testing elv downlights

[doglog]

Hello, can anyone give me some help on testing. I need to do an Insulation Resistance test on a lighting circuit with 24 ELV downlighters on it with individual transformers. I can do the live/earth and neutral/earth by testing live and neutral together to earth but the live/neutral test always gives a reading (obviously) even with the lamps removed (again obviously). I know if there was a live/neutral fault the breaker wouldnt set but is there some way to carry out this live/neutral test without disconnecting all the transformers.
Thanks for your help
Paul

 

[monkeyelectric]

Just as you say test between live and neutral together to earth

 

[doglog]

but that doesnt PROVE Insulation Resistance is all clear between live and neutral does it..if there was a live/neutral fault I would only find out when energising and BANG..??

 

[peteludman]

lives to earth is all you need for periodic but if its a new instalation L-N should have been tested befor the connection of transformers

 

[electricAl]

Sorry Paul for not offering a solution that doesn`t involve disconnecting the tx, but there`s not one that i can think of.

Assuming this is indeed a new install, you should have first tested all LV conductors upto the disconnected Selv transformers @ 500v, then between individual secondary conductors on the ELV side @ 250v.
Finally, tested between live conductors (connected together) of Selv secondary circuit and those of the LV primary side & any other adjacent LV ccts. This should be done @ 500v.

A bummer i know, but there it is m8

 

[monkeyelectric]

but that doesnt PROVE Insulation Resistance is all clear between live and neutral does it..if there was a live/neutral fault I would only find out when energising and BANG..??

I see what you're saying but tis the only way without disconnecting the transformers

 

[doglog]

Thanks for your help.the installation is indeed new and it was 2nd fixed before I could get to test it..also all the lights have been calked around and decorated so Id better not disturb them to disconnect transformers..
I will test both live and neutral to earth and assume live/neutral to be clear if breaker sets ok..
Many thanks guys

 

[martysparky]

makes you think why didn't they make them with push in connectors to easily disconnect for testing?

 

[bugsy]

Should always do I/R tests before installing l/v s , We always use Wago 3 lever connectors just in case we need to retest.

 

[martysparky]

Should always do I/R tests before installing l/v s , We always use Wago 3 lever connectors just in case we need to retest.

never seen them before. fantastic.

 

[marksparky]

click do a connector now male and female ends with a terminal for the loop in for those of u who wire mains round the lights great for lv downlights