RCBOs (INSULATION RESISTANCE TEST)

[dkent5]

The insulation resistance test is for the cables only and not the equipment. The RCBO should also be marked down on your results sheet as equipment vulnerable to tests. For test purposes all the cables to this RCBO would be disconnected. The tests would then be carried out on the circuits protected by the RCBO and would not be a safety issue as the supply should be isolated to perform such tests. Hope this has been some help.

 

[WayneL]

Hi,

Once again...I might be wrong but -

I thought IR testing was to test for leakage - bit like pressure testing a pipe!!

If you disconnect all circuits before IR testing them and then connect them back up (after your

sattisfactory readings) then there is a chance that you may accidently short circuit something when re-

terminating the circuits.

I think this is why we are told to terminate everything before IR testing.

If an rcbo is going to be a problem whilst testing you can:

a) Test at 250 v

b) Replace with an mcb for testing purposes

But....as I posted before- this should only be a problem if the rcbo is part of the circuit that you are

testing.

If you are doing individual circuit IR testing at the CU then you are testing on the outgoing side of the

MCB/RCBO with all switches off so I don't think this will cause any damage.

Disconnecting all the circuits kind of defeats the object of IR testing - IMHO


Wayne,


Wayne

 

[Spudnik]

RCBO's are only single pole so the neutral, in effect is still connected even with it in the off position.

 

[WayneL]

Hi Jason,


What would be the answer then if you're IR testing a board full of RCBOs - disconnect their neutrals for

the tests? - or would you disconnect circuits altogether, like some have suggested?

Cheers,

Wayne

 

[Spudnik]

I would disconnect them altogether.

Test, then reconnect.

 

[lister]

im with moog on this one

 

[ianlwi]

hi mate, listen to lockhes, i always disconnect the earth & neutral from the rcbo before ir tests. when they ask you to test 3 rcbo's & do ir tests do they mean test trip times on those circuits both the mechanical & with the meter, i would be careful meggering rcbo's for 1 theres a coil in the rcbo even doing tests at 250v gives dodgy readings (gives you the impression there is an insulation breakdown on the circuit) 2 there is an above average chance of killing the rcbo. some rco's even say on the side to disconnect before insulation resistance tests. hope this helps.