Fused Spurs & Sockets


Postby cookie85 » Tue Jun 19, 2007 12:47 pm

Hi,

Everywhere i look i seem to read a different answer, can somebody please tell me how many fused spurs can you run of a typical 30 amp ringmain? Is it 2?, or as long as you fuse them with a 13amp fuse you can run up to 3 or 4?

Also the number of additional sockets you can add to a ring main from a fused spur, ive heard theres no limit, but surely there must be if you can only run 2 spurs from a ringmain?

Ive got a single socket which i would like to increase to a 2gang socket. The single will only have 3 wires running to it, is this correct? If so how do i wire up the additional socket?

Look forward to your responses.
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Postby sparx » Tue Jun 19, 2007 4:20 pm

Hi Cookie, I think the confusion comes from the terminology people use.
EG 'Wires' means diff. things to diff. folks. a 'cable' consists of 2 or more 'cores' which contain 'conductors', N.B. no mention of 'wires'.
'Wire' is a very old, much abused term & could be the stuff holding up your garden fence, it has no meaning in modern electrical work. We used to refer to earth wire but now called 'circuit protective conductor' or CPC for short. Not meaning to be 'picky' but if everyone used correct terms. less mistaken meanings.
As for your ?s,
1) do you mean spurs as in a cable running to a socket outlet from a socket on the ring (or from a junction box on the ring) in which case answer is 1 single or double outlet only.
2) If you connect a 'Fused-connection-unit' (previously known as a fused spur) to a ring circuit you can indeed run any number of socket outlets from it because the total load you can apply to it is limited by the 13A fuse in the FCU, no different to a multi-way extension lead.
3)single & double (1 & 2 gang ) sockets only have 3 terminals so connect the same way, they are internally linked.
hope this is what you needed to know, regards SPARX
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Postby cookie85 » Tue Jun 19, 2007 6:59 pm

Sorry about my terminology, i am from a mechanical background.
So can i just clarify a few points:
(I meant from a socket not a junction box)

From point 1:
So directly from a ring main you can only spur off to one double or single socket. This will be wired with a 3 core flex cable, from the ring main circuit socket to the stand alone double or single circuit? Is that right?

From point 2:
But using a spur to a 13amp FCU you can run a number of sockets of this as it fused to worse case?

From point 3:
I assumed a double had effectively 6 wires to it, as it was a ring main and looped to the next socket. Is this wrong, and your sayin whether its double or single it still has 3 wires.

If thats the case, why do most electrical books say that if the double/single socket only has 3 wires going to it, you cannot spur off this. If this was the case surely you couldnt spur of any socket?

Look forward to your response. Cookie
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Postby sparx » Wed Jun 20, 2007 2:20 pm

Hi Cookie,
1) apart from the use of 'flex' as all fixed wiring must use cable, IE twin & earth with green/yellow sleeving over bare cpc.
2) Yep!
3)No i'm saying that a socket on a ring will have 2 sets of three cores but the socket will only have 1 set of 3 connection terminals ie 2 conductors in each term.
regards B.W. SPARX
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