I want to install a light in a cupboard I'm building. My plan was to spur off the existing socket to a 13A fused light switch. I say was, because I've just discovered that the socket is itself a spur. I've always thought that you can't spur off a spur, however I have read online that it's ok for a light switch providing the socket is fused. So is it still possible to do what I want with some further modifications, or am I screwed? If it's possible then I'd appreciate full instructions on what I need to do. Specifically with the socket and any fuse changes. Also, can I use 2.5mm T&E from the switch to the light fitting, or do I have to drop to 1.5mm or 1mm?
Light switch spur
- Thread starter markjg123
- Start date
Is the socket spurred directly from the ring unfused or is there a fused connection unit (spur) before the socket
In that case you'd need an fcu before the socket then you can feed your light from the socket via a switched fcu.
Yes, but there is no need. Fit a 13amp fuse in the FCU switch, and you can use 1.5mm, but 3amp means you could use 1.0mm.
You can do if it will fit in the light fittings terminals, 1mm might be easier.
No, swap the 13amp fuse for a 5amp. 13amp in the FCU, which feeds your socket+ light, then a 5amp in the FCU to protect the light part of your circuit.
If you put an fcu before the socket you dont really need a second fcu just a light switch as the original 13 amp fuse will protect the lighting cable aswell. (By a long way as you plan to use 2.5mm)
Basically, with a Ring Final Circuit you can run a Radial Leg (Called a Spur) from it either fused down or not - the max load on that spur can be one twin or one single socket (or one Fused Connection Unit - switched or not switched as required) .
You can actually do the same with a correctly sized Radial Circuit too (say 4.0 or 6.0 perhaps),
A Ring Final Circuit is usually 2.5 T & E and a spur from the ring is usually 2.5 to run one twin or one single socket or one Fused Connection Unit (switched or unswitched) , that can take a 13A max fuse. On that fused side of that 13A fuse you can run as many items as you want and you might decide to use another FCU to run a lighting circuit on say a 3 or 5 amp fuse for instance , any spur from the ring can do the same, you can atually spur from a radial final circuit but that`s a different topic.
Think of Spurs in Electrics as you might do to think of Spurs on train lines - a branch off the main line.
Some people wrongly call an FCU (switched or unswitched) a "Spur" it is not a spur, in essence the cable itself is the spur whether from a ring or a radial final circuit.
You can actually do the same with a correctly sized Radial Circuit too (say 4.0 or 6.0 perhaps),
A Ring Final Circuit is usually 2.5 T & E and a spur from the ring is usually 2.5 to run one twin or one single socket or one Fused Connection Unit (switched or unswitched) , that can take a 13A max fuse. On that fused side of that 13A fuse you can run as many items as you want and you might decide to use another FCU to run a lighting circuit on say a 3 or 5 amp fuse for instance , any spur from the ring can do the same, you can atually spur from a radial final circuit but that`s a different topic.
Think of Spurs in Electrics as you might do to think of Spurs on train lines - a branch off the main line.
Some people wrongly call an FCU (switched or unswitched) a "Spur" it is not a spur, in essence the cable itself is the spur whether from a ring or a radial final circuit.
The ceiling rose, lamp holder, and flex, will likely only be rated for 6amps, so I would suggest a 5amp fuse to protect those.
Thanks. This is a really clear and helpful description.
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