LED downlights dim when kettle switched on..

[a-z electrics]

Haven't seen this one before.. a string of 8 dimmable downlights in the lounge (max total load 40W) on a Hamilton LED dimmer ((LED-IT B) dim slightly when a decent load is switched on eg kettle. Then goes bright again when load off. Dimmer works fine on its own knob..
New build house, wired and tested by myself, different rcbo circuits.
Can anyone explain why/how this can happen!?
I haven't done many trials of which loads and circuits do it but I'm going back in a couple of weeks to do other work too, maybe try change the dimmer module?
I dont think any other rooms do it but not many are on dimmers. There are 3 outside lamps on the other dimmer switch next to the offending one and these seem ok..

 

[SagaCU29]

Haven't seen this one before.. a string of 8 dimmable downlights in the lounge (max total load 40W) on a Hamilton LED dimmer ((LED-IT B) dim slightly when a decent load is switched on eg kettle. Then goes bright again when load off. Dimmer works fine on its own knob..
New build house, wired and tested by myself, different rcbo circuits.
Can anyone explain why/how this can happen!?
I haven't done many trials of which loads and circuits do it but I'm going back in a couple of weeks to do other work too, maybe try change the dimmer module?
I dont think any other rooms do it but not many are on dimmers. There are 3 outside lamps on the other dimmer switch next to the offending one and these seem ok..

I would check the incoming voltage under load.

 

[pc1966]

What is the PSSC at the incoming board?

LEDs are usually less sensitive to volts than filament lamps are, but no idea if some dodgy dimmer might amplify and changes.

Best case is it is just down to a high supply impedance at the end of a long DNO cable.

Worst case is a bad joint somewhere as that could become a fire hazard.

 

[Midwest]

I was thinking of a loose connection at DB or before.

 

[a-z electrics]

What is the PSSC at the incoming board?

LEDs are usually less sensitive to volts than filament lamps are, but no idea if some dodgy dimmer might amplify and changes.

Best case is it is just down to a high supply impedance at the end of a long DNO cable.

Worst case is a bad joint somewhere as that could become a fire hazard.

I would have to dig out the paperwork but I if i remember correctly it was around 2kA.

 

[pc1966]

2kA is a fairly stiff supply, a 13A load would only cause about 1.5V change which is well under 1% and unlikely to be noticeable on LEDs.

I would be checking for any loose connections or changes in the supply characteristics.

Have they recently had a smart meter fitted or similar?

 

[Lucien Nunes]

if some dodgy dimmer might amplify any changes.

This. Some combinations of 230V dimmer and LED are ridiculously sensitive to both voltage variations and waveform distortion. They might give a reasonable impression of dimming smoothly, but interact with each other and with other loads.

For example, we put some into one of our mobile units, they worked fine on normal mains, but when running on a good sized genny (100kVA) putting out a reasonably steady 230V they were all over the shop, bright, dark, sometimes flashing on and off. Changed the dimmers to a different flavour, this time they weren't doing anything crazy by themselves but started dimming unacceptably when the aircon or projectors fired up, even though the voltage drop was reasonably within spec.

Not sure there is any reliable way to validate a pairing of lights and dimmers without thorough testing and experience of the products.

 

[a-z electrics]

I would have to dig out the paperwork but I if i remember correctly it was around 2kA.

why would it just affect the dimmed lights though?

 

[a-z electrics]

2kA is a fairly stiff supply, a 13A load would only cause about 1.5V change which is well under 1% and unlikely to be noticeable on LEDs.

I would be checking for any loose connections or changes in the supply characteristics.

Have they recently had a smart meter fitted or similar?

they did have the solar pv guys in connecting the panels, since I did the installation testing..

 

[Zerax]

Not sure there is any reliable way to validate a pairing of lights and dimmers without thorough testing and experience of the products.

Agreed... dimmers and LED lamps are one of my pet hates !

 

[pc1966]

Simple check is to put a meter on a different circuit to the kettle (so you see the supply volts), switch the kettle and see if the LEDs change and if the meter reading is anything like a justifiable shift. If volts stable then its a dodgy dimmer/LED combination.

 

[a-z electrics]

Simple check is to put a meter on a different circuit to the kettle (so you see the supply volts), switch the kettle and see if the LEDs change and if the meter reading is anything like a justifiable shift. If volts stable then its a dodgy dimmer/LED combination.

ok thanks, will try this next time I'm there.. also take a different make of dimmer module too.

 

[static zap]

Bring back , nice big smoothing chokes , full of copper and stop putting it in cars.
(an old man-from a different ERA comment - Valves had HT chokes)
..none of this sitting on the crest of a wave.. 2% duty cycle