Global Insulation resistance testing

[Gazthesparky]

I was doing a fuse board update the other day and normally I use duel RCD boards with mcb s but instead I used separate Rcbos due to the customer specifying these. I prefer fitting Rcbos due to just that one circuit is disrupted when there is a fault.

when quoting for the job I carry out a quick few tests which include a global L,N to earth to check for faults

then as I'm terminating the circuits on the day of the upgrade I carry out the insulation Resistance test on each circuit.

it then got me thinking can you carry out a global insulation test on the incoming tails like you use to be able to on Bs3036 boards

I haven't got my BGB with me at the moment it's at work but I'm sure that in there it states that RCDs should not be IR tested (plus they are sensitive to the test voltages) hence you can no longer carry out a global IR Test.


Im sure that you carnt carry out a global test anymore due to the RCDs /RCBOs but I just thought I would throw it out there and see if anyone has other ideas quicker ways to carry out insulation tests without having to do every circuit individually

 

[Octopus]

I'm sure that most of the people doing cheap EICR's simply guess the IR for the report!

As far as I'm concerned the only way to IR a board with RCD's or RCBO's is to disconnect them!

Unless anyone can advise otherwise??

 

[Dizzy_Maskell]

I've seen people test on 230v when RCD or RCBOs are used,
That will explain why they can do 3 Semi detached houses in a day full EICR and paperwork

 

[Guitarist]

How do you record the IR's for each circuit on your schedule of test results?
Global is fine for a "quick test", but I'd never use it as standard test procedure following a CU change.
IR test RCBO's at your own peril....

 

[Former Sponsor TM]

When I sat my 2391, our tutor taught that if you were wishing conducting a global I/R, then you would record the minimum values obtained and hence record this value on your schedule of test results. Obviously if any really low values were discovered then these would want further investigation.

Chris

 

[the pict]

Yep IR a RCBO and it makes a sizzing noise but only for a wee while
Pict

 

[Richard Burns]

If you wanted to do a global IR when you have RCDs and RCBOs, then just link all the lines from the top of the breakers (etc) together (out of the connections) and then test to the neutral bar and earth bar (and E-N).

Not quite as quick as a turn the MCBs on test but quicker than individual testing.
Global IR is a suitable method for testing, so long as you get good results, it is the bad results that then take the time.

 

[SirKit Breaker]

You cant IR RCD's/RCBO's, read the manufacturers instructions.

IR test of the full installation, if you do this, then as long as the reading is above the minimum allowed, then you record that result in all the appropriate boxes. I agree, and i also prefer one test one circuit, but that doesn't mean the other way is wrong, bad practice or whatever, it is in GN3 so it is good practice and we have to live with it. I dare say that in time this practice will die off, due to RCD's etc.

Cheers........Howard

 

[northeastsparx]

ive always done a global ir test before disconnecting the original board, saves the hassle once new board is fitted.
as said above never ir an rcd/rcbo.