Spur

[AndyH]

I\\\'m considering adding a spur from an existing socket on my ring main. Once I have done this is it possible to run the spur cable into a junction box thus giving me the option of adding more sockets?

 

[Big_Spark]

Whilst in theory you can do this, in reality you should not run more than one socket or outlet from any given spur.

So the simple answer is no if you want to comply with the regulations.

 

[ban-all-sheds]

If you use an FCU with a 13A fuse in it then you can have as many sockets as you like.

It may offend FWL's sense of elegance, and NICEIC may harrumph and mutter about "best practice", but it is NOT dangerous and it DOES NOT contravene the regulations.

But if you don't use an FCU then you must not have more than 1 socket (single or double) on the spur.

 

[AndyH]

Thanks for the replies.

Ban-all-sheds, just to clarify, are you saying I should replace the existing socket with the FCU and spur from that?

 

[BR]

This is what Ban.... is referring to.

Although it could be fitted in place of the existing socket, it is possibly more appropriate to fit it elsewhere. e.g alongside you new socket(s)

 

[Big_Spark]

If you use an FCU with a 13A fuse in it then you can have as many sockets as you like.

It may offend FWL's sense of elegance, and NICEIC may harrumph and mutter about "best practice", but it is NOT dangerous and it DOES NOT contravene the regulations.

But if you don't use an FCU then you must not have more than 1 socket (single or double) on the spur.

What does compliance have to do with my sense of elegence, perhaps you should use a dictionary to look up the word elegence before attempting to use a word to insult someone.

No-one said it was dangerous, but it CAN contravene the Regulations.

The total number of fused spurs is unlimited, but the number of non-fused spurs should not exceed the total number of socket outlets and items of stationary equipment connected durectly to the ring.

A non-fused spur feeds only one single or one twin or one multiple socket outlet or one permenently connected equipment. Such a spur is connected to a circuit at the terminals of a socket outlet or junction box or at the origin of the circuit in the distribution board.

A fused spur is connected to the circuit through a fused connection unit, the rating of the fuse in the unit not exceeding the rating of the cable forming the spur and, in any event, not exceeding 13A

From the above quote, directly from the latest On site Guide, you will see that the last statement effectively prevents you from using more that at MOST two sockets from a fused spur.

The circuit the spur feeds MUST NOT EXCEED 13A, but as one double socket is capable of supplying this load, then you are effectivlet prevented from adding more than one to ensure compliance.

This may be pussy footing around with words to some, but without knowing what will ever be run from those sockets during their lifetime, you must assume each socket outlet will, at some point, be used to supply it's effective maximum load, whether that be via a fan heater, convector heater, kettle or other similar high load domestic appliance.

It is possible to prevaricate all night long on this, but as safety should be thw watchword, I believe it is safest to only run one socket from a spur, UNLESS you install 5A outlets and put 5A plugs on your appliances.

 

[ban-all-sheds]

I have to say that I'm sitting here feeling more than slightly aggrieved. It was never my intention to insult you and I'm utterly amazed that an engineer would regard being categorised as someone who seeks elegant solutions as an insult. Am I mistaken in thinking that some of your design principles are elegant?.

But turning to this:

The total number of fused spurs is unlimited, but the number of non-fused spurs should not exceed the total number of socket outlets and items of stationary equipment connected durectly to the ring.

A non-fused spur feeds only one single or one twin or one multiple socket outlet or one permenently connected equipment. Such a spur is connected to a circuit at the terminals of a socket outlet or junction box or at the origin of the circuit in the distribution board.

A fused spur is connected to the circuit through a fused connection unit, the rating of the fuse in the unit not exceeding the rating of the cable forming the spur and, in any event, not exceeding 13A

From the above quote, directly from the latest On site Guide, you will see that the last statement effectively prevents you from using more that at MOST two sockets from a fused spur.

I find it hard to agree with that deduction. The wording quite distinctly differentiates between non-fused and fused spurs, it explicity states that non-fused ones can only supply one socket and makes no such restriction for fused ones.

The circuit the spur feeds MUST NOT EXCEED 13A, but as one double socket is capable of supplying this load, then you are effectivlet prevented from adding more than one to ensure compliance.

It does not say that and it does not imply that. It says, quite clearly, that the fuse must not exceed the rating of the cable forming the spur and must not exceed 13A. It does not say that the theoretical load of appliances plugged into every socket on the spur may not exceed 13A. And your argument is already starting to look a little self defeating, since one double socket can generate 26A - shouldn't you be claiming that only one single socket should be used?

This may be **** footing around with words to some, but without knowing what will ever be run from those sockets during their lifetime, you must assume each socket outlet will, at some point, be used to supply it's effective maximum load, whether that be via a fan heater, convector heater, kettle or other similar high load domestic appliance.

For heavens sake why? We don't do that with multi-way extension leads. We don't do that with final ring circuits - by your argument those should never have more than 1 double socket on either, since 3 x 13A exceeds the rating of the breaker on it. To argue that no circuit should ever have more outlets on it than could simultaneously be used to their maximum is ludicrous. Of course the circuits must be properly designed so that they are not overloaded, and they can service the loads expected without activating the overload protection, but we would have an awful lot of very thick cables in our houses if the design was based on the premise that Ib = (N1 +2N2) x 13A where N1 and N2 are the numbers of single and double sockets respectively.

