Basic FCU spur query

[Somethingsrotten]

I have noticed that in our kitchen we have a socket on a spur and I can't find an example like it anywhere online, so just wanted to check if it's normal.

To explain, there is an FCU coming off the cables of the circuit, not from a socket or a junction box. Inside the FCU there are 2 cables connected to Supply, which go each direction to the circuit, then another cable going out of Load which goes to one socket.

Does this sound typical?

Just to note I'm not planning to change anything, just want to understand. Thanks for any info.

 

[rsgaz]

Yes, all accessories on a ring circuit, whether they are normal sockets or FCUs, are connected in a loop which starts at the consumer unit(fusebox), goes to each accessory in turn and then goes back to the CU. So there's always two cables feeding them.

 

[Somethingsrotten]

Great, thanks!

 

[rsgaz]

 

[JohnW2]

To explain, there is an FCU coming off the cables of the circuit, not from a socket or a junction box. Inside the FCU there are 2 cables connected to Supply, which go each direction to the circuit, then another cable going out of Load which goes to one socket. Does this sound typical?

It's obviously impossible to be sure from afar, but it sounds as if yopu afre describing an FCU which is part of a ring circuit (hence the two cables on the Supply side), with the (fused) Load side of the FCU supplying just one socket via the 'spur' cable.

If there is just one socket on that spur, then the FCU is actually unnecessary - the socket could be supplied just from a junction box on the ring - or, much more commonly, directly from one of the sockets on the ring. It's possible that the person who installed it didn't realise/understand that. However, should one ever wish to feed more than one socket via that spur, then an FCU would be necessary (a 'fused spur'), so it's also possible that it was done deliberately with possible future additions in mind.

Kind Regards, John

 

[Somethingsrotten]

Thanks, it might be because it's the socket our cooker is plugged into, therefore it has a switch above the counter while the socket is beneath...

 

[JohnW2]

Thanks, it might be because it's the socket our cooker is plugged into, therefore it has a switch above the counter while the socket is beneath...

Is it a single socket? If so, then the absence of need for an FCU is pretty 'obvious', since there will be a fuse in the plug that is plugged into the socket, so nothing really gained by having a second fuse in an FCU.

Kind Regards, John

 

[Somethingsrotten]

It's a double, so I guess that's why they did it?

 

[winston1]

Even a double socket does not need the fcu.

 

[JohnW2]

It's a double, so I guess that's why they did it?

No. The regulations allow either one single or one double socket to be wired via an unfused spur from a ring circuit (i.e. no FCU). I mentioned a single because the reason for not needing an FCU is then totally obvious, but the same remains the case with one double socket.

Kind Regards, John