Unusual earth fault

[Marmalade]

Morning all,
Asked to replace an old weatherproof socket on a house which the property owner uses for his fish pond, plugged in my socket and see prior to starting the job, earth fault.
Checked cables in socket line to neutral 230v, line to cpc not 230v.
Socket feed from a fcu in the property this tested out all ok L to N 230v L to cpc 230v.
Carried out a continuity test on the cpc to the socket this was ok.
Replaced the cable to the socket and now everything tests ok.
I haven't come across this fault before.

 

[Murdoch]

Socket and see testers should be thrown in the bin

What tester did you use to confirm continuity?

 

[binky]

I suspect corrosion on terminals maybe the issue, or within the socket itself, or it was poorly terminated in the frst place. Did the socket have a small drain hole, lots don't and this can lead to condensation in the socket box.

 

[Geoff1946]

Socket and see testers should be thrown in the bin

That's a bit harsh. Obviously not a substitute for proper testing but certainly better than no testing at all.

 

[Barx]

What did you use to test continuity? if it was just some buzzer probes, they will read up to quite a high resistance. So my money would in on a high resistance joint/connection maybe due to corrosion build up.

 

[Marmalade]

Socket and see testers should be thrown in the bin

What tester did you use to confirm continuity?

My fluke multimeter

 

[Marmalade]

I suspect corrosion on terminals maybe the issue, or within the socket itself, or it was poorly terminated in the frst place. Did the socket have a small drain hole, lots don't and this can lead to condensation in the socket box.

I tested the cable itself not at the terminals

 

[kerching]

So,L-N 230
L-CPC NOT 230.....so,what was it ? 229; 200,3???
Insulation test results?
Loop,test results

Nowhere near enough info, and a multimeter is not really a suitable tester

What was the original fault reported? Dodgy/broken socket?

 

[mort2376]

As others have said, corrosion on terminals or in old socket.

It could have been as simple as earth sleeving in terminal.

You tested the cable and proved it was OK, but changed it anyway. A sensible precaution as in your head you know everything is right.

Sometimes you never find the answer it's like when you do an eicr and despite everything being unplugged you get a low IR reading, which by rights should trip the mcb or rcbo, but the circuit works fine.

Only the ghosts in the machines know the full story !

 

[kerching]

Why did the customer want the socket changing?