Buzzing dimmer switch with Low Voltage downlighters

[JDLDIY]

Hi there, my electrician has just installed 8 x 50w low voltage downlighters in my lounge and switched them from a dimmer switch. There is one transformer for each light and they are electronic ones stated as dimmable.

The buzzing noise is quite loud, my other half who isn't normally as fussy as me says she can't live with it. My electrician seems to think it's not a problem and hasn't come up with any solutions!

I've just done a search and seen something about "trailing edge" or something but it's a bit beyond me. Can I do anything to improve this situation other than replace the dimmer with a switch? Is there a more expensive dimmer switch which would help? We're also getting a buzzing from the lights themselves (I presume from the trannies) what can be done for that?

Many thanks

JD

 

[RF Lighting]

Would you be happy to unscrew the dimmer switch from the wall and then report back here with what is written on the back of the dimmer switch.

Make sure you turn the power off first.

 

[JDLDIY]

No problem at all, back in a bit...........

 

[JDLDIY]

OK, they are made by DETA. It is a 2 gang dimmer, the other circuit being for floor lamps. each dimmer says on it;
2 way 200-250V AC
Maximum load 400W
Minimum load 60W
BSEN 60669-2-1

Does that throw any light on it?

 

[RF Lighting]

Does that throw any light on it?

Yes

Maximum load 400W

This is the maximum load for a standard resistive load (like a light bulb*)

The dimmer maximum must be derated when it is used with ELV downlighters. (usually by 25%)

You will need a 1000W dimmer for all those lights, or alternatively you could use lower wattage lamps.

By swapping the 50W lamps for 35W lamps you would shed 120W of load, bringing your total down to 280W, which is fine for a 400W dimmer.

You will notice very little difference in light output between the 50W and 35W lamps.







*I know. You plant bulbs in the garden, you put lamps in lights.

 

[JDLDIY]

Many thanks RF. Is there an alternative by replacing the dimmer switch - I mean is there a higher rated switch available in 2 gang that will fit the square back-box? Also, just to add - why do I need a 1000W dimmer, can't I get a 600W one?

 

[RF Lighting]

standard dimmers that are 1000W are only available as 1G switches, as the heat generated by 2 switches side by side on a 1G plate would be too much.

The only dimmer I know of that will be ok is This. It is rated at 400W, but it is already derated for use with ELV downlights.

 

[JDLDIY]

Excellent, so just to confirm, I can use that dimmer and won't get the buzzing if I keep my 50W lamps? Costwise I may as well do that as replace all my lamps with 35W ones.

And I get to have another remote control in the room!!

Edit: I've just looked at the notes linked at the bottom of the TLC page and it seems to suggest that it won't do the job as I have 1 transformer per lamp.

 

[RF Lighting]

I have the very same dimmer loaded to 300W with ELV downlighters, and there is virtually no buzzing even when dimmed.

BTW you need to buy the remote seperatly, but they are only £4.75 + VAT, or alternatively if you have a couple of unused buttons on an existing remote this can be programmed into the dimmer.

 

[JDLDIY]

RF, sorry, I posted at the the same time as you, see my EDIT above. It also says in the notes that a maximum of 300W per gang should be adhered to. What do you think?

 

[RF Lighting]

I can't find this 300W limit. Where abouts is it?

Having 1 tranny per lamp will not make any difference, and is the standard way of wiring LV downlighters.

 

[JDLDIY]

This link http://www.tlc-direct.co.uk/Technical/DataSheets/Systems/TouchRemote.htm
mentions the "absolute limit of 5 transformers"

This link
http://www.tlc-direct.co.uk/Technical/DataSheets/Systems/DimmerGuide.htm
mentions the limit of 300W per gang.

Thanks for looking at all this for me.

JD

 

[JDLDIY]

What do you think guys, is it worth me risking it on this varilight dimmer or should I bite the bullet and get the switch changed to a 1 gang 1000W dimmer?

The electricians coming around tonight, hence the bump.

Many thanks

JD