Dimmer Switch Question

zom247 · 15 Sep 2016 at 17:08

My wife likes this light:

http://www.next.co.uk/g531162s4#991221

On the site it says "Halogen lightfittings may only be dimmed using a Next halogen compatible dimmer". The only dimmer I can find on their site is a touch one at £28. Do I have to buy this one to use or will any generic one from a diy store be fine?

Minstadave · 15 Sep 2016 at 17:10

Sounds like BS but makes you wondered why they have suggested it.

AHarvey · 15 Sep 2016 at 17:29

why not go to wilkos, but one for a couple of quid and test it first to see if they are talking rubbish

GeForce · 15 Sep 2016 at 17:53

For low voltage halogen you need a trailing edge dimmer as opposed to the more commonly used leading edge.

Reason for this is because you're chopping the waveform on the primary side of the low voltage transformer.

It doesn't have to be NEXT specific but it does have to be trailing edge, assuming the transformer in the fitting isn't something unusual.

zom247 · 15 Sep 2016 at 18:03

GeForce said:
For low voltage halogen you need a trailing edge dimmer as opposed to the more commonly used leading edge.

Reason for this is because you're chopping the waveform on the primary side of the low voltage transformer.

It doesn't have to be NEXT specific but it does have to be trailing edge, assuming the transformer in the fitting isn't something unusual.

Thanks, I'll have a look for a trailing edge one then.

thezappa · 15 Sep 2016 at 20:57

GeForce said:
For low voltage halogen you need a trailing edge dimmer as opposed to the more commonly used leading edge.

Reason for this is because you're chopping the waveform on the primary side of the low voltage transformer.

**Thread hijack, but kind of related**
So the LED bulbs in my living room which are 9.5W are flickering every now and then. I've understood what I've read to be because of the clipping that goes on so would a trailing edge dimmer be the solution or can a transformer be installed behind the switch or do I need to find another dimmer that supports a minimum wattage of 9.5 or less?
I have a 2 gang switch controlling 1 bulb each (in case that makes a difference)

Simon42 · 19 Sep 2016 at 09:41

Have a read of this: https://www.mkelectric.com/en-gb/Products/WD/LEDdimmer/Documents/MK%20Dimming%20Compatibility%20Guide.pdf

With all the variations on load and move to LED its a real pain for dimming these days. I've started using the MK Logic K1523WHILV and K1524WHILV dimmers and they've been fine for all purposes and allow me to use any type of bulbs over a good variety of loads.

Even with those dimmers I've read of some people complaining of buzzing with some bulbs but they've been the quietest for me on all bulb types especially LED and dim low wattage bulbs well.

GeForce · 19 Sep 2016 at 09:48

thezappa said:
**Thread hijack, but kind of related**
So the LED bulbs in my living room which are 9.5W are flickering every now and then. I've understood what I've read to be because of the clipping that goes on so would a trailing edge dimmer be the solution or can a transformer be installed behind the switch or do I need to find another dimmer that supports a minimum wattage of 9.5 or less?
I have a 2 gang switch controlling 1 bulb each (in case that makes a difference)

Sorry missed this post.

Are they mains voltage LEDs or low (12V) voltage?

If they are mains then a trailing edge wall dimmer is likely to sort it out (I guess you have a leading edge one at the moment).

If they're 12V then a trailing edge dimmer ought to do the trick, but the problem is that there's a transformer between the dimmer and the fitting, and they can respond weirdly to dimming. If you can get the model of the transformer I might be able to help you further, but your only option in the end may be to replace the transformer with a dimmable transformer specifically for LEDs, which will state which kind of wall dimmer you should use with them.