Clicking noise at CU after replacing dimmer switch

[kinkyboots]

Hi

I've just replaced an old white plastic touch dimmer switch with a chrome one (yes yes it's earthed!)

BUT - When I press the switch I'm hearing a click coming from the CU (as it happens to be in the same room). It's not flicking the fuse off or anything but it's an audible click and I've never heard it make that sound before.

Also whereas the old touch dimmer switch used to buzz, this one doesn't really make any noise but the buzzing noise is now coming from the light fitting. It's loudest when the lights are on full and much quieter when the lights are dimmed - which is the opposite of what the old switch did.

The new switch is a Volex touch control dimmer switch - this one. The light fitting itself is one of those silver ceiling blobs (technical term ) containing a toroidal transformer, with a load of wires with small G4 capsule bulbs hanging off it (7 x 20W). I never noticed buzzing coming from the transformer before; it was always the dimmer switch on the wall that buzzed.

The leaflet that came with the Volex dimmer says:
Suitable for control of dimmable electronic transformers, toroidal (wire wound) transformers and tungsten halogen lamps WITHOUT de-rating.


So if this switch is allegedly suitable then why the loud buzzing and what's that click at the CU all about? Is this switch safe to use or should I remove it?

Thanks.

 

[ScrewForumIsJunk]

'Clicking' sounds at CU's can only be one of two things -

(a) the load is marginal for the MCB rating as in its a 6A MCB and the actual load is close to or over 6A. That is the total load is marginal. Check this by switching on as many lights on the same MCB as possible until its tarts clicking.

(b) its a faulty MCB at the CU.

Volex are just about the worst make of accessories that you can buy.

It is not the light fitting that is buzzing it is the transformer and its a very common problem.

 

[kinkyboots]

Hi thanks for your reply

With regards to the load - that was the only light I was attempting to turn on so it can't be overloading.

I have removed the dimmer switch from this room now. Went out after I made that post yesterday; when I got home I noticed the dimmer switch plate was hot to the touch - and the lights had been OFF.

Something obviously not right there - it wasn't playing nicely with that particular light/transformer. I've reverted back to the old switch in this room and put that dimmer in another room and it's fine. No clicking, no extra loud buzzing and it's not getting hot!

Didn't realise Volex was a bad make to buy... I've gone and replaced all my other switches with Volex ones today. D'oh!

 

[ScrewForumIsJunk]

"With regards to the load - that was the only light I was attempting to turn on so it can't be overloading." Sorry to disagree but it can be close to or exceeding the load with a single FAULTY light installation.

If its getting hot then clearly something really amiss. I suggest you get a sparky in (make sure he is registered as selv lights come under Part P). If that is not the answers that you want sorry but remote debugging of potentially dangerous conditions is no my scene.[/b]

 

[RF Lighting]

I'm wondering, with it being a cheapo dimmer that it is not suitable for dimming torroidal transformers.

Normally you need a special dimmer for this, which your old one may have been.

 

[kinkyboots]

"With regards to the load - that was the only light I was attempting to turn on so it can't be overloading." Sorry to disagree but it can be close to or exceeding the load with a single FAULTY light installation.

If its getting hot then clearly something really amiss. I suggest you get a sparky in (make sure he is registered as selv lights come under Part P). If that is not the answers that you want sorry but remote debugging of potentially dangerous conditions is no my scene.[/b]

You're scaring me now!!

It's okay though - as I said, I've removed that switch now. I am using it in another room but the lights are different - LV halogen lights with individual transformers rather than the light with the great big toroidal transformer. I think perhaps it was the transformer it wasn't getting on with.

I will keep an eye on the other room though and either remove it or call a sparky in if there are any problems. Seems fine so far. I was really cautious about making sure the lighting circuit was properly earthed beforehand so I called someone in to test it.

BTW I've only been changing switches and not added any new lights so the load hasn't changed.

I've just gone running round the flat like a mad woman turning all the lights on and off and not heard any clicking noises from the CU

I'm wondering, with it being a cheapo dimmer that it is not suitable for dimming torroidal transformers.

Normally you need a special dimmer for this, which your old one may have been.

I think you might be right. The leaflet enclosed with the switch did say it was suitable for toroidal transformers though - but something obviously wasn't right as it was hot all the time and buzzing loudly when lights on full and quiet when lights on low (opposite of what usually happens?!!)



Can anyone recommend a polished chrome flat-plate touch dimmer switch that would be suitable for use with a toroidal transformer? Thanks.