help with led dimming issue

kry221188 · Feb 25, 2016

I am a fully qualified electrician and have been in the trade for about 8 years

I have recently done a job where i fitted a 3 gang dimmer switch
one new feed into the switch
and 3 switch wires out

the issue is that when the 9 led spot lights are being dimmed
the other light fitting on a separate switch wire sometimes flickers or dimms slightly

i haven't come across this before and would be grateful of any help/ tips to resolve the issue

the dimmers are aurora and generally i haven't had any problems with leds before on these dimmers.

many thanks

karl

Darkwood · Feb 25, 2016

Welcome to the forum

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I take it we can assume all connections have been checked for tightness and good contact including upstream of the switches?.. The effected lights, are they also on dimmers?

kry221188 · Feb 28, 2016

thanks for the response
yes have double checked connections
and yes its a 3 gang dimmer switch.
although one is a dummy dimmer so just works as an on off switch but that switch wire is fine
its just the 2 switch wires that are on dimmers seem to affecting one another.
really weird.
when one is on full capacity (a sinlge pendant with led bulb) and then you dimm the spot lights it affects the pendant slightly.

1Justin · Feb 28, 2016

If supply to the switch is from a loop-in at ceiling, and there were a high resistance neutral from to the feed-off rose?
(Since we don't "conventionally" measure neutral resistance with just R1+R2, this could go unnoticed, - measuring "Rn+R2" can be a good idea

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Chopped mains from one dimmer would modulate the neutral. Say Neutral had 500 ohms between the loop-in and the dimmers. The main ~7 Watt LED (taking ~ 30mA) was the main lamp. This could modulate the neutral with perhaps ~ 15 Volts of chopped switching signal when the main lamp was dimmed, which would be enough to influence the other lamp sharing the same neutral.