Spures - so what would you do?

NoSparks · Oct 4, 2009

In a building extension involving an extended kitchen I have found that two of the three double sockets are on one spur, and the other on another spur, but who knows if the two spures don't join before the ring! The origen of the spur is burried in the wall or floor and cannot be found.

Short of re-wireing the kitchen, what do I do?

I could put an FCU on each spur, but if they did join togther that would give me 2 FCUs on a single spur - outside regs.

I could put a 20A breaker on the ring, but then the 20A circuit would be supplying about 90 Sq mters - outside regs.

Any other suggestions?

(The likely use of the two double sockets would be kettle, microwave, slow boiler, etc so only 1 hefty load. The other socket is exclusive to the washing machine and fridge/freezer.

The other two rooms served by the ring might have televisions, irons, but not much more, and the house is gas central heating.)

Mac · Oct 4, 2009

Rings should be on a 32A breaker.Have you looked at appendix 15 of the regs.

NoSparks · Oct 5, 2009

Actually Mac, App 15 refers back to reg 433.1.5 which simply states that a ring wired with 2.5mm cable and with a 30/32A protective device satisfies the requirements of 433.1.1 . Reg 433.1.1 requires simply that the protective device must not exceed the lowest of the current carring capacities of the of any of the conductors. Thus, although not normal, a ring run in 2.5 mm may be protected by any device upto 32A.

In my case the unfused spurs form the lowest of the current carring capacities and therefore. assuming the circuits run through the walls/floors and are not insulated their maximum capacity is 20A.

peteludman · Oct 5, 2009

to save a kitchen rewire can you put the spured sockets on 4mm instead , i expect that it is tiled

NoSparks · Oct 7, 2009

Pete, Not sure how you change the wire without rewireing?

Mark.W · Oct 7, 2009

Put an FCU on the "spur" that has the 2 sockets....

sivoodoo · Oct 7, 2009

Which reg states you cant have two spurs on a radial?
Thank you

electricAl · Oct 7, 2009

sivoodoo said:
Which reg states you cant have two spurs on a radial?
Thank you

There isn`t any. No problem with spurring off radials. But that isn`t applicable here.
NoSparks` problem is he can`t be sure that the ring isn`t feeding a spur off a spur (unfused) which may exceed the ccc (he doesn`t say, but i think we`re to assume both are in 2.5mm) - from a possible intersection, to the unknown point it reaches the spur.
I deleted my original reply after re-reading his posting (properly this time

)

Yup, tough one.

I`m guessing there isn`t a logical place to split the ring between the spurring off points (otherwise you`d have tried it, if only as a diagnostic measure) & so if they really won`t allow any dismantling, then i can`t see a better way than an FCU supplying each spur. You`d atleast be guarding against inadaquate protection of any vulnerable section and in the circumstances, could be forgiven for the heinous crime of over-fusing

Sorry i can`t come up with anything more useful...

NoSparks · Oct 8, 2009

Yes, just to re-itterate, there is the possibility that the second spur comes off the first spur, giving a net total of 3 twins of a single spur with no way of identifying the origin of the spures.

Update though.

I went back the following day and just to compound the issue found a fourth twin soket hiding beneth a worktop and IT was wired with 1mm cable

so now we have two twin scockets on each spur (which may join togther before joining the ring). HOWEVER

, the owner has agreed to take up the floorboards above the kitchen where the spures might originate, and if they do I can then fuse them. ... but not until December!

electricAl · Oct 8, 2009

This December or the following one?

If they leave it as long as 2010, it may simply be too late - one of those cables may well overheat.

However, this December`s only 8 weeks away - the cable`s hardly likely to overcook before then is it

"It`s been like that for 27 years & we`ve never smelt burning, have we Eric? If you just fit those nice shiny brass switches for now, we`ll have a think about what you said about needing the lights earthing..."