Low Insulation Test Results

[markharris]

Hello guys,
Got my fisrt NICEIC assessment on Thursday, and to my horror after I fitted an outdoor socket as my minor job, my insulation test results were terrible.
It was a spur off a kitchen ring, so when I dead tested I unplugged all the loads which were on grid switches but left the grid switches on, all sockets had their loads disconnected, washing machine,fridge,extractor fan, dishwasher all unplugged, the only load I didn't remove was the ignitor for the gas hob,I understand that if there are any loads that you cannot remove then you should not test between live conductors as you will get poor readings, but will a hob ignitor really give me 0.05M?
My results Line/Neutral-0.05M,Line/Earth-1.94M,Neutral/Earth-1.95M

Polarity was fine, no voltage drop, Earth continuity fine, Zs of 0.25 and RCD operated within 200ms.
I am worrying about what assessor will say, but if I have identified the problem and record it as such on the minor electrical works certificate, as needing further investigation will that be OK?

I am doing my test, by two probe method,with the MCB off,I am probing between MCB'S and the earth and neutral bars, without disconnecting conductors.
Advice would be greatly appreciated.

 

[Des 56]

Reading through your question again
The results you gave,was this for the whole of the installation ?

If the whole installation was tested then the results being below 2 meg ohms,not good
In this case you need to test each circuit individally to find out if this is a combination of circuits in parallel bringing the reading down,or one circuit being the culprit

A minimum reading of 1 meg is required for each circuit

If it was just the kitchen circuit,then without dis connecting the neutral,you will be reading the whole installation value of neutral-earth not just your circuit

To insulation test between live-neutral you must dis connect all loads

Try dis connecting all loads to the circuit and testing with the circuit isolated (live + neutral)
If this cant be done,connect live-neutral together and test to earth to obtain the circuit value,however, the insulation test is an whole installation test,so if possible,test the whole

 

[markharris]

Many thanks,
I am just insulation testing the kitchen ring,with the MCB off, and all conductors still connected in their respective bars and MCB. When you say test with the circuit isolated, do you mean disconnect the live, neutral and cpc conductors and then do the insulation test between live/neutral, live/earth, earth/neutral?

 

[J@mes]

I'd disconnect the neutral at the bar to make sure that you weren't getting false readings due to it being connected to earth some point back towards the DNO's end.

 

[mnmwill]

Any neons left in circuit cos they screw yr readings up?