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Hi all
I have just moved in and am in the process of adding some sockets. Am I right in saying that I can add to the circuit regardless of which type of circuit it is as the MCB is a 20a, obviously as long as I'm using 2.5mm t+e not speaker wire etc. I get the issues with RFC where 32a fuse meets a 26a cable but wanted to check if there were any other issues I wasn't aware of. Hope this makes sense and thanks in advance for your time.
 
Yes, you can add to the circuit.
You do need to ensure the Zs for the extended part is low enough for the MCB to operate in the event of a fault.
Also, assuming this is a socket circuit, the extra sockets and possibly the cabling will need RCD protection.
 
I get the issues with RFC where 32a fuse meets a 26a cable
What you will find with a ring final circuit is that standard 2.5mm t&e is not rated to 32A as the idea of a ring is that each cable carries half the current, so no cable will ever be carrying 32A
 
And remember you can only ever have one unfused spur off a ring final circuit
And remember you can only ever have one unfused spur off a ring final circuit
Think you may need to elaborate on that statement Barnaby. Refer to amendment 15 BS7671, the statement you made eludes to only 1 nonfused spur from a RFC.
 
Unfused spurs from a ring wired in the same cable as the ring are allowed to run one socket (single or double) or one fused connection unit (FCU). Is that better?? what were you thinking Pete999?
 
Unfused spurs from a ring wired in the same cable as the ring are allowed to run one socket (single or double) or one fused connection unit (FCU). Is that better?? what were you thinking Pete999?
Like I said Barnaby, reading your post you say you can only have 1 nonfused spur from a RFC, when in reality you can take spurs from any where on a RFC, from an existing socket, a JB or the point of connection at the CU, I'm not sure of the exact wording as I don't have BS7671 to hand, but somewhere if my memory is correct the number of non fused spurs must exceed the number of socket outlets on the RFC, nt including spurs, so as an example say you have 10 SOs wired as a RFC then the max number of spurs is 10 SOs, as I said I don't have a copy of the BS so unable to check but I think I'm correct, to be sure you nee to check Appendix 15 regulation 433.1 Appendix 15 is an informative document.
 
There’s no limit Pete.
In fact in the past, some rings were wired with all sockets as spurs for some unknown reason.
I generally refer to these as spider rings.
Bloody nightmare, as you can’t spur off from any of the sockets.
 
Since 1970 it is permitted to have more spurs than sockets on the ring, but it is considered poor practice by many electricians to have too many unfused spurs in a new installation (some think they are bad practice in all cases).
In my experience I have found it a lot more difficult to test rings with lots of spurs if you have insulation faults, for example, as there are connections outside of the basic ring which have to be found etc
 
Since 1970 it is permitted to have more spurs than sockets on the ring, but it is considered poor practice by many electricians to have too many unfused spurs in a new installation (some think they are bad practice in all cases).
In my experience I have found it a lot more difficult to test rings with lots of spurs if you have insulation faults, for example, as there are connections outside of the basic ring which have to be found etc
Thanks for that info Guys, how things change?
 
Yes ok - sorry not to make myself clear. Yes spinlondon you are right. That is what i was trying to say but wasn't very clear about it I admit.
No need to be sorry mate, the regs don't make it easy to explain things , Quite sure you knew what you were on about, my concerns were for the OP as there is no information on his skill set,
 
Of course with older properties, none of the JBs will be maintenance free and will now be covered over with laminate flooring or fitted carpets.
 
Of course with older properties, none of the JBs will be maintenance free and will now be covered over with laminate flooring or fitted carpets.
Of course Spin.
 
Thanks for your input everyone. The circuit is currently on a 20a MCB so it may well be a radial anyway though I wanted to assume RFC and check accordingly. The sockets I'm adding are replacing single surface mounted sockets which were currently running everything from extension leads. I took one cable from this into the 1st new socket then from the last new socket back into the 2nd original cable. The existing socket box contained the wagos I used to connect the two cables to my additional ones. One of these original sockets was served by 1 cable and in this case I have replaced this with a 13a fcu before running the spurred sockets. I might add this is all a temporary measure until decorating at which point I'll get a proper sparks in to do it, so there's no issue of van loads of 3k heaters being used, it was more to do what was being done already through 6 gang extension cables and ropy bakelite socket. I am unable to test zes however so if this is necessary any idea how much id be looking to get someone to do this in the London area?
Thanks again.
 
Paul
Hi and Welcome, honestly to do this work safely, you need the services of a competent Electrician, if you were closer I would help but London??
 
Paul
Hi and Welcome, honestly to do this work safely, you need the services of a competent Electrician, if you were closer I would help but London??
Post code and I'll check distance please, and let you know.
 
Thànks all. I have someone through a friend who is local so no worries I'll give them a shout, I was just wondering if I was talking 10s hundreds etc. Thanks all for your time in answering
 

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