Wiring of ceiling light-help please!

tomstickland

I see that there are 4 terminals
L - live
E - earth
N- neutral
what's the fourth. Could that possibly be the lamp switched supply? Or is it a duplicate Neutral?

Sadly the wires photo doesn't tell me anything useful apart from that you have two cables coming in.
Any idea where the cables go? Options are:
from lighting ring, to switch, to another light.

You have to apply logic to find the solution. I don't have enough info at the moment. Where are you located?

djohn2002uk

Please dont put the 2 blacks together without testing it first. If the one black is the switched live then you are going to get one almighty bang.

YorkshireBoy

There's only 2 possible solutions for this situation (and they've both already been suggested I think)...

Solution 1
2 x red into the 'empty' terminal, 1 x black into the 'L' terminal (this should be the one that comes back from the switch and have a red tag on it), and 1 x black into the 'N' terminal.

Solution 2
However, if this ceiling fitting is the first of two on the same circuit (ie, the other is slaved off this one) then it's simply 2 x red into the 'L' terminal and 2 x black into the 'N' terminal.

Obviously, the earths go to the 'earth' terminal(s)

There are no other solutions for 2 cables/one light.

YorkshireBoy
(Electrical Engineer)

simonhgreen

Hi Guys

The 4th terminal is called "loop".

The lights (I have 2 in the room) are operated separately, the one that works fine is on a normal on/off switch, the one that's giving me nightmares operates on its own dimmer switch.

I assume the 2nd cable is to the lighting ring, but really don't know. If it does go to another light/the ring, would that not affect other lights (there doesn't seem to be an effect on any other lights)?

Location wise I'm in the South Wales valleys, but I think the wiring here is the same as everywhere else!!

Thanks

djohn2002uk

You can check it this way.
Switch everything off first.
Put the 2 Reds in with the brown.
Put 1 black in with the blue.
Keep everything else clear.
Switch back on.

If the light now works but with no control from the switch, then you know the black is the Neutral. If not then swap the 2 blacks and if it now works, that black is the neutral.

Switch everything off again.

Leave the black where it is.
Swap the other black with the 2 reds.
Put the 2 reds in the spare terminal on the block.
Switch back on.

If it is wired conventionally it should now work. If not you need to get a spark in to check it out.

This just repeats what mx-3 posted earlier but does prove the neutral.
I repeat again. Do not under any circumstances put the 2 blacks together without proper testing.

I've just seen your new post and it looks normal then so should work as above but the warning is for real now.

tomstickland

This is why I asked about the 4 terminals though. Edit: it's loop.

Try following the wires in the fitting itself. Which 2 terminals is the bulb connected to?

YorkshireBoy

Just a thought...whilst dimmer switches have a maximum wattage, they also have a minimum wattage below which the dimmer won't function properly. Have you increased/reduced the connected wattage significantly?

BTW, from what you've now said, you should wire it up as in my solution 1, and adopt djohn2002uk's procedure for identifying the switch wire and neutral - and then tag it with red insulation tape if you have some.

simonhgreen

Hi guys

I am going to leave it until the morning and will go through all the suggestions 1 by 1.

I'm seriously grateful to all who have contributed and will update the thread tomorrow if I am:
a) in the light
b) in the dark
c) dead

Have a great night and happy NY to you all.

Cheers

tomstickland

South Wales valleys? I have a friend who lives up near Abercarn.

simonhgreen

Hi guys

Mission accomplished, I have light!!

It turned out the almost throwaway remark by Yorkshire Boy regarding the dimmer switch was the root of the problem.

Although it said it's maximum capacity was 400w (the new light is half that) when I swopped it for a normal on/off switch it worked first time.

I'm now going to buy a new dimmer switch and see what happens - I know the wiring is OK now.

Many, many thanks to all who contributed and saved me a fortune in call out fees (NY Eve - I go cold thinking about it).

I know some of you are professional electricians, so a special thank you for your help.

I also think you do your profession huge credit by helping no-hopers like me.

Cheers (until the next time!!!)