Testing an Extention lead

DaveyD · May 11, 2011

Hi

OK, got an extention lead thats shot (not mine) With only a Fluke 1651 NOT a pat tester I have 96 volts between CPC and phase yet an IR test shows >500 M ohms. ? How would you test?
Kind Regards
David

topquark · May 11, 2011

DaveyD said:
Hi

OK, got an extention lead thats shot (not mine) With only a Fluke 1651 NOT a pat tester I have 96 volts between CPC and phase yet an IR test shows >500 M ohms. ? How would you test?
Kind Regards
David

Err, what do you mean by you have 96V between CPC and phase? Under what circumstances?

DaveyD · May 11, 2011

Thanks for the reply TQ ..Under the circumstance that I have an earth fault that I can only find by reading between phase and cpc when pluged into mains OR using a little plug martindale in tester that I only keep for use as a final functional tester. I cant get a fault by IR tests but they must be a breakdown.

Deleted member 26818 · May 12, 2011

if there's no continuity between the extension lead conductors, then the fault is probably in the installation you are plugging the lead into.
Perhaps there is something else plugged into the circuit that is providing the 96V between line and earth.

DaveyD · May 12, 2011

Hi Spin, no brought home too and tested on our home supply - same problem. Voltage before lead 241 with lead 126 and between cpc and phase around 95. Its not a problem, the lead looks knackered and its not mine. I just thought that a simple IR test would show breakdown. Otherwise how would you tell?
Regards, David

topquark · May 12, 2011

So just by plugging into the mains you are getting a PD between Line/Earth on the lead (with no load) and the socket is fine before hand. Is it moulded at each end?

You'll need to be VERY careful when handling it when plugged in of course

Is it worth spending any time on it, or is this just an education exercise? Check the flex for any external damage first, either brittle outer insulation (sign of over heating) or cuts/nicks. Then it's down to checking the terminations in the plug/socket ends.

DaveyD · May 12, 2011

Thanks again for your reply TQ. Oh yes, purely for educational reasons. I did examine the lead and it has been overloaded at some point in the past. Here is the thing ... customer decided they could not wait for the dishwasher and machine to be connected (im doing a new RFC for the kitchen, new CU and upgrade on the bonding) so ran their old lead from outside the kitchen to these two appliances. I happened to touch the DW and the sink and the potential difference gave me a belt. I know the bonding is good, I know the circuit they ran from is good and tested so after testing all again checked their extention lead and it was shot. (brought home and tested here too - same result) But I'm frustrated that a simple IR test did NOT show a fault 500v gave me >500 Mohms - only the following showed it was faulty:
1. voltage between the lines and CPC
2. Condition of the lead (bumpy)
and 3. a cruddy littly socket tester.

I am going to take the plug and socket off and try direct on the wire when I get back.
Kind Regards, David