Problem with IR test result on RFC's

bobodhi · Mar 30, 2010

Hi, I've been testing my house and few others in the area as a way of gaining experience.
I'm mostly getting satisfactory results expect for insulation resistance testing on the ring circuits. I follow procedure and remove all plugs from sockets and turn them on but when I do the test I get a zero reading both on live/neutral and live/earth.
This problem is appearing in several houses not just mine so I'm obviously missing something, probably 'bleedin obvious', and I'll kick myself.
Any ideas?
Regards, Kevin

pevvers · Mar 30, 2010

What happens if you open the main switch, leave all MCB's on and fuses in place and test to protective earth with line and neutral connected together?

bobodhi · Mar 30, 2010

Hi, thanks, quick answer, not quite sure what your suggesting here, are we talking about establishing some continuity or putting a voltage through to see what happens?

pevvers · Mar 30, 2010

Just wanted to make sure that you had opened the main switch before testing. Test method 2 from GN3 is always the best way to test on periodics...

Deleted member 9648 · Mar 30, 2010

Sounds like there is still a load connected somewhere which would explain the L-N, and have you disconnected the neutrals at the DB as if not you would get a L-E reading through a connected load and the still connected neutrals.

bobodhi · Mar 30, 2010

Mmmm... yes, I think you're both on the right track. I'm using test method 1 and I suspect there is a load somewhere that is giving me the zero reading. I've read up again on GN 3 method 2 and will give that a go tomorrow.
Regards and thanks for the input to all. Kevin

Spudnik · Mar 30, 2010

Cant really improve on what the lads have said already, however, you could always do N-E and that should read clear.

Johno · Mar 31, 2010

its probably something still plugged in ( get out before its too late) it could be a washer, dryer, integrated appliance, cooker hood, whatever. In most houses there is a 6ft cabinet with tv, dvd, wii, ps3, cd player, mp3, etc which weighs 10 tonne and cannot be moved!!

bobodhi · Mar 31, 2010

Hi, thanks, I'm pretty sure that it's something to do with the heating setup in the houses I'm testing in, as I've definitely removed everything from all the sockets and outlets that I can find including all the spurs.
Regards, Kevin