps are easiest)

For a luminaire etc you disconnect and leave open circuit. Again wago cage clamps for temporary insulation - don't create a high resistance fault with adhesive from insulation tape.

By applying the insulation test properly, ie releasing the test button before disconnecting probes, the circuit will be automatically discharged as the test button is released.

The only floating cable you should end up with is part of a 2-way lighting circuit. (You'd test all permutations) but leave the circuit in a state where the lamp would be ON

When IR testing is complete, you can short L and N together then both simultaneously to earth to completely discharge the circuit before re-connecting to the CU.

Simon.