It is possible to prevaricate all night long on this, but as safety should be thw watchword, I believe it is safest to only run one socket from a spur, UNLESS you install 5A outlets and put 5A plugs on your appliances.

In which case you'd allow 2, I suppose, since 3 would exceed 13A?

I agree that safety is of paramount importance, but there are enough instances where the regulations already prohibit things which are not unsafe without people adding to that list. The safety aspect of a 2.5mm spur cable fed by an FCU is no different from a 2.5mm radial, and that is allowed to have a 20A protective device and an unlimited number of sockets.

I know that the regulations are a minimum standard, and in many aspects are a guide, and above you have quoted from the On Site Guide, but I don't see anything in the guide which supports your position. I would also point out that Whitfield explicitly states in his guide that "there is no limit to the number of sockets that can be fed from a fused spur to a ring"

You may be able to make a case in particular circumstances that more than one socket on a fused spur is inappropriate, or possibly even non-compliant if it routinely fails to satisfy the design criteria, but there is no way that you can argue that it is either generically unsafe or non-compliant.

 

[BR]

I was grinningly awaiting a reply to breezer’s post To my disappointment it has been removed

 

[Big_Spark]

Your comment about a double socket is actually INCORRECT.


BS1363:1973(1992) is the BS for all standard sockets and plugs in this country. The BS states the MAXIMUM that must be drawn through any such device as being 13A, whether that be single, double or multiple outlet faceplates, multiple plug adaptors or multiple extension leads. (BS1363-4)

This is the very reason why the Regs count doubles as a single outlet.

 

[Big_Spark]

Ban, you do not agree with my interpretation, thats fine as it is open to debate as the regs are once again as clear as mud on this issue.

I will agree that in principle there is merit in assuming that you can put as many sockets on the spur as you want as it is protected by a 13A fuse in the spur, however if you are adding more than two outlets to the ring, then the best course of action would be to incorporate them into the ring.

It never ceases to amaze me why when people have differing opinions on something, some need to resort to cheap insults..and no Ban that comment is not directed at you

 

[ban-all-sheds]

Your comment about a double socket is actually INCORRECT.


BS1363:1973(1992) is the BS for all standard sockets and plugs in this country. The BS states the MAXIMUM that must be drawn through any such device as being 13A, whether that be single, double or multiple outlet faceplates, multiple plug adaptors or multiple extension leads. (BS1363-4)

This is the very reason why the Regs count doubles as a single outlet.

I trust then that for consistency you are campaigning vociferously for the banning of double sockets, and refusing to fit them in customers' properties. You were arguing that a fused spur must not have more than one socket, because if it did then someone could plug in more than 1 fan heater and (attempt to) draw more than 13A.

If that argument is valid then we must not have double sockets because someone could plug in 2 fan heaters and (actually) draw more than 13A. (Despite what the regs say )

But anyway - even though I'm wrong about counting sockets the way I did I still don't agree that Ib = N x 13A is the way to go.....

 

[ban-all-sheds]

I was grinningly awaiting a reply to breezer’s post To my disappointment it has been removed

Aaawwww - I missed it - what (paraphrased) did he say?

 

[ali68]

So you say no more then 13amps, from a double socket, how many households will you go in and see the kettle beside the toaster, quick sum says I'm drawing 17.5 amps at breakfast time.

This is just an observation I am not disagreeing with your quote of the regs.

 

[breezer]

it has been removed because "some one" pressed the "Alert Moderators" link, i basically gave my opinion of FWL_Engineer

or to be more precise my opinion of his comments and more to the point the way he does it.

but it does not take long to figure out who it was.

 

[ban-all-sheds]

Ban, you do not agree with my interpretation, thats fine as it is open to debate as the regs are once again as clear as mud on this issue.

Have you come for the five minute debate, or the full half hour ?

I will agree that in principle there is merit in assuming that you can put as many sockets on the spur as you want as it is protected by a 13A fuse in the spur, however if you are adding more than two outlets to the ring, then the best course of action would be to incorporate them into the ring.

That is a valid position to take as a principle of elegant design, but there are circumstances where I might have to debate that as well. I'm sitting here looking at a wall above a desk which has 4 double sockets on it, fed by a 13A FCU off the ring main. It is a temporary installation, and it is designed to supply mobile phone chargers, laptop chargers, modems, low voltage desk lamps etc. As it is fused, it is perfectly safe. As it is temporary it made more sense to wire it as a spur than to extend the ring to a row of sockets 1.3m above the floor... It is also more elegant (in both senses) than the other alternative of multiple trailing sockets plugged into ring main sockets. But conversely, I've been building some shelving in my son's bedroom, and that also has wall mounted sockets designed to feed low-current devices, like TV, stereo, Playstation, laptop etc. From a loading POV I could have had a spur, but as it is not a temporary installation I have cabled it as an extension to the ring, as in this case it's a better solution.

It never ceases to amaze me why when people have differing opinions on something, some need to resort to cheap insults..and no Ban that comment is not directed at you

I should hope not! I only use the finest, most expensive insults that money can buy