Is this a spur off of a spur?

[kalibre]

Hi,

Need some advice on the fitting of an FCU and a socket to en existing ring final. Basically I'm aiming to spur an FCU from an existing socket in my lounge. This FCU will be used for a wall mounted fire drawing no more than 6.5 amps.

Whilst I'm at it I thought I may also add a double socket. This is where it gets tricky. Should/Can I spur the new socket from the old one and then spur the FCU from the new socket? I understand that the socket will not be protected by the FCU in this case, but not sure if this constitutes a spur from a spur which I know is a no no.

Alternatively should I spur the FCU from the old socket and then add the new socket AND the fire to the 'load' side of the FCU, thus having the socket and the fire sharing 13 amps?

Any advice would be greatly appreciated.

Many thanks,

Kalibre

 

[sparkytim]

I FCU or 1 Sgle skt or 1 Dble skt max allowed of an UNFUSED spur

See BRB Pg 362

 

[Couleddie]

If you spur the FCU off the ring and then wire another socket on the supply side of the FCU then this is a spur off a spur and is a no no. The best way to do this would be to extend the ring from the socket you were planning to take the spur off. Basically this would just mean running two cables instead of one.

 

[kalibre]

Thanks for the quick replies. I'll think about extended the ring, although this would require a cable join would it not? If so how would this best be done?

So could I still wire in the new socket and the fire on the 'load' side of the FCU? This way the whole spur would be fused at 13amp.

 

[Couleddie]

Crimps are best as they're permanent and take up less room. Not really a fan of connector blocks but as the joint is accessible they can be used, providing they are the correct size.

If you're extending the ring there's no need to wire the new socket off the supply side of the FCU. By doing that you would be restricting the socket outlet to 6.5A when the fire is on. You can always wire the new socket on the ring and THEN spur off to the FCU but if I was going to the effort of extending the ring i'd avoid spurs altogether.

 

[ProDave]

Actually I quite often deliberately spur the feed to FCU's

IMO having three 2.5mm t&E's terminating in a 1G back box can get a little crowded. So I much prefer where convenient to feed an FCU as a spur from an adjacent socket so there are only 2 cables to terminate in the FCU.

 

[Couleddie]

Actually I quite often deliberately spur the feed to FCU'sIMO having three 2.5mm t&E's terminating in a 1G back box can get a little crowded. So I much prefer where convenient to feed an FCU as a spur from an adjacent socket so there are only 2 cables to terminate in the FCU.

Why would the feed from an FCU be in 2.5mm? You can only supply a max of 13A.

 

[ianmacd]

Why would the feed from an FCU be in 2.5mm? You can only supply a max of 13A.

Unless someone puts an 'upgraded' fuse in and it can take more. Besides it also depends on the installation method too do not forget.

 

[Couleddie]

Unless someone puts an 'upgraded' fuse in and it can take more. Besides it also depends on the installation method too do not forget.

Unlikely on an FCU with a BS1361 fuse. A plug, yes!

If we allowed for idiots all the time we'd wire everything in 10mm!

 

[ProDave]

Why would the feed from an FCU be in 2.5mm? You can only supply a max of 13A.

When I wire an FCU to feed a 13A socket, say for a washing machine, I still use 2.5mm to feed from the FCU to the socket because it just "feels" wrong using anything smaller, though I am well aware technically you can. Plus it saves going off to fetch another drum of cable.

 

[ianmacd]

When I wire an FCU to feed a 13A socket, say for a washing machine, I still use 2.5mm to feed from the FCU to the socket because it just "feels" wrong using anything smaller, though I am well aware technically you can. Plus it saves going off to fetch another drum of cable.

Also, what if someone 'upgrades' the fcu to a dsso?

 

[Couleddie]

Also, what if someone 'upgrades' the fcu to a dsso?

If that someone is an electrician then he would of course check and test accordingly. Whatever anybody else does is their responsibility. You can't predict the future! Personally, I would take into account the possibility of future factors whatever the job but you can realistically and reasonably only go so far. Am I not correct in stating that if I install something that is designed for its intended use, adheres to regulations and is tested satisfactorily then I am responsible for THAT install. If someone decides to 'doctor' that installation thereafter then it's really not my problem. We all know that the general population does stupid things and whatever we do to make things safe there will always be someone to render it unsafe.

 

[kalibre]

Crimps are best as they're permanent and take up less room. Not really a fan of connector blocks but as the joint is accessible they can be used, providing they are the correct size. If you're extending the ring there's no need to wire the new socket off the supply side of the FCU. By doing that you would be restricting the socket outlet to 6.5A when the fire is on. You can always wire the new socket on the ring and THEN spur off to the FCU but if I was going to the effort of extending the ring i'd avoid spurs altogether.

Cheers. The problem I have with extending the ring is that the 'parent' socket is only a 1G with a 25mm box, meaning that 3 cables will be tight, whereas 4 cables and joins would be nigh on impossible. I could always channel out a larger space but that is already a finished surface etc etc...

I think I may go for the spur to the FCU then connect both the socket and the fire to the load side. I am happy to accept a 6 amp limit on the socket when the fire is on as it's not going to have much plugged into it.

The question is, is this all ok from a regs point of view? Is it a concern that the fire will only draw 6.5 max but the FCU is rated for 13?

(You said 'supply side' above but I'm pretty much sure you meant 'load side')

 

[ProDave]

Also, what if someone 'upgrades' the fcu to a dsso?

If someone does that (already said not my responsibilty if someone modifies it so it doesn't comply with regs) then it will be better off because I used 2.5. If I had used smaller cable, (as I could from an FCU) the situation would be even worse wouldn't it.

So using 2.5 on the output side of an FCU makes it LESS dangerous if someone changes the FCU for a socket.

 

[ianmacd]

If someone does that (already said not my responsibilty if someone modifies it so it doesn't comply with regs) then it will be better off because I used 2.5. If I had used smaller cable, (as I could from an FCU) the situation would be even worse wouldn't it.So using 2.5 on the output side of an FCU makes it LESS dangerous if someone changes the FCU for a socket.

That was my point. Use the 2.5 not the 1.5.

 

[Couleddie]

I'm not disagreeing with any of that but it really does raise the question of how far you go in trying to provide for every eventuality, most of which, in reality, are not going to arise.

It's up to the individual amending the installation at any given time to take responsibility for the changes and ensure all factors are acceptable. NOT the person who originally installed it.