Help needed on a dimmer switch problem.

[golum]

Hello members.

Just wondering if anyone can help me with some information on a dimmer switch please as I can’t seem to figure it out no matter what I try?

I have a 3 gang dimmer switch, 60 - 400W, 230V a.c.
Circuit 1 = 5 x 35W down lights. Each light is fed from 12 volt transformer.
Circuit 2 = 5 x 35W down lights. Each light is fed from 12 volt transformer.
Circuit 3 = 4 wall lights (dimmable) with 2 x 20W lamps on each patress and these are also fed via a 12V transformer that are concealed in the lights enclosure.

The problem I am having is circuit 3 (the wall lights) is perfect when on full load but when they are dimmed (even slightly) a loud buzzing comes off the transformers (not the switch) within the enclosure and the lights flicker. I thought this might have been as the minimum power was not met and thus tried putting all 3 circuits on one gang but this did not change anything. Circuit 1&2 = no problem, Circuit 3 = headache.
Is there something that I am overlooking or has anyone else had this problem?
Do the 12V transformers change the total load power?

Thanks in advance for any replies as I have now ran out of options?

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[chrish_1977]

Are the downlighters transformers dimmable?
Switch dimmers will sometimes buzz, how loud are we talking when it does buzz

 

[Guest112]

agreed depends on the fittings can you retrieve one of the transformers for further investigation~??

 

[golum]

Like I said Before the downlights are working perfect? It is just the wall lights that are playing up. All of the circuits/lamps are on the 12V transformers but the wall lights just make this loud buzzing noise and the lamps are flickering?
Seems weird?
There is a faint buzzing coming from the switch plate but that is normal and have encountered this before in several other jobs I installed.
The buzzing coming from the wall light transformers is very loud to be honest. too loud.

 

[TaffyDuck]

Had the same recently with these daft trick lights. Turned out that the transformers in the lights were vibrating against the metal casing.

Sort of solved it by taking the transformers out, and reseating them with 20mm grommets between them and the light and changing the dimmer to a trailing edge one.

Apparently common on certain Next light fittings so Im told.

Common problem apparently but a pain to sort out. Can take hours

 

[golum]

It took hours checking every termination and even changed the switch plate but did not change anything.
I can see the logic in your post Taffyduck, shall try that and reply if it works. Thanks again for time.

 

[nickpearson88]

Check transformers are dimmable, also check load rating doesn't exceed rating of the dimmer switch

 

[TaffyDuck]

Check transformers are dimmable, also check load rating doesn't exceed rating of the dimmer switch

Well tbh I assumed that this was already done.

 

[golum]

Yea, transformers can be dimmed. The dimmer switch is rated 60 - 400W each gang. On circuit 3 (wall lights) there is 2 x 20w lamps = 40W per unit. 4 wall lights = 160W total load. This circuit has met the minimum load and well under the maximum 400W load.