IR Test ? Weird issue N-E only

[Soulsurfer]

Hey all, just doing some tests on a small extension and have a weird issue with IR on lighting circuit, all switches left open as nightmare to strip all lamps, fittings etc.. L&N to CPC not ramping up over 7-15V DC then resetting test !

L-N on 250V or 500V 31-32 Meg
L-E 32.6 Meg
N-E won't go ! Tried all obvious things to remove out of circuit plus new mains smoke detector etc.. but still no good, any ideas ?
Only fed at moment on a B MCB 6A no RCBO etc.. head scratching or feeding something hidden maybe or a fault ?
Thanks.

 

[westward10]

Left all mains on to rest of house as they wouldn't have juice off while in there !
Just pulled related L,N,E from terminals at Cu to test

You should have the cpc connected to the earth bar.

 

[Soulsurfer]

I still don't understand why you have left them open.

I figured in my early testing career that it would save frying any LED downlights or dimmer module etc.. as would take a good while to disconnect all fittings / lamps etc.. straight away. Tested at 100 & 250 V too to save any issues but none would ramp up test voltage to CPC

 

[Soulsurfer]

I still don't understand why you have left them open.

I figured in my early testing career that it would save frying any LED downlights or dimmer module etc.. as would take a good while to disconnect all fittings / lamps etc.. straight away. Tested at 100 & 250 V too to save any issues but none would ramp up test voltage to CPC

You should have the cpc connected to the earth bar.

Always done IR with every conductor out and in croc clips ? NIC assessor said was right way ? Thought would cause parallels if left in Earth bar ! Maybe I've made a fundamental boo boo

 

[westward10]

Won't fry anything and I only ever resort to 250v if I get odd readings to cancel out possible filtered equipment.

 

[Octopus]

RE awkward fittings and dimmers ..... Just fit standard switches and omit light fittings and do continuity and ir tests first ...... Can save hours of hassle

 

[westward10]

I figured in my early testing career that it would save frying any LED downlights or dimmer module etc.. as would take a good while to disconnect all fittings / lamps etc.. straight away. Tested at 100 & 250 V too to save any issues but none would ramp up test voltage to CPC

Always done IR with every conductor out and in croc clips ? NIC assessor said was right way ? Thought would cause parallels if left in Earth bar ! Maybe I've made a fundamental boo boo

Never isolate the cpc from the main mass of earth.

 

[buzzlightyear]

Thanks Lee, I'll try next time when customers not being a pita !

was the customer biting on your ear!

 

[Soulsurfer]

RE awkward fittings and dimmers ..... Just fit standard switches and omit light fittings and do continuity and ir tests first ...... Can save hours of hassle

True, thanks, just builder wanted lights in and on during the ongoing works tiling etc.. so been on / off throughout job !

 

[Soulsurfer]

was the customer biting on your ear!

Bit of a hitler the wife there !

 

[Octopus]

True, thanks, just builder wanted lights in and on during the ongoing works tiling etc.. so been on / off throughout job !

I have an assortment of standard switches for such situations and a few pendants too ........

 

[Risteard]

Just pulled related L,N,E from terminals at Cu to test

The 17th Edition requires the cpc to be connected to the Earthing arrangement before conducting insulation resistance tests - therefore the cpc should NOT be removed from the Earth bar. Otherwise a fault to Earth that isn't a fault to the cpc won't be detected.

 

[westward10]

I suggest you retest with the cpc connected to the earth bar, close all switches and retest, use 250v if you are concerned.

 

[Soulsurfer]

The 17th Edition requires the cpc to be connected to the Earthing arrangement before conducting insulation resistance tests - therefore the cpc should NOT be removed from the Earth bar. Otherwise a fault to Earth that isn't a fault to the cpc won't be detected.

Thanks

 

[Soulsurfer]

I suggest you retest with the cpc connected to the earth bar, close all switches and retest, use 250v if you are concerned.

Will do & with main switch open too !
& if readings good I'll bang the 500 on, thank you, was thinking it was maybe N-E fault or something!

 

[westward10]

If the neutral is disconnected you don't need the main switch off but with your tester backing off with the L/N to earth test maybe you have a fault. I don't use an mft to understand their quirks, life is too short