installing a light fitting

[htid]

Ive moved into a new place and my room has no ceiling light but 2 wall lights both controlled by a normal light switch. I don't know much about electrics but I do know how to fit a light (usually). I did one and it was your straightforward live neutral and earth (was built in the 70s so red/black/bare copper). I came to the second and its got 3 red, 3 black and 2 copper. stupidly I cut the existing light away without looking exactly how it was already. I can see that there are 3 terminals in the light - one has 2 black, the second has 2 red and the third has one red and one black. The 2 bare copper ones are intertwined into a seperate terminal. Thing is I dont know which of black/red combo went into which terminal! Does it matter? can I just put any to any or is it just a case of trial and error, I assume blowing the fuse each time if its wrong?

Cheers

[GoNz0]

yep you will only blow the fuse if your wrong, the bare copper are the earth and should by law have the green/yellow sheath placed over them so this is a home bodge job already.


any chance of a pic to get a better idea ?

could well be the ring main passing through, black and red going to the switch (the black and red together will be the switch wire coming back from the switch.

you should have red and black with voltage from the ring main, a red wire from the ring main to the switch, in turn when the switch is on the black then has the the return ring main voltage and should by law have red tape on it to show its live (brown with new wiring) the black wire then joins the red that feeds the light.


you need a multimeter to figure out what wire is for where, pull the fuse to start

find out what red and black feed the switch by checking for closed circuit when the switch is on and open circuit when off. label those as switch.

then join the wires in the 2nd light fitting and find what wires are now closed circuit, label as 2nd light fitting.

you are then left with 2 wires from the ring main.

let me know what you have

[rox0r]

If you have a multimeter you can just bell out the switch wire to identify it, otherwise you're in for a bit of a giggle if you've chopped off any notion of tapings on the ends.

Edit: sneaky gonzo edit beat me to it.

[GoNz0]

so far i have edited it about 5 times lol. dont want him blowing himself up

sounds like its on a spur and not a ring or there would be 4 red and black with 2 earth.

[rox0r]

Indeedy, immediate gut instinct would tell me the lad needs a sparky round rather than trying to blunder through a potentially dangerous guessing game.

[GoNz0]

so long as his fingers are dry he will be fine

so long as he has a multimeter and pulls the fuse he can trace the wires without to much risk.

and making sure fuses are not nails

[rox0r]

I predict a lack of multimeter......

Here's hoping the OP has a PP9 battery and a willingness to stick his tongue on mains wires..... (As a responsible Hexus poster I DO NOT condone this manner of wire tracing no matter how many times I've done it, seriously leave it to morons like me)

[GoNz0]

so long as you crack the wires together 1st to rule out mains voltage its a fun way of doing it imho

[peterb]

It sounds as if it is a lighting ring main, so one pair with the earth will be one side of the ring, the other pair with the earth will be the other side of the ring and will be joined together at the ceiling rose connectors. The other pair will probably be to the switch (and should also have an earth to earth bond the switch). One side of that pair will connect to line (red) on the ring, the black will connect to the lamp holder, the other side of the lampholder will connect to neutral (on the ring).

So, the ceiling rose will have three connector blocks on it. One connector block will be for earth and will have 4 terminals (earth for ring in, earth for ring out, earth for switch and earth for the lampholder.

The line block will have three terminals, one for ring in, one for ring in, one for the switch.

Neutral block will have three terminal, one for neutral in, one for neutral out, and one for the lampholder. There will be a single terminal block for the switch return to connect to the lampholder. You must ensure that you are switching line, not neutral - otherwise one oin of the bayonet connector will always be live, even though the lamp is off. And if you are using edison screw lamphoders (rare in the UK) the screw is connected to neutral, the switched line to the centre terminal.

This is a typical arrangement, the exact layout may vary from rose to rose, but should be explained in the leaflet that comes with it.

If in doubt - get an electrician in.

[rox0r]

But in all seriousness though, please htid, if you're not sure about what you're doing...then leave it alone.

[GoNz0]

It sounds as if it is a lighting ring main, so one pair with the earth will be one side of the ring, the other pair with the earth will be the other side of the ring and will be joined together at the ceiling rose connectors. The other pair will probably be to the switch (and should also have an earth to earth bond the switch). One side of that pair will connect to line (red) on the ring, the black will connect to the lamp holder, the other side of the lampholder will connect to neutral (on the ring).

So, the ceiling rose will have three connector blocks on it. One connector block will be for earth and will have 4 terminals (earth for ring in, earth for ring out, earth for switch and earth for the lampholder.

The line block will have three terminals, one for ring in, one for ring in, one for the switch.

Neutral block will have three terminal, one for neutral in, one for neutral out, and one for the lampholder. There will be a single terminal block for the switch return to connect to the lampholder. You must ensure that you are switching line, not neutral - otherwise one oin of the bayonet connector will always be live, even though the lamp is off. And if you are using edison screw lamphoders (rare in the UK) the screw is connected to neutral, the switched line to the centre terminal.

This is a typical arrangement, the exact layout may vary from rose to rose, but should be explained in the leaflet that comes with it.

If in doubt - get an electrician in.

don't confuse matters, there isnt a ceiling rose in play yet, that will be a 2nd spur

sounds like a row of connector blocks making things difficult without a multimeter to find out the switch and 2nd light leaving the mains.


fair enough i do jobs like this live but i know what i am doing

[rox0r]

I'd be happier to see the OP make a post so we know he hasn't blown himself to kingdom come in the meantime

[GoNz0]

i put a fiver on blowing the main fuse and being unable to locate it in the dark

[htid]

Ok most of that went over my head and I have no multimeter so I guess its best not to risk it. I was just going to buy buy a load of fuse wire and try every combination, blowing the fuse every time as I went until it worked. very weak signal here so can't upload a photo until tomorrow when im out with better signal.

[htid]

i put a fiver on blowing the main fuse and being unable to locate it in the dark

Haha im not that stupid

[peterb]

Ah, my bad, I thought he was removing the walllights and fitting a ceiling rose...

Definately multimeter/neon screwdriver time!