LED downlight issue 1x keeps cutting out

[Elliott96]

Can any one help?
Just been to a customers house and in a loft extension there are 6x LED downlights (cob). The last downlight in the circuit seemed to be cutting out when the dimmer was at the minimum so I replaced the standard LED for a varilight dimmer so the minimum could be adjusted slightly. Even after this, when the dimmer is switched off, adjusted to minimum and switched back on that one downlight in the circuit seems to stay off. Any ideas? Maybe volt drop?

 

[Wilko]

Hi - maybe the lamp itself is a bit odd. If it was easy I'd try moving it and see if the fault moves to the new location ...

 

[Elliott96]

Hi, thanks for the reply i have tried this, they are the cob downlights with the fixed lamp but i still moved it to a different location and the same thing still happened at the end of line so it isnt a lamp issue by the looks of it, i could understand if it was 50 downlights but with just 6 i cant see why‍

 

[westward10]

Fit a temporary batten at the last one and see what happens.

 

[littlespark]

Last one on the line?
Simple loose connection between it and second-from-last? Could be on line or neutral.

 

[static zap]

Last one on the line? ....

Yep classic overthinking it -- Look for simple solution 1st !

 

[Rpa07]

How many times have you adjusted the varilight dimmer? . Try adjusting the minimum until it doesn’t go wobbly!
After checking for poor connections first.

 

[Midwest]

As Rpa07 said. You could be just adjusting the luminaires to below their minimum, they are happy to turn back on at.

 

[Elliott96]

I checked for loose connections and all seemed fine, i spent a while setting up the varilight dimmer with different minimum brightnesses and also tried changing the “driver mode” on it, i set the minimum brightness just off the maximum so there was barely any dimming actually happening and the same still happened... turned the switch off and back on and that same one didnt kick in untill the dimmer was turned up slightly!

 

[static zap]

Un-thinkable .. could you make it a ring / centre split radial!
(if too close to the limit no go will become random , or temperature dependent.)

 

[Elliott96]

Static zap i was thinking that but its a loft conversion so not going to be a easy job, for the sake of one light i think the customer will say leave it...

 

[littlespark]

Think about it logically. Its always the last on the line that is at fault? And its not the fitting itself 'cos you've swapped them about.
Not a loose connection, you say you've checked.

It must be a damaged cable between last and second from last position.
Do you know which fitting is second from last? It might not be the one you expect.
Disconnect all the lights and check for continuity, and IR.

It all takes time, and it is up to the customer if they want to pay for it or just do without the last light.

 

[Rpa07]

If it is COB GU10 then you may have to try a different make at least to eliminate the lamps themselves.
I like @static zap idea of a ring or split radial but as the horse has bolted and decoration is final then other ideas are needed.

 

[static zap]

(Build a rig -independent of setup -to measure each lamp , check they all have near identical draw , keep the frugal , swap out any thirsty ones)
..They are sure to be near identical if you test them..(sods law)

 

[Elliott96]

Thanks for the responses will try this if the customer calls back.