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on a lighting circuit. Â I have junction box wiring. Â I want to add another socket on it' own switch.
I have found a close by junction on the right circuit but I'm not sure how to identify which of the three wires is the perm live (and therefore one I would spur from)
I haven't opened the box yet doing my research first. Â can't easily trace the wires without disrupting other rooms
tips? Â other than get a sparky in as I want to learn.....
Lick each one in turn. When you find yourself sitting in the opposite corner of the room, you've found the correct wire.
Alternatively, mains tester screwdriver?
You need a test meter. Â the black probe goes on the Neutral and then the red probe goes on (suspected) live wire, if you see 240v, then you have perm live, if it's 0v but when the switch is thrown goes 240v, then that's your switch live.
This info is for a ceiling rose type arrangement though, without seeing what you want to test out, it's a little difficult to advise further.
You say you want to add a socket? Â I'm assuming a shaver or some such? Â You lighting circuit will most likely only be 6a so you shouldn't be putting 3 pin plug sockets on it, if that was your plan?
sorry I meant another light (in the adjoining garage) typing whilst looking after toddlers.
I have a multimeter. Â I take it I would have to disconnect the wires from the junction box to tell.
I have used a volt pen tester so I think I know the perm live but tbh I don' trust it as it indicates induced current all the time and there are socket circuits.in the vicinty
second question for some reason the earths are twisted around the outside/back of the junction box. Â second one I've found like this so not a bodge. Â there are enough pins in the box. Â maybe some old type of wiring practise? Â smaller brown circular junction box if that helps date it
Live tastes like chocolate.
Photo might be useful?
If you have a junction box, You should be able to test in situ if you remove the cover. Â Twisted earths aren't all that uncommon.
ok thanks. Â unfortunately no photo today as boards + carpet back down when kids came back from nursery. Â prob won't get a chance to take another look till the weekend now
Assuming from the sounds of your description you have a JB above the ceiling rather than a ceiling rose for the connections.
You should see a cable going to the light position.
Blue/black will/should be neutral and the Brown/Red in the same cable will be connected to switched live.
Follow the other cable connected to switched live and that will head to the switch - obviously the other core in this cable will be connected to permanent live.
If you have a rose, then it should be the middle three terminals.
Be careful about adding lamps to the circuit, it could already be to capacity. Twisted earth is common, get an electrician in and get rid; and while they're at it ask them to make additions to your lighting circuit
For your learning: the safest way is to isolate the circuit AND test that it's isolated at the junction box, i.e. no electricity present, there's no telling who's connected what in there. Google safe isolation and HSE GS38
Assuming twin and earth, visually work out which is likely to be supply, switch and lamp. Disconnect the switch cable from the box, join the bared L and N ends with a connector block, nip downstairs and test for resistance at the switch between L and N; should be almost 0
Repeat for the lamp
People are over complicating this. Use a proper tester, thay will show you have 230v present, not a screwdriver as they cant be trusted. Turn all the lights off in the house, and test to identify which cable is still live. That will be your permanent live.
Twisted earths are bad practice, and would be a c3 fault, meaning that Improvement is recommended. I'd untwist them, and put them in a terminal of the junction box, using earth sleeving. If you're not happy doing this, I'd get an electrician in to do it.
Thanks all.  Have had the board updated last year and the install passed the safety checks according to the sparky.
As I find the junction boxes ill tidy them and connect the earth correctly. Cant see why the original installer didn't take 30seconds to do it properly.
Without ripping up loads of tiles and boards I can't trace it back to the outlet. I reckon it's on of the downstairs kitchen lights which is under the bathroom
I also have a couple of light fittings with no earth at all so I'm replacing those when I find them.
All my bulbs are led so I would be really surprised if it would be anywhere nearcapacity. I have 8 pendants with 9w leds on this circuit
Have had the board updated last year and the install passed the safety checks according to the sparky.
No doubt. The problem for the sparky is accessing everything for a visual inspection, there will be a comment about this on the report. The conductor will test as being continuous and that it's insulated from other conductors, but it isn't best under fault conditions
It may be that twisting conductors together like this was considered acceptable practice 30 years ago, in the same way that RCDs weren't used
Blue/black will/should be neutral and the Brown/Red in the same cable will be connected to switched live.
Never assume the colour of the wire tells you anything definitive esp with lighting circuits where a switched live is concerned! At best it's just a vague indication of what it might be!
Multi-meter is the best way to check and make sure you test with all switch positions, so as to eliminate the switched live......