testing new lighting cct

[palmerelectrcal]

ive just completed a new installation,,, all ok... except one lighting circuit... an insulation test phase to eth...400+ M/ohms .ok..but there seems to be
a low reistance from n to eth....? 0.79 ohms. theres two way/intermediate & several downlighters....ensuite fans/isolaters.etc...
pulling my not so thick hair out!!!...cpc continuity ok through to end of cct.and all works ok. need experienced advice.regards.andyp

 

[wallyanker]

Have you disconnected all sensitive equipment, eg, neons, fans, lamps??

 

[Octopus]

with a reading that low I'd be looking for fixed equipment still connected and switched on.

 

[telectrix]

IR test should have been done before any loads were connected..

 

[wade88]

IR test should have been done before any loads were connected..

Corrrr hindsight is such a bit*h :banghead:

 

[Richard Burns]

If your reading is in ohms then you have a near short in some wiring; if it is in Mohms then I would be looking for items with circuit boards in them such as the fans, if you have isolators everywhere then test the circuit with these isolators off (assuming they are double pole) and this should narrow down where to look for the problem.

 

[ackbarthestar]

From my experience, the only way you would have got 0.79 Ohms while doing an IR test is if you had switched your instrument range to read continuity.

If you are measuring N-E, then you have either got a dodgy piece of electronics connected or crossed your neutral and cpc somewhere, assuming its not an TN industrial board.