wiring an outside light up to an inside light switch

[lhkr]

Hi,

I have just run a new 2 core and earth cable from a victorian street lamp in my garden. The cable is currently under the floor boards waiting to be wired in. I want to connect it to an existing switch point which currently has a one way/one switch switch on the wall. I have bought a double switch (not sure if its 2 gang/2 way but it does have 2 sets of com + L1 +L2) and tried many combinations but cannot get the two lights 2 work independently. The power for the existing switch comes from the overhead light and I'd like to use that if I can. I can easily crawl under my floorboards but cutting holes in victorian plaster can be hazardous and messy so would like to avoid as little damage as possible and therefore want to use the existing single power supply if possible.

Can you suggest the best way forward?

Thanks

Keith

 

[Spark123]

Normally there is not a neutral in the back of the light switch. To overcome this you may run a neutral in from the overhead light, use a piece of 3c+earth to replace the existing cable. If the cable is Red/Yellow/Blue, sleeve the yellow conductor red and blue conductor black at both ends. If it is harmonized, use brown sleeve on black (live) and blue sleeve on grey (neutral). Connect the cable in the overhead light to permanently live, switch live for the overhead light, neutral and earth. At the light switch end connect the permanently to C and loop to the other C with a short piece of wire. Connect the switch live for the overhead light to L1 gang 1. Earth to the back box. Connect the live from the lamppost to L1 gang 2. Connect the neutral wires together either with 5A terminal block or through crimp. Connect the earths together preferably in terminal block and T to the back box.

 

[Lectrician]

Umm - T+E out across the garden?? No conduit or armoured cable??

Your switch, does it have only 2 cores from the 'overhead' light?? I expect so, a live and a swithed live return. NO NEUTRAL - thats the key!

If running a 3 core from switch to 'overhead' is difficult, then maybe you can you pick up from a low-level socket, and connected via a switched fused connection unit??

With access below, how about the Consumer unit etc??

Before connecting, let us know how you have wired the outside kit - sounds a little less then ideal??

We wont mention part-p.

 

[Spark123]

We wont mention part-p.

Thankfully Fife is in Scotland

 

[Lectrician]

We wont mention part-p.

Thankfully Fife is in Scotland

Did they have a victorian era

 

[Spark123]

------------------

IIRC, the cable should be burried in a conduit or earthed sheath SWA at a depth which can't be unintentionaly disturbed. They should also be tiled / warning taped over at a depth before the cable can be disturbed.

 

[lhkr]

Thanks for the info, its much appreciated. I'll digest your comments and then attempt something at the weekend. If you see any bright flashes in the sky north of the watford gap then you'll know that I tried......

re the cable in the garden, I've buried it in conduit 2 feet down (just to make sure I don't spear it with a fork). The cable that was there before was simply buried 2 inches from the surface with no protection. Also, the cable coming from the supply in the overhead light is also 2 core and earth (ie 1 red, 1 black, 1 earth)

Thanks again

 

[lhkr]

Hello again!

Tried a few of your suggestions but didn't get very far. Have now decided to go with option (b) which was to "pick up from a low-level socket, and connect via a switched fused connection unit"

What I intend to do is to locate one of the cables leading to a low level socket and put in a junction box. I'll have a spur coming out of that which will lead to a second junction box. Also leading into that will be the cable from the victorian lamp, and another leading out which will be the cable to the fused switched.

What I'd like to know is which type of junction boxes should I use. I think that I need a 30AMP one for the first box but am unsure what type I need for the box which has the light/switch cables running through it.

Thanks

ps FYI: I have now laid another cable to the light so I have 1.5mm armoured cable inside a conduit.

 

[Adam_151]

You should put a 30AMP JB in the ring, come off that with 2.5mm², bring that straight into the FCU (supply terminals), then take the feed for the light straight from that (load terminals)

(you could also take it JB - > FCU -> Switch -> light, if you use an US-FCU)