Spur with two sfcu on it

[Lighting]

Hi all is this ok to run two sfcu like this ?


Or should i run it like this

 

[Lighting]

Thanks for all the reply's i think i best put the 13a sfcu in as it will only take 5 mins

 

[mickys86]

Ok, the part of the diagram on page 425 shows a spur off the ring main at 9 oclock. The 13A FCU is limiting the current that can flow through to 13A therefore protecting the cable. The OP diagram 1 shows a spur going straight to the first FCU and then on to another FCU. Therefore with 13A fuses put in each it is possible that the total draw could be 26 Amps thus overloading the cable. The 3 amp fuses fitted to the FCU`s are irrelevant as they are protecting the cable going out from the FCU to the appliance.

Now I appreciate that 6 amps, or the load from a boiler and a light (which is going to be less in all likleyhood) is not going to damage the supply cable however the light and the boiler are " fixed equipment" therefore the relevant part of the diagram is at 6 oclock where only 1 fixed item is allowed.

The reasoning for this reg IMHO is that should the fixed equipment be changed in the future, say an immersion for a boiler and a socket for the FCU running the light then you have an overloaded cable.

I refer to my previous post regarding fixed equipment on spurs.

I get it now. That and what ipf explained. It'd be best to incorporate the spur as part of the ring or put the 13a spur in.


We only do new builds or complete refurbs when we do domestic, the rest is commercial work and in both circumstances I'm supervised. Always learning and even thou this wasn't my post I learned something today.

Sorry to bore you ez and biff. Was there nothing else on the forum you could've read??

 

[ezzzekiel]

 

[Simlec]

First pic a no go, second pic correct.
not sure why this has got to fourth page.

 

[TaffyDuck]

ezzzekiel, yes as I said.

 

[TaffyDuck]

First pic a no go, second pic correct.
not sure why this has got to fourth page.

Well its sorted now

 

[ezzzekiel]

Either option would be ok unlimited outlets allowed as the first fcu limits the total draw to 13a from that leg of the ring

 

[pencilpusher]

Either option would be ok unlimited outlets allowed as the first fcu limits the total draw to 13a from that leg of the ring

Sorry but there is no 13 amp FCU on the first drawing???

 

[TaffyDuck]

Said my piece Pic 1 is wrong, bored now.

 

[pencilpusher]

Said my piece Pic 1 is wrong, bored now.

Chill Taffy, I am not arguing with you, I am agreeing!

 

[ezzzekiel]

No it's not your right it's fused at 3a which still makes the circuit correct
everything from the fcu in picture one is limiting the draw to 3a

 

[mickys86]

Either option would be ok unlimited outlets allowed as the first fcu limits the total draw to 13a from that leg of the ring

That's what I was thinking at first but if second spur was connected to supply side of first spur then it would be wrong.

Why is everyone getting uptight about this?? It's Sunday..... Chill day

 

[pencilpusher]

No it's not your right it's fused at 3a which still makes the circuit correct
everything from the fcu in picture one is limiting the draw to 3a

OK but he stated it would be "looped". I take it that means the second FCU is fed from the supply of the first FCU and not the load side. That would mean the 3 amp fuse would protect the light and not the spur cable and that the second FCU could draw up to 13 amps?? That's my take on it but I may have read it wrong.

 

[ezzzekiel]

Yes but then the circuit wouldn't be wired correctly so not a design fault, not uptight about it but to say the circuit is wrong is not true, it may not be ideal or suitable for the use intended but it is correct as far as design goes, outlets are unlimited from fcu taken from the ring as the fcu be it 3,5,13a will limit the loading from the leg to the rating of the fuse.

As PP says above looping would be incorrect but ops original post was just a block diagram

 

[pencilpusher]

Guys, I think this is interesting even if some do not! I am certainly not uptight about any of it.