Spur from a spur. Regulations, problems and solutions - discuss.

[ProDave]

Here's todays job I went to look at. Newly re fitted utility room, new laminate flooring (apparently laid over quarry tiles) newly tiled walls, new units fitted, and no socket for the tumble dryer (why don't people plan ahead headbang )

So how to get a socket for the tumble dryer? Ah spur from the washing machine socket 2 metres along the wall and run in conduit behind units.

But the washing machine (double) socket is already a spur.

Can't get another feed from anywhere else, or upgrade the spur to a ring without trashing the finishes already done.

So lets think about this and discuss it.

IF the existing double socket was close enough to reach both appliances, then both plugged into one double socket would be okay. Maximum load would be 26A, just within cable ratings, and a single spur (double) socket is allowed under regs.

But I don't think the socket could be moved to a suitable location, without one or other appliance having a longer than normal mains lead fitted.

So what about change existing double spur to a single, and spur another single from it. Oh dear, not allowed by regs, BUT the same current would flow, the feed cable would be under no more load than if both sockets on the double are used, so WHY is it not allowed by regs?

The only "solution" I can see is as above but with each 13A single socket fed from a 13A FCU. That guarantees no overload of the feeding cable (and covers the situation of someone changing a single for a double), but STILL you have a spur on spur situation to feed the two FCU's.

Can anyone find a legal solution? or (as I suspect will happen) the customer will just use an extension lead under the units to plug the tumble dryer into the existing double socket, which can't be "safer" than providing a propper socket can it?

 

[Nicky Tesla]

I wouldnot have a problem with changing the socket to a single then feeding through the wall to another single. If anyone then changes either of these sockets to double later, this is not your problem. You could if you want change the double socket back box to a twin single back box accommodating i single socket and one fused spur feeding the socket on the utility. Make sure also that the kitchen socket is not already a spur off a spur.

There is no problem having a spur off a spur as long as the design current is less than the current rating of the cable used.

 

[kme]

Nicky may not "have a problem" with 2 single sockets; but the regs do, as you`ve succinctly noted.

The other issue you have is this (which has also been discussed before) - MOST double sockets are rated to carry 20A; NOT 26.

Can the ring be de-rated to a radial; or even split and converted to 2 x 20A radials? If the customer intends to have W/MC & dryer on together, this could be an issue.

Can you take a cable externally; i.e. in conduit etc. , if this wall is external?

You DO have the option of forging ahead, and writing out a deviation; but, in this case I would be loath to sign my name to it.

KME

 

[Apache]

The only "solution" I can see is as above but with each 13A single socket fed from a 13A FCU. That guarantees no overload of the feeding cable (and covers the situation of someone changing a single for a double), but STILL you have a spur on spur situation to feed the two FCU's.

It has been said on here before that you can spur as much as you like IF it's fused. Do this and it will be fine.

 

[ProDave]

It has been said on here before that you can spur as much as you like IF it's fused. Do this and it will be fine.

Yes, but that would mean a 13A FCU feeding BOTH sockets, no good when both appliances are turned on together. As already noted, feeding each socket on it's own FCU still has a spur on spur situation so no good.

Outside cable not possible. Where the tumble dryer is backs onto a conservatory, and of course not even a close by socket in the conservatory.

I really can't see a solution, so as I say, I suspect the customer will just use an extension lead for the dryer.

 

[Nicky Tesla]

A double socket or two singles are capable of drawing the same amount of current. Nobody has a problem with having a double socket as a spur, even though this would be capable of drawing more than 20A as KME has said. So two singles for me. Stop finding reasons to complicate matters. Dont be like some on here and get yourself tangled up in the meaning of words.

When something is rated at a particular current rating, it means for eg at 20A rating that cable can take 20A constantly for hours on end, but your sockets will not have to do that.

Let common sense show you the way.

 

[Nicky Tesla]

Yes, but that would mean a 13A FCU feeding BOTH sockets, no good when both appliances are turned on together. As already noted, feeding each socket on it's own FCU still has a spur on spur situation so no good.Outside cable not possible. Where the tumble dryer is backs onto a conservatory, and of course not even a close by socket in the conservatory.

I really can't see a solution, so as I say, I suspect the customer will just use an extension lead for the dryer.

I being a customer would not be impressed

 

[Lee321]

you'll have to change the double socket for a 26a rated one. not possible me thinks or change to 2 singles . still not complying tho poss?

you have to remember in socket design we make allowances but if you know what equipment and ratings will be plugged you need to account for them differently

 

[Evans Electric]

I had one similar with a utility room , almost impossible to get a new supply there without great damage to new decor etc. There was , however , a spur from the ring in there so fitted a 1 way C/U with a 20 A MCB . This feeds a Wash M/C , a Drier and two freezers .

Not the best but it works , cable can't be overloaded.

 

[Nicky Tesla]

[quote name='Lee

 

[Lee321]

A 26A rated one??? wot u on about???Wot would you do with a 4mm radial with X amount of sockets on it??? :red card

:^O

the actual socket nicky most are only rated to 13a

but ref i haven't had my first yellow card yet :_|

 

[betty swollocks]

why not extend the mains cable from the appliance to the socket?

 

[wozz]

i thought all DSSO were rated to 13A??

MK do say theirs are stable at 20A but they are not rated to this.

or have i misunderstood what everyone is getting at?

 

[Lee321]

why not extend the mains cable from the appliance to the socket?

because of plugging in 2 13a appliances to a 13A rated dso

 

[Nicky Tesla]

This has been discussed before. Someone rang up the Manufacturers and they said they know it says 13A on them but they built to 20A rating to the same spec as the minimum ring rating.

Lots of you keep complaining about rings, but would the sockets have to be upgraded as the first one would take all the current? No is the answer! cos of diversity. As ive already said when something is rated at a particular current it means it can take that current all day long. On a socket circuit this will not happen.

Has anybody got any technical cable British Standard stuff so we can see what the actual rating parameters are when grading.

 

[Badger]

[quote name='Lee

 

[Badger]

ok then if they are built to 20 amp rating then why have i found and had to replce burnt out sockets? :Salute ray

 

[Lee321]

but nicky we designing socket circuits we normally don't know what is going to get plugged in and it is assumed i guess that 2 13a appliances will not get plugged into a dso? but when you KNOW then you should design accordingly

?

 

[Lee321]

love you badger ROTFWL

 

[betty swollocks]

ive seen countless single fused spurs supplying washing machine and tumble dryer, never seen a domestic dryer or washer coming even close to using 13A, more like 6/7A

same principle would go for a double socket in a kitchen suddenly home owner decides to move things round and plugs in kettle 13A and toaster 13A,

whats the difference?