Hi
when using dimmer are any of you guys familiar with d-rating them when using standard 50 watt halogens my wholesaler reckons the BG ones by 25% , i recall having to do it with the energy saving halogens but not gu-10 i would have thought they were resistive only ??

I always like to de-rate dimmers by 25-50% when feeding halogens, I don't see any reason to do it with energy saving lamps though,

Dave.

It was the candle type bulb with a halogen capsule inside that i was told to de-rate .
do you de-rate them for personal preference or manufactures info? and why is halogen different than a standard filament jus curious

I'm not really sure of the reason mrcornbeef, it's just something I read in the early days of fitting downlights and dimmers do seem to fail quite regularly when feeding halogens, even when they are downrated. There is something about some GU10's having an internal fuse which helps prevent dimmers failing when the lamp blows but i'm not sure how we know which ones are fused and which are not! ( I think I did find out once but can't remember now!)

Dave.

Evening all,
GU10 lamps and the new halogen energy savers that look like the old incandescent lamps,especially cheap ones are taking dimmers out due to the high current draw that occurs when the filament starts to break commonly when turned on(we are talking milli seconds here and I apologise if I am appearing to teach you all to suck eggs but bear with me please) but,it occurs mainly to dimmers that are push on\off rather than rotary on\off.
If the lamps are on normal switches then the 6A breaker trips but dimmers being as carp as they are act as an intermediate fuse.
I have over the last few months,fitted only rotary dimmers, as this problem is driving me crazy with my elderly customers. Still using the cheap lamps
I have not had hardley any calls so now all I fit are rotary dimmers.Time will tell!!!
Regards
Antric

I think the other advantage of using a rotary dimmer with standard filament/halogen bulbs is that the bulbs are gradually brought up to the desired brightness setting.

Rather than coming on at the previous/random setting with push on-push off dimmers.

I suspect the rotary ones prolong the lifespan of the bulb as the filament isn't shocked on from cold to a high brightness setting.

Incidentally, older-style traffic lights used to have the filaments of each bulb kept warm with a trickle current when the respective lamp wasn't on. This prevents early bulb failure due to multiple on/off switching cycles. I believe modern traffic lights now use LED clusters.

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M.I.E.T - Forfeited this due to The I.E.T's ridiculous membership rules!

Soft start dimmers also extend lifetime of the bulbs, and you can buy ones which do not need de-rating.

As for BG dimmers, without de-rating they won't last long with mains voltage halogen bulbs.

Some of Aurora dimmers have small barrel fuse which prevent dimmer from damage in case of high currents caused by blowing bulbs.

I try to avoid BG dimmers as I found them not reliable, my preference are ones made by aurora or hamilton.

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Max

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