Fault on socket circuit

[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.

 

[Dillb]

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

 

[Dillb]

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.

 

[Deleted account]

What's an installation tester?

 

[Deleted account]

Duplicated post again.

 

[Grant McLaren]

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.

 

[DPG]

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.

He doesn't mean the ring form isn't used any more. He means the terminology for a domestic ring circuit is 'RFC' and has been for some time.

Surely you don't just downgrade every ring circuit you come across as a matter of course??

 

[DPG]

Zs 0.9ohm was about this highest reading.
tested continuity between line, neutral and earth, I guess this is a form of IR test.

No it isn't.

 

[Grant McLaren]

What's an installation tester?

Installation tester: a multifunction tester to keep you safe | Fluke - http://www.fluke.com/fluke/uken/products/installation-testers

 

[Dillb]

RCD is working as it should.

What did you do to prove this?

 

[Dillb]

Installation tester: a multifunction tester to keep you safe | Fluke - http://www.fluke.com/fluke/uken/products/installation-testers

What tester did you use to carry out the testing?

 

[Spoon]

Whenever, I encounter an old ring, I assume it is broken and downgrade to 20amp.

I really, really hope that you are being sarcastic with this comment....

 

[Grant McLaren]

He doesn't mean the ring form isn't used any more. He means the terminology for a domestic ring circuit is 'RFC' and has been for some time.

Surely you don't just downgrade every ring circuit you come across as a matter of course??

If I do work on it I do, with the possible exception of a kitchen or utilities circuit, since they might need the extra juice. NICEIC assessor thought it was a good idea. Besides, I thought the UK was moving away from rings, since they were originally used for old school heating systems.

 

[Pete999]

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.

Why?

 

[Grant McLaren]

I really, really hope that you are being sarcastic with this comment....

no, why wouldn't you do it?

 

[DPG]

If I do work on it I do, with the possible exception of a kitchen or utilities circuit, since they might need the extra juice. NICEIC assessor thought it was a good idea. Besides, I thought the UK was moving away from rings, since they were originally used for old school heating systems.

Each to their own.
Not originally for heating systems no - just for general domestic use. Copper shortages and all that.