What can i do with an FCU

[focusblue]

Hi everyone,

I am a longtime lurker first time poster, Heres my question.
I'm building a partition wall and need to run some electrics into it.
What i am planning to do is to take a spur from a nearby socket, (on the downstairs ring), into a 13A FCU.
From the FCU i am hoping to run a 1.5mm cable to supply LED lights and a 2.5mm cable to supply another double socket.
Both cables will come from the same FCU.
Will this work? Is this safe?
Many thanks for your replies and apologies if this has been covered elsewhere.

 

[Spark123]

Not really as your lights will be fused at 13A.
If you have an FCU fused at 13A fed from the Ring Final circuit (you can only spur if the socket is on the ring and not already a spur), then you can use this to feed a 13A socket and a 3A FCU to supply the lights.
Also note that if you are concealing T&E cable it should be on an RCD which is fine if your Ring final circuit already is.

 

[ban-all-sheds]

And there's no point using 2.5mm² for the cable to the socket...

 

[focusblue]

Not really as your lights will be fused at 13A.
If you have an FCU fused at 13A fed from the Ring Final circuit (you can only spur if the socket is on the ring and not already a spur), then you can use this to feed a 13A socket and a 3A FCU to supply the lights.
Also note that if you are concealing T&E cable it should be on an RCD which is fine if your Ring final circuit already is.

Thanks for the prompt reply.
Yes its an existing ring circuit protected by an rcd.
So if i understand correctly i could run a spur cable into a double socket and then take a cable from new double socket into a 3A FCU to supply the lights.

 

[focusblue]

And there's no point using 2.5mm² for the cable to the socket...

Cool. I'll bear that in mind.
I had just assumed that the existing wiring would be 2.5mm.

 

[Spark123]

You can get away with smaller cable after the FCU but there is nothing wrong with using 2.5mm.
The cable from the ring to the 13A FCU must be 2.5mm or larger.
Using 2.5mm to supply lights could be a pain in the backside tho.

 

[focusblue]

You can get away with smaller cable after the FCU but there is nothing wrong with using 2.5mm.
The cable from the ring to the 13A FCU must be 2.5mm or larger.
Using 2.5mm to supply lights could be a pain in the backside tho.

What i'm thinking is: 2.5mm from the ring to the new double socket-2.5mm from the new double socket to a 3A FCU-1.5mm from the 3A FCU to the lights.
I was planning to drop the 13A FCU between the ring and the new double socket. Unless you think it necessary??

 

[Spark123]

Yes, you need to have the 13A FCU before the first socket.
Use the 13A FCU to feed both a 3A FCU and the double socket so they are both protected by the 13A fuse.
You must use 2.5mm or larger on the ring circuit side to feed the 13A FCU.
After the 13A FCU you may get away with smaller as the cable is now protected by a 13A fuse.

 

[focusblue]

Yes, you need to have the 13A FCU before the first socket.
Use the 13A FCU to feed both a 3A FCU and the double socket so they are both protected by the 13A fuse.
You must use 2.5mm or larger on the ring circuit side to feed the 13A FCU.
After the 13A FCU you may get away with smaller as the cable is now protected by a 13A fuse.

Understood.
Thanks for your help its been invaluable.
I had a little knowledge before and as we all know a little knowledge is dangerous.
If you ever decide to install a mobile phone mast in your house give me a shout and send you some pointers.....Lol

 

[333rocky333]

If you ever decide to install a mobile phone mast in your house give me a shout and send you some pointers.....Lol

I do a lot of pub work and they have them.
I heard that you get paid if you stick one on your property, is that true.

 

[ban-all-sheds]

Enough to cover the cost of all the Bacofoil hats?

 

[focusblue]

If you ever decide to install a mobile phone mast in your house give me a shout and send you some pointers.....Lol

I do a lot of pub work and they have them.
I heard that you get paid if you stick one on your property, is that true.

You heard correctly, the operators do pay rent to the property owner for use of the space. However there is absolutely zero likelihood that any of the mainstream operators would install on a domestic house. The only reason they use blocks of flats is because they can't get the height they need otherwise.
They tend to prefer commercial property or farms for major sites and minor sites would be installed on pubs, shops and beside the road.

As for tin hats..... i couldn't comment. I was going bald before i started working around them and i'm a jaffa by choice so unless i grow an extra limb i'll never know.

 

[Steve]

You heard correctly, the operators do pay rent to the property owner for use of the space. However there is absolutely zero likelihood that any of the mainstream operators would install on a domestic house. The only reason they use blocks of flats is because they can't get the height they need otherwise.

I seen one on a 2 storey building once, it was a Co-operative store. Hutchinson antenna. Theres not just the antenna, though, theres all the grey boxes they have to install too. In this case, the antenna was mounted to the brickwork, on standoff brackets, and stood with its top just below the apex of the roof. This was the back of the store, so it wasnt visible from the front. Nobody knows it is there At first floor level is a flat roof, and all the equipment is mounted there. Only an SWA cable goes down to the ground, with a box (presumably electric meter) near ground level.

 

[plugwash]

And there's no point using 2.5mm² for the cable to the socket...

While it's not strictly necessary I would always use at least 2.5mm for wiring up sockets, that way if I decide to rearrange things in a way that eliminates the FCU I don't have to worry about the cable being inadequate.

 

[333rocky333]

Although not in the regs, I am pretty sure it was always 2.5 minimum for a 13a socket.
Good practice and all that, may have been Niceic as well.
Exeption being 1.5 pyro.