Spuring off a Switched Spur

[claret73]

This may be quite hypothetical for now, but can I take a feed out of the incoming side of an FCU (If it was either a radial or Ring Final) to feed a 2nd FCU which would provide a load out to a boiler?

Spoke to the plumber asking if he has power next to the boiler and mentioned the spur. If it's off the Ring originally then I assume no difference to spurring off a Socket outlet?...Good or Bad Practice? Not looked at it yet, just trying to pre-empt anything.
Thanks!

 

[Octopus]

You can spur off a FCU as long as its on the ring, or radial circuit.

You can't spur off a spur (even if its 2 FCU's protecting 2 cicuits of, say 3A each) - which IMHO is silly as you can spur off a socket to a double socket and plug in 2 3KW heaters!

 

[Adam W]

Technically OK because they're fused, but if it were a ring I'd want the FCUs off that rather than spurred off.

 

[Geoffsd]

You can only have one spur from a point on a Ring or Radial (socket, JB or FCU) - If fused you can have as many outlets as you want - so only 13A.no matter how many you fit on it.

So two FCUs from the same point would not comply.

If on a Radial and same csa it wouldn't be a spur.

 

[topquark]

Off the incoming side, no. Only one spur allowed. From the outbound side (protected by the fuse) then fine.

 

[JUD]

Off the incoming side, no. Only one spur allowed. From the outbound side (protected by the fuse) then fine.

I disagree. The load side of an FCU is fused so spurring off the supply side is no different to spurring off a socket as long as the FCU is connected directly to the ring.

 

[Geoffsd]

I disagree. The load side of an FCU is fused so spurring off the supply side is no different to spurring off a socket as long as the FCU is connected directly to the ring.

But that would be two spurs and 26A from the same point - not allowed.

 

[JUD]

But that would be two spurs and 26A from the same point - not allowed.

So when you spur from a socket with a 13A plug in it to a 13A fused spur, that's also 26A. What's the difference???

 

[Geoffsd]

Maybe, but if there were two spurs that would be 39A.

I'm afraid there's no argument on this one.

 

[topquark]

I disagree. The load side of an FCU is fused so spurring off the supply side is no different to spurring off a socket as long as the FCU is connected directly to the ring.

Just re-read the OP and you're right to disagree assuming that the FCU itself is part of the ring (and not spured from another accessory).

 

[JUD]

Maybe, but if there were two spurs that would be 39A.<br>
<br>
I'm afraid there's no argument on this one.

Where did you get 39A from???

You have one FCU connected directly to the ring like a socket-outlet would be. This is not the spur, the cable running off the fused LOAD side of it (which is no different to the flex of something plugged into a socket-outlet) is the spur.

Then, just like you would spur off a socket-outlet you run a spur off the SUPPLY side of the FCU.

 

[pinkonthebrain]

if you use 4mm you can have radial of a ring ,

 

[flukey]

if you use 4mm you can have radial of a ring ,

that sounds like fun, connecting 2 2.5s and a 4mm into a socket :whatchutalkingabout

 

[grimysparks80]

Depending on what the first FCU is doing, id use it to supply 2 new ones. One for the original equipment and one for the boiler. That way everything is protected by the 13a fuse in the main FCU and youre not doing anything wrong.

 

[Geoffsd]

Apologies - I didn't realise the first FCU was actually on the Ring.

 

[claret73]

Didn't mean to start a war Lads! I haven't looked at it yet, but Jud that's what I was thinking initially. If the spur is connected to a ring, then taking off the load is only a spur off that like a socket. I guess I'd need to test to see that there aren't already Spurs in existence (which might be highly unlikely...)

GrimySparks, that sounds a useful option. Hopefully I've got this right & maybe is unnecessary?? I could put a new FCU next to the original, Split the legs and bridge between. Both now wired into the ring. Keep the new at 13A & take the load 1x 2.5mm to the 2nd FCU. Then Load out of that to the Boiler. If the original is next to the Boiler in proximity then could just take my flex out of the first FCU & fuse down, marking the FCU as the Boiler.

 

[DarrenA]

You can spur off a FCU as long as its on the ring, or radial circuit.

You can't spur off a spur (even if its 2 FCU's protecting 2 cicuits of, say 3A each) - which IMHO is silly as you can spur off a socket to a double socket and plug in 2 3KW heaters!

And even worse, the regs allow you to use unfused socket doublers (the small cube things) and essentially double the draw! So this could potentially be 52A/12KW (in practice < 32A or the ring MCB would trip but still more than 2.5mm is allowed) from a double socket off a spur and be compliant but 2 FCUs carrying 26A max is for some reason not ok?

 

[DarrenA]

Oops newb here! Hadn't realised I was replying to a 12+ year old thread.

Are threads normally locked after a while so this can't happen?

 

[littlespark]

Oops newb here! Hadn't realised I was replying to a 12+ year old thread.

Are threads normally locked after a while so this can't happen?

Obviously not. Lol


Those cube adapters are always fused… they have to be. If not, then you’re buying unsafe non compliant products.

 

[DarrenA]

Obviously not. Lol


Those cube adapters are always fused… they have to be. If not, then you’re buying unsafe non compliant products.

That's not the case, some are unfused and the regs say only ones with 3 or more sockets need to be fused (unless the regs have changed?)

Here just a couple of examples:

Adaptor

BS1363Multiple adaptor for plug socketsTurn a single socket into twoCompact cube shapeEasy grip design

www.toolstation.com

Masterplug 13A 2 Way Unfused Socket Adaptor - White | Wickes.co.uk

Masterplug 13A 2 Way Unfused Socket Adaptor - White

www.wickes.co.uk