Discuss Fault on socket circuit in the Electrical Forum area at ElectriciansForums.net

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Grant McLaren

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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.
 

Murdoch

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Only proper testing, dead, live, IR can help you

Have you got an earth clamp meter?
 
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Pete999

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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?
 

Murdoch

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Cards on table time - are you the landlord or a spark?
 

Pete999

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In what ?
It comes under "what electrical qualifications do you hold", under that assumption, I would guess he means an electrical NVQ3 Mind you I could say the same only I don't, have an NVQ3 that is.
 

Strima

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My crystal ball is still in for calibration so I can't help...
 
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Grant McLaren

EF Member
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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?
 
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Grant McLaren

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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.
 

Dillb

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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

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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.
 
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Grant McLaren

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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

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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??
 
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Grant McLaren

EF Member
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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

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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?
 
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DPG

Respected Member
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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.
 

Dillb

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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.
Ahh the good old NICEIC says it’s good. Why leave a kitchen on a ring and not other circuits?
 

Murdoch

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Oh my god
 
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