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.