--------Downlighter fault!!---------

[Judd]

I will try to explain this as best as I can,
Wired 18 downlights in two rows of 9,
The downlights were wired in 3core and earth cable so two switch wires could be used to switch the downlights however the customer wished. It was opted for the lights to be switched in banks of two on alternating switch wires (hope that makes sense)
So the problem is ALL the lights turn on regardless of which switch wire is on (with the other off) The lights do seem slightly dimmer on the switch wire that remain off.
The downlights used are cheap LAP LED fittings bought by the customer,
The run is quite long from the switch to the last fitting.
I/R between switch wires >200M
47V coming back on switch wire that is off when other switch wire is on voltage decreased to 25v when half the downlights were disconnected.
Any help?
I'm thinking potentially induced voltage from 3core? would installing different fittings remedy the situation?
Thanks

 

[MJPD29]

Induced voltage from 3 core is highly unlikely I would have thought as this method is used for all manner of lights including emergency fittings without issue. If you are absolutley certain the Cabling has no faults and your connections are correct I would remove the fittings and see if the voltage still appears on the other core.

 

[telectrix]

replace 1 GU10 on each string with a halogen lamp. if the problem disappears, then it's induced/capacitive voltage in the 3 core.

 

[Dustydazzler]

Exactly, remove lamps and try with an old halogen bulb , if that don't work remove lamps and test voltage between phases and N on the cable with a good volt meter.

 

[123]

Are these dedicated LED fittings or are they GU10 fittings?

Have you mixed the connections up somewhere between a switch wire and a neutral perhaps?

 

[Judd]

Are these dedicated LED fittings or are they GU10 fittings?

Have you mixed the connections up somewhere between a switch wire and a neutral perhaps?

They are sealed type LED dedicated downlights, no all connections are correct

 

[Deleted account]

This has occured with me twice.

Both times with 2way lights.

on one I had g9 bulbs. I swapped them for another make of G9. All fine. it was the cheaper make of bulb that worked. So price doesnt count for much.

the second time not so lucky. Integrated lights. I had to replace them with another make.

 

[Pretty Mouth]

I think a break somewhere on the neutral might cause this problem.

You have 3 conductors L1, L2 and N.
Say L1 is switched on 230V, L2 switched off.
Lamps on L1, upstream of the break in the N will complete the circuit normally
Lamps on L1 downstream of the break in the N will complete the circuit like this:

• through L1
• through lamp(s) on L1 downstream of the N break
• through the N downstream of the break
• through lamp(s) on L2 downstream of the N break via their N
• through L2
• through lamp(s) on L2 upstream of the N break
• through N upstream of break to CU

So all lamps on L2 will see some voltage

 

[Judd]

I drew the diagram out for this so I could understand it easier and yes its definitely likely as the neutrals on the fittings aren't hard fixed and are magically looped somewhere under the cover of the fitting, just trying to think of the best way to test this theory?
Disconnect all fittings from one of the strings and temporarly link them and if there is a neutral break down no lights will illuminate??

I think a break somewhere on the neutral might cause this problem.

You have 3 conductors L1, L2 and N.
Say L1 is switched on 230V, L2 switched off.
Lamps on L1, upstream of the break in the N will complete the circuit normally
Lamps on L1 downstream of the break in the N will complete the circuit like this:

• through L1
• through lamp(s) on L1 downstream of the N break
• through the N downstream of the break
• through lamp(s) on L2 downstream of the N break via their N
• through L2
• through lamp(s) on L2 upstream of the N break
• through N upstream of break to CU

So all lamps on L2 will see some voltage

 

[Pretty Mouth]

I drew the diagram out for this so I could understand it easier and yes its definitely likely as the neutrals on the fittings aren't hard fixed and are magically looped somewhere under the cover of the fitting, just trying to think of the best way to test this theory?
Disconnect all fittings from one of the strings and temporarly link them and if there is a neutral break down no lights will illuminate??

If I've understood you correctly, the lights upstream of the break will still come on, but downstream would not illuminate.

You wired this yourself, so you know the route the cable takes? You might be able to pick up the break with your volt stick, depending on its range, without disconnecting anything.

Live test, 1 switch on, the other off.

At the supply end of the 3 core cable, the neutral will be at about 0V to earth, so should give no indication on your volt stick. After the break, it will be somewhat above earth voltage, so may well light up the volt stick.

So start at the supply end, testing the neutrals as you go out, until you find the first neutral that lights up. If it doesn't work, turn the switch off, and the other on, and try again.