I've put a simple ring from the CU in the garage using all new 2.5mm cable etc. consisting of 2 double sockets before returning to the CU. The RCD keeps tripping out on load, although the individual 16A circuit breaker doesn't trip. Everything is perfectly okay without load. I've knocked off all the other CB's, this doesn't help. Because it's such a simple addition I cant think of what the problem is. All I can do is to move the supply over to the non RCD protected side of the split CU, no problems on that side when connected. Any ideas?
new ring, RCD tripping
- Thread starter muffindell
- Start date
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Most likely it is wired wrongly, or wires have been damaged when fixing the sockets. Less likely is cable damage or defects.
A ring with 2 sockets is pointless, so is a 16A ring, and the work is notifiable, so as usual, the lawbreaking continues.
A ring with 2 sockets is pointless, so is a 16A ring, and the work is notifiable, so as usual, the lawbreaking continues.
Yep it'll be a neutral wire in the wrong neutral bar.
As has already been said, a radial circuit would be much more apropriate for this installation, and as it stands, a 16A ring does not comply with the wiring regulations.
As has already been said, a radial circuit would be much more apropriate for this installation, and as it stands, a 16A ring does not comply with the wiring regulations.
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Aside from the fact that you have broken the law and implemented a ring final circuit in breach of the regulations, you should be able to tell what the problem is by re-examining your test results.
If you publish here your end to end results r1, r2 and rn - your figure of eight results, your insulation resistance figures and your ELI - we might be able to give you some advice.
Hang on guys 
, no one said that the work wont be signed off and certified. No one said that the CB wont be changed for a 32A version or another 4 sockets and one fused spur are to be added to the circuit. It was a straight forward question but can now see where you're coming from with the neutral. It was about 30years ago that I qualified C&G sparky but never used it after I changed industry to something totally different at the same time.
Anyway thanks for you help, I'll swap over the cablework and test the theory If that works then I will get it certified
, no one said that the work wont be signed off and certified. No one said that the CB wont be changed for a 32A version or another 4 sockets and one fused spur are to be added to the circuit. It was a straight forward question but can now see where you're coming from with the neutral. It was about 30years ago that I qualified C&G sparky but never used it after I changed industry to something totally different at the same time.Anyway thanks for you help, I'll swap over the cablework and test the theory
If that works then I will get it certified- Joined
- 27 Sep 2004
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433.1.5
It cannot be signed off and certifiied because according to your OP the electrician has not been part of the process - this is abundently clear because you have gone for a ring final circuit when given your current and proposed set up a 20Amp (2.5mm T&E cable) RCD protected (unless visibily clipped to the wall) radial final circuit would have been more than adequate for your needs.Hang on guys
Anyway thanks for you help, I'll swap over the cablework and test the theory
It doesn't work like that, you can't do the work then get someone to certify it for you.
The old chestnut again. The maximum over current protection for a ring final using 2.5 mm is determined to be 32 amps.
There is nothing that states the over current must be 30 or 32 amp and that anything less is a breach of the regulations.
There is nothing that states the over current must be 30 or 32 amp and that anything less is a breach of the regulations.
Where does the word maximum appear in regulation 433.1.5?
There can be no regulation which says fitting a lower rated CPD is banned.
This would be the equivalent of saying 'Thou shalt not fit greater protection'.
This would be the equivalent of saying 'Thou shalt not fit greater protection'.
The regulation says that accesories may be supplied through a RFC protected by a 30A or 32A OCPD.
That is it. It doesn't say supplied through a RFC protected by a 32A or lower rated device. If you want to use a RFC to supply accesories then a 30A or a 32A device are the only sizes recognised by BS7671.
If you want to use a lower rated OCPD, then there would be no point in installing a RFC in the first place so a radial should be used.
That is it. It doesn't say supplied through a RFC protected by a 32A or lower rated device. If you want to use a RFC to supply accesories then a 30A or a 32A device are the only sizes recognised by BS7671.
If you want to use a lower rated OCPD, then there would be no point in installing a RFC in the first place so a radial should be used.
Agreed.
433.1.5 and appendix 15 are for 'bog standard RFCs' without thinking.
However, this does not preclude other configurations which comply with the regulations.
Look at it another way - you are saying that if a 16A MCB is fitted then the return leg MUST be removed even though it is not doing any harm and is the equivalent (approximately) of using 5mm² cable.
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