Looping in at a Light Switch ?

[BotchItYourself]

I want to connect an outside light for my patio. I have a nearby interior light from which I can take the power. Obviously, one solution would be to take the power from the interior light to a junction box and from there have two cables running to the exterior light and light switch respectively. However, this would mean hiding the junction box in an area that will become inaccessible following plasterboarding & skimming and I feel uncomfortable doing this.

I seem to remember from reading previous posts - I can't find them now - that all the necessary connections could be made at the light switch rather than at a junction box i.e. two cables going to the switch one from the power source and one from the outside light. Is this true ? Is it legal ? If so, could someone tell me which wire goes where at the switch.

 

[ban-all-sheds]

Perfectly legal - take a T/E cable from the permanent live lighting circuit to the switch - neutral goes straight through to the light, live goes into COM and comes out of L1 and goes to the light.

If you're dextrous you can remove a section of the sheath, cut the L & E cores to connect them to the switch, and leave the N intact, or you can just chop the cable and join the N in a piece of choc-block.

 

[BotchItYourself]

Thanks BAS. I prefer the choc-block solution.

As a supplementary question, is it acceptable to use 3C+E cable as a substitute for T+E by just ignoring one of the wires or is it frowned upon ? I'm using old colours and may not have enough T+E to go the distance.

 

[ban-all-sheds]

You can still buy old cable - lots on eBay, but prices are rising.

Yes you can use 3C+E - don't forget to sleeve the live core with red, and good practice is to connect the unused core to earth at each end and sleeve it G/Y.

 

[BotchItYourself]

Excellent. Thanks again. Just out of interest, when used in this way, is 3C+E comparable to 1mm T+E or to 1.5mm T+E in terms of its rating ?

 

[plugwash]

you can buy it in both 1.0mm and 1.5mm

 

[Steve]

If you're dextrous you can remove a section of the sheath, cut the L & E cores to connect them to the switch, and leave the N intact, or you can just chop the cable and join the N in a piece of choc-block.

in couple of junction boxes at our house, where someone had a decent spark in to install spurs, the ring cable is continuous - somehow he managed to not interrupt the conductors - just remove the insulation and slot it into the terminals with the grub screws out. And they have been done very neatly too - no scrag-ends of pvc hanging off

 

[crystal ball]

If you're dextrous you can remove a section of the sheath, cut the L & E cores to connect them to the switch, and leave the N intact, or you can just chop the cable and join the N in a piece of choc-block.

in couple of junction boxes at our house, where someone had a decent spark in to install spurs, the ring cable is continuous - somehow he managed to not interrupt the conductors - just remove the insulation and slot it into the terminals with the grub screws out. And they have been done very neatly too - no scrag-ends of pvc hanging off

How did he sleeve the cpc

 

[plugwash]

personally i found that cutting the earth but not cutting the live and neutral makes it fit really nicely, that centimeter shorter you get from cutting it is just right to make up for the fact the earth is straight and the other cores aren't.

 

[1974stephen]

where possible I always try and keep the cpc longest so that if it's going to be pulled apart (yeah I know it should have mechanical protection) the cpc will be last to break contact, therefore providing greater safety.

 

[Steve]

crystal ball, iirc, he didn't sleeve the earth. They were the old T+E, with silvery-coloured stranded conductors. And the wiring was very neat, nothing near the bare earth. iirc, i did cut the earth and slip some sleeve over it i think.