Dimmer Selection Wisdom

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Hello,

I wonder if someone can help me here.

My understanding is :

Leading edge dimmers are suitable for mains GU10 halogen lamps, but need to be down rated 75 to 50% to cover the load.
Leading edge dimmers are not suitable for GU5.3 / Mr16 low voltage lamps.

Trailing edge dimmers are suitable for both GU10 halogen and MR16 (with electronic transformers) and don't need to be down rated.
Trailing edge dimmers are preferable to leading edge as they have soft start and overload protection.

My questions are:

Are there common characteristics where you can identify a trailing vs. leading edge dimmer by looking at it ?
I see that some trailing dimmers have a slight L shape to them (the bottom of the L containing the coil), but this doesn't seen to be universal.

I recently replaced a 400watt dimmer which was controlling 9 x 50w mr16s.
The dimmer looked like it's been there a long time, and looked to be leading edge (not L shaped).
obviously, when I installed the new trailing module it went into protection mode,
until I removed 1 x lamp, bringing it down to 400 watts.
i advised the client to replace the lamps with 35W ones to give some leeway and allow him to replace the 9th lamp.
The client didn't do this and dimmer failed after 2 weeks.
This seemed strange as it wasn't overloaded and in a 35mm backbox with space.
But may have overheated as it's a two gang dimmer.

My thought is to down rate the lamps to 35W a piece and replace the 400W trailing dimmer (400w iQ Push on / Push off Dimmer Switch Module)

Am I just plain wrong in thinking you can't use a leading edge dimmer on Low voltage lighting, say a 1000w module for this arrangement ?

I think the client would be happier if he could stick with 50W lamps.

Any advise would be appreciated.

Thanks a lot,

Alex

 

[Octopus]

Or install a 1000w unit?

 

[scanner]

Hi Murdoch,

Thanks for the reply.
Can you recommend a suitable 1000w dimmer for low voltage lights ?

Thanks,
Alex

 

[telectrix]

me dad used these for dimming 100,000watt searchlights , 1943

 

[telectrix]

dunno where the puppy came from. must have pressed a wrong --- somewhere.

 

[scanner]

Love the airborne dimmer !

Who cares where the puppy came from, I feel better about the dimmer problem already : )

 

[Marvo]

Yeah, you can't beat a random dog post once in a while and it's good to see you're taking care of your nails Tel. :28::winkiss::sailor:

 

[telectrix]

nah, thet're 'er indoors' nails. these are mine:

 

[Richard Burns]

You have the information about dimmers correct, generally electronic transformers will need a trailing edge dimmer to control the dimming properly.
You cannot really tell by looking what type of dimmer it is, unless it is labelled leading /trailing edge!
Having a dimmer at maximum rating in a double dimmer situation will probably have pushed the dimmer into overheat, a lot of them have protection and will recover after a while, but would not be suitable for continued use.
A more complicated resolution, and more expensive, would be to replace the 12V lamps/transformers with 230V dimmable LED lamps and an LED dimmer.

 

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Thanks for the helpful post Richard,

I have a Selectric (?) 1000watt dimmer,
I'll give them a call tomorrow to confirm they're suitable for LV lights
and install it on Tuesday.

If it fails I'll advise down rating the lamps and go back to a Varilight 400watt dimmer
running under maximum.

Thanks for the posts... and the puppy photo : )

Al