Lighting on ring main...

[Newbie90]

Hi all,

I changed a light pendant at a friends house and found his lighting circuit in the extension (2 lights) is wired off the ring main!!

I have looked everywhere and cannot find a FCU, so can only assume it is in a junction box under the floor!

Carpets have recently been fitted so bit of a nightmare lighting floorboards and tracing. The cable to the light switch is in 1.5mm t&e.

I can replace the light switch with a FCU and put the light switch beside it, so it is fused down. Just wanted to know if this is ok as the cable supplying the FCU would only be 1.5mm.

Is there a risk of that cable overloading as it would be connected to the ring by a junction box (I assume)?

Thanks

 

[davethsparky]

Is this a serious question?

Its a times like this I wish someone had written some kind of book with details of standard circuits and minimum cable sizes for those circuits. Maybe they could call it something like an 'on site guide' !

 

[staggie65]

No, ring on 2.5TE off 32A mcb. 2.5mmTE to FCU, 3A should suffice, then 1.5 to fitting

 

[micknew]

Hi all,

I changed a light pendant at a friends house and found his lighting circuit in the extension (2 lights) is wired off the ring main!!

I have looked everywhere and cannot find a FCU, so can only assume it is in a junction box under the floor!

Carpets have recently been fitted so bit of a nightmare lighting floorboards and tracing. The cable to the light switch is in 1.5mm t&e.

I can replace the light switch with a FCU and put the light switch beside it, so it is fused down. Just wanted to know if this is ok as the cable supplying the FCU would only be 1.5mm.

Is there a risk of that cable overloading as it would be connected to the ring by a junction box (I assume)?

Thanks

Best advice would be to get a sparks in to sort it or ask in your local B&Q.

 

[kingeri]

If there is only one light switch, why use an FCU and a light switch? Why not just use one switched FCU with a 3A fuse?

 

[Dave 85]

Putting an FCU instead of the switch (why you would then put a light switch next to it is beyond me) would reduce the risk of over-current but its still not a proper job because you've still got a bit of 1.5 feeding it that has the wrong device. Personally I'd probably inform your friend that his extension has been wired by cowboys and leave it at that.

 

[kingeri]

It could be argued that the light is a fixed load...........but that's opening up another can of worms. Lol. Sigh.

 

[wersolaruk]

Take the carpet up like a proper spark ha

 

[telectrix]

change the light switch for a 3A FCU. advise that the 1.5mm from RFC is protected downstream and could do with improvement. next job.

 

[Octopus]

Yeh, but under the carpet, under the floorboards is accessible ain't it.

 

[telectrix]

Yeh, but under the carpet, under the floorboards is accessible ain't it.

it's only accessible if you want to put forward the argument for not using MF connections. cut a trap in the floor, carve a flap our of the shagpile, then, using a broad felt tip marker, write on the wallpaper " cable joint here" with a down pointing arrow. :stupid::13:

 

[Octopus]

it's only accessible if you want to put forward the argument for not using MF connections. cut a trap in the floor, carve a flap our of the shagpile, then, using a broad felt tip marker, write on the wallpaper " cable joint here" with a down pointing arrow. :stupid::13:

Got my stetson on tonight!!

 

[Guitarist]

It could be argued that the cable will only carry 3 amps, and therefore be safe, once you fit an SFCU in place of the light switch, but that's always assuming that the 1.5mm doesn't go somewhere else besides this one lighting circuit.
It's been installed by a cowboy and needs sorting out properly.

 

[guest119]

Needs a rewire from db to switch, or pendant.

Is there not some bs or manufacturers literature that goes against using the likes of an fcu for a light switch?
Regarding the number of switch activations, in the lifetime of the accessory. IE, a light switch is intended to be switched on and off often but an fcu is not?????

Boydy

 

[Guitarist]

Needs a rewire from db to switch, or pendant.

Is there not some bs or manufacturers literature that goes against using the likes of an fcu for a light switch?
Regarding the number of switch activations, in the lifetime of the accessory. IE, a light switch is intended to be switched on and off often but an fcu is not?????


Boydy

No.
Common practice for conservatories, and not dangerous if done correctly.