Changing switch plates, loose live found!

I was changing the light switch plates in the kitchen and was a little surprised to see a cable entering one switch that had it's red wire cut flush with the cable and bare. Being a little less trusting than I used to be, on went the power and out came the tester screwdriver. Of course, it's live.

So I've spent a while trying to figure out what's going on. We have:

  1. A 1 gang 2 way switch. This is for the kitchen lights. No problems here - seems to have a normal switch cable and the 3 core 2 way, all wired up correctly.

  1. A 2 gang 2 way. The kitchen light switch is wired up properly (just the 3 core 2 way cable here). The second switch is for an outside light by the kitchen door and is very wrong.

It all works, but the way they've done it seems insane. There are 3 cables entering the switch, one of which is the 3 core kitchen light one which (I believe) we can ignore.

That leaves two cables. One cable is the one with it's red sniped flush with the cable and left exposed. This red is live when the kitchen lights are on, but not when they're not, so my guess is that it's taken off a junction box that feeds the lights. Incidentally it's very close to the metal lug, so a real safety issue.

What about the black? I've not been quite honest, because I've said there are two cables. Actually, it's just one that's been cut open in the switch box! I know this because I can see the unbroken black go from one cable to the other :) . This is presumably the return From the outside light to the neutral section of the junction box.

Anyway, that "second" cable has its red wire connected to the common of the second "gang" of the switch (its black is continuous with the black in the other cable). To overcome the lack of a live input, a small wire connects the L2 (permanent live) of the first gang to the L2 of the second. I'm guessing that someone cut the red wire too short, didn't have enough spare cable and so did this as a working fudge.

Assuming you're still here, any ideas what to do? There's not enough slack cable to pull through to expose any of that red wire, so I can't do what I believe is the right thing and connect that exposed red to the 2nd gand L2 in place of the dodgy crossover.

Reply to
Bromley86
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Just realised that I wouldn't want to use the exposed red in place of the crossover even if I could as it's not a permanent live (i.e. I may want the outside light on when the kitchen lights are off). Still need to figure out what's safe and/or the correct thing to do with it though.

Reply to
Bromley86

The obvious things to do are either find the junction box and disconnect the other end of the offending live or put a connecter on the end of the wire to insulate it in the switch box

Tony

Reply to
TMC

Thanks. The wall box is very shallow and there's no spare cable, so it looks like I'll have to get up into the small roof to get to the junction.

Reply to
Bromley86

[snip] Are you sure? Those tester screwdrivers are notorious for picking up induced voltages from nearby cables.

I /believe/ that given a conductor which a screwdriver shows as live when the switch is on but not-live when the switch is off, it is reasonably safe to assume that one won't get a shock as long as the switch is off.

In any other situation, the obvious conclusion from those screwdrivers needs to be taken with a large pinch of salt (and the conductor assumed to be live).

[BIG snip]

Are you sure that the snipped live isn't coming from the kitchen light (the actual light fitting). Alternatively, it may as you suggest be coming from a junction box.

Either way, the correct solution is to find the other end, and make sure it is disconnected it (if it /is/ already connected).

Reply to
Martin Bonner

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