Single light switch to double.

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Hi,

I have a single light switch with 1/2 inch capping going to the ceiling light (1.5mm T&E cable). I'd like to add another light in the room, independently switched from the same point and I'm just wondering the best way to approach this.

Should I just be adding an extra 1.5mm T&E or should I switch the cable out for 3-core &E with a Wago box in the floor void? How is this normally done?

Also wanted to ask, has anyone actually pulled this off without pulling the capping off the wall and replastering? In theory a 3-core cable will go into one of the 1/2 inch cappings.

thanks,
S.
 
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Yes, it can be done, but often you find the cable is trapped where the capping falls short of the box or ceiling and the cable is plastered over.
Replacing with a 3 core will give you the required line + 2 x switch wires.

Feed the three core back to the same place the existing cable comes from, then you take a twin and earth to your new light fitting connected to neutral, earth and the second switchwire.
 
You'd have more chance of success if you used 1.0 mm cable instead of oversized 1.5mm.

A look at the CU says this is on a Crabtree B6 61/B06, which according to google is a 6amp breaker. So as far as I can see the guy who fitted the CU was allowing for 1mm, even though it's not actually used. I just added up all the lights downstairs and it comes to 350W. Don't know about the smoke alarms but they can't be much.

I'm just curious, are the switch drops 'allowed' to carry less max current than the main supply path, in the same way that pendants usually have smaller wires than the main lighting circuit? And what does all that imply for the breaker specification?
 
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I'm just curious, are the switch drops 'allowed' to carry less max current than the main supply path, in the same way that pendants usually have smaller wires than the main lighting circuit? And what does all that imply for the breaker specification?
1mm² cable is more than adequately protected by a B6 breaker, and it's also the smallest T+E cable that is allowed for fixed wiring (for everything other than 'lighting circuits' the smallest permitted is 1.5mm²).

Kind Regards, John
 
... it's also the smallest T+E cable that is allowed for fixed wiring

Makes perfect sense now I think about it as any smaller would probably mean people damaging cables when handling them.
 
You may of course use smaller flexible cable - as with the pendant drops.

It's not supposed to, and indeed doesn't, make sense.

1mm² cable is more than adequately protected by a B6 breaker, and it's also the smallest T+E cable that is allowed for fixed wiring .
It is, of course, the smallest made.
Perhaps that's the reason it was thought necessary to prohibit smaller.
 
That's not how evolution works.

Every single mutation which turned the {whatever it was} into a chicken took place in the development of the embryos - an already living {whatever it is} does not mutate into something different.
 
That's not how evolution works. Every single mutation which turned the {whatever it was} into a chicken took place in the development of the embryos - an already living {whatever it is} does not mutate into something different.
I can't really disagree with any of that, but you are rather spoiling a centuries-old 'philosophical' debate (as practised in many a pub!) by bringing the science into it :)

Kind Regards, John
 
That's the second time in recent weeks that you have attempted to conflate philosophy and non-evidential, unscientific practices.
 
That's the second time in recent weeks that you have attempted to conflate philosophy and non-evidential, unscientific practices.
'Philosophical' was in quotes this time and, just in case you didn't get the light-hearted message (a failing you seem to suffer from at times), I did add "as practised in pubs"!

Kind Regards, John
 
Just in case you don't get this light hearted message:

Ignoring evidence and science is destroying the world, and is no more a suitable topic for joking than genocide, child sex abuse, torture, institutional misogyny, racism etc.

The fact that I do not regard the first as funnier than the last five does not mean that I have a sense of humour failure. Some humour is, and should be, edgy and boundary pushing, but I look forward to the day when irrationality and the blatant disregard for science are as unacceptable as the jokes that Bernard Manning used to tell.
 

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