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Grant McLaren

I am puzzling over an intermittent fault on a ground floor/kitchen socket circuit. Initially it seemed as soon as the oven switched on the RCD would trip. However, after unplugging the oven, I used a socket tester on other sockets, which would sometimes trip the RCD. It's pretty random, sometimes it will trip as soon as you plug something in, other times not. Zs reading were fine. The ring main has been broken, although the earths are still continuous. From what I saw, the socket circuit has not been done well.

When I left the property yesterday everything was on, but I'm waiting for a call from tenant to say it's tripped again.

Any thoughts on what it could be and why it has suddenly started now?

Regards.
 
So you have used a socket tester for fault finding and left a RFC with no continuity on it?
Looks that way Mate, makes you wonder sometimes. OP just be clear on this point did you do any IR testing, R1+R2 testing how did you conclude that the Zs is compliant?
 
Lol you guys are funny.

Used installation tester for testing. My point about the socket tester was that it and other nearby appliances, i.e., router or toaster would trip the RCD when I plugged it, but only occasionally.

The question is what could cause this and why? If there was a break down in insulation between, say earth and neutral (which is possible, since a continuity test between neutral and earth on one end of the broken ring at the CU gave me around 13 ohms, why wouldn't the RCD trip all the time and instantly?
 
Ring Final Circuit, Ring Main is no longer used, it's old hat, it is no more, Ring Main is Dead, RIP Ring Main, with your quals you should,or ought to be aware of that fact.
I do know what ring final circuit is, I just haven't heard it referred to as RFC.

I didn't know that ring mains weren't used anymore, although I independently stopped using rings ages ago. Whenever, I encounter an old ring, I assume it is broken and downgrade to 20amp.
 
You say you have continuity beteeen E-N, that may not trip if the current still finds a return path on the neutral which wouldn’t trip the RCD
 
You say you have continuity beteeen E-N, that may not trip if the current still finds a return path on the neutral which wouldn’t trip the RCD
I didn't know that ring mains weren't used anymore, although I independently stopped using rings ages ago. Whenever, I encounter an old ring, I assume it is broken and downgrade to 20amp.

Why do you assume that? Testing the circuit correctly will verify wether it’s good for continued use, not guess work on your part.
 
Wha tests did you carry out and what were the results from then tests?
Zs 0.9ohm was about this highest reading.
tested continuity between line, neutral and earth, I guess this is a form of IR test.
And opened up most of the sockets for a visual inspection. Apart from a few loosely tightened terminals, which are now tight, all seems fine.
RCD is working as it should.
Didn't do a R1+R2 test (although I should have), but let's assume there is something wrong here, why would it only now start presenting problems, when nothing in the installation has changed.

One final thing, I'm anticipating returning the property to get this sorted, but I thought first I'd get some thoughts from some friendly sparks. At least I found some sparks.
 
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