115V Stops Megger Testing Zs

[paulcopeman]

Hi.

I have been asked by a colleague that was carrying out a Zs on a lighting CCT what could be the cause of his megger not carrying out the test due to it only picking up 115v between phase and earth. He was doing 2 wire lo current loop test but meter just read 115v and bleeped apparently. I'll have to go and look tomorrow after I've finished my jobs but if I can point him in the right direction then maybe I won't have to go there.

I told him to go to board and link out phase and CPC for that CCT and do r1 +r2 but he hasn't got back to me today so I don't know how he got on.

 

[Adrian]

Dimmer switch fitted by any chance

 

[steptoe]

Bad joint? 

 

[Steve3948]

+1 on the Dimmer, did he test at the light by any chance.

 

[ProDave]

Floating earth?

 

[kerching]

Has 'he' managed to get something else in series with it, probably not

 

[paulcopeman]

Just finished my dinner. Thanks for your replies. I hadn't thought of dimmer switch. Yes it was taken at pendant.

If there was a floating earth then surely doing a two lead test (phase and CPC connected only) wouldn't have shown any voltage at all. My colleague got 115v apparently.

 

[ProDave]

I hate to say it, but this shows how someone has "learned" to do the tests by placing probe A here and Probe B there, pressing a button and record the result. They probably have little understanding how the circuit really works and what they are really testing.

Did he repeat the test L-N? did he get the same result?

 

[paulcopeman]

Sooty I'm fixing a fault on my van now. Busy life. I'm not sure what he has done . I'll have to find out tommorow.

More work for me.

Thanks for all your replies.

 

[Murdoch]

What did he get L-N?

 

[larbec]

Have you checked all your grounds