Ceiling Light

[matt1889]

Hi all

Not sure if this should be in the UK forum or not, I'm in Ireland so the wiring is the same from what I know.

I'm in the process of replacing a ceiling light which has never worked. Let's call this light C. Lights A, B and D-F worked fine up until this point.

I removed the light and replaced it with a new light, connecting the wires in the same way they were previously connected to the old light (although now I'm doubting myself!). This light works, as do A&B, but D-F don't turn on.

If I disconnect light C completely, Light A still works but B doesn't. Light A only stops working if I turn off the downstairs lights completely at the switch board.

The wires are all sleeved in grey so it's difficult to tell which should be live or neutral.

I've tested the voltage between wires:
Wires 1 & 2 = 240 volts
Wires 1 & 3 = 72 Volts
Wires 2 & 3 = 120 volts

However, if I turn on light B at the switch, this changes:
Wires 1 & 2 = 240 volts
Wires 1 & 3 = 0 volts
Wires 2 & 3 = 240 volts

Any advice please?
One thing I'm wondering, could another wire have slipped into the ceiling recess when I was removing the old light?

Thanks

 

[pete01]

If light A,B,D And F worked fine put them back as they were originally and post a pic of light C wiring.

Don't suppose you have a before picture, although it didn't work anyway did it

 

[ETAF]

One thing I'm wondering, could another wire have slipped into the ceiling recess when I was removing the old light?

yes
Did you take a photo of all the old connections in the light ?

The wires are all sleeved in grey so it's difficult to tell which should be live or neutral.

I guess you did NOT mark them with any tape at all

(although now I'm doubting myself!).

yep sounds like it

Did C light ever work ???

 

[matt1889]

yes
Did you take a photo of all the old connections in the light ?


I guess you did NOT mark them with any tape at all


yep sounds like it

Did C light ever work ???

I did mark them, with tape, and made a note of the original connections.

Light C never worked since we moved into the house.

 

[matt1889]

If light A,B,D And F worked fine put them back as they were originally and post a pic of light C wiring.

Don't suppose you have a before picture, although I didn't work anyway did it

I haven't done anything to any of the lights other than C.

I don't have a before picture but I marked them with tape before I removed them, and made a note of how they were connected. I'm just doubting my own sanity at this stage!

 

[pete01]

I haven't done anything to any of the lights other than C.

I don't have a before picture but I marked them with tape before I removed them, and made a note of how they were connected. I'm just doubting my own sanity at this stage!

Post a picture

 

[ETAF]

as pete01 says

If light A,B,D And F worked fine put them back as they were originally and post a pic of light C wiring.

 

[ericmark]

I would guess on:-
1 = Permanent Line
2 = Neutral
3 = Switched Line
The 72 and 120 volt are due to capacitive or inductive linking.
The easy way to work out line or neutral (they are both considered as live) is to measure to earth, in the UK 1966 was the last time a fixed wiring system was allowed to be run without an earth. The pendent does not need an earth, but everything else does, with fixed wiring. The odd one out is shaver socket, which does not have an earth, and non-fixed items can be class II needing no earth, but fixed needs a place to terminate the earth even if only tethered out of the way, the British regulations state terminate, so all fixed stuff should have a terminal to do that. In practice, we do see some grey imports, typically down lights, where the earth terminal is missing, but the earth wire should still be there.

 

[matt1889]

I would guess on:-
1 = Permanent Line
2 = Neutral
3 = Switched Line
The 72 and 120 volt are due to capacitive or inductive linking.
The easy way to work out line or neutral (they are both considered as live) is to measure to earth, in the UK 1966 was the last time a fixed wiring system was allowed to be run without an earth. The pendent does not need an earth, but everything else does, with fixed wiring. The odd one out is shaver socket, which does not have an earth, and non-fixed items can be class II needing no earth, but fixed needs a place to terminate the earth even if only tethered out of the way, the British regulations state terminate, so all fixed stuff should have a terminal to do that. In practice, we do see some grey imports, typically down lights, where the earth terminal is missing, but the earth wire should still be there.

Thanks - Yes, there are two earth wires which I didn't mention.

 

[matt1889]

OK - I managed to get some of the sheathing back, there is one brown (wire 1) and two blues (wires 2 & 3). I've colour coded them with wire 1 as brown, wire 2 as yellow, wire 3 blue.

When I wired the light originally, I had 2 & 3 feeding into the neutral connection and 1 into the live on the new unit on Light C,. As I said before, this meant that lights A-C worked but D to F don't turn on. If I disconnect light C completely, Light A still works but B doesn't. Light A only stops working if I turn off the downstairs lights completely at the switch board.

I tested all of the cables to earth on the Light C connection:
Wire 1 (brown) = 170v
Wire 2 (Yellow) = 66v (unless I turn off light B, in which case it's 0)
Wire 3 (blue) = 114v

Pictures attached of the wires and the connection on the light.

 

[SUNRAY]

This is what I would expect it to be with 1, brown=switched live - 2, loop out neutral -3, loop in neutral. However it appears you have an issue with you earth(s) which needs investigating.

 

[matt1889]

This is what I would expect it to be with 1, brown=switched live - 2, loop out neutral -3, loop in neutral. However it appears you have an issue with you earth(s) which needs investigating.View attachment 387335

Thanks - got this sorted with the earths, one of them wasn't properly inserted.

 

[SUNRAY]

Thanks - got this sorted with the earths, one of them wasn't properly inserted.

Thanks for the update.