"John Robertson" wrote in message
...
On 2017/06/26 9:52 PM, Phil Allison wrote:
John Robertson wrote:

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When they are RUN at the rated voltage and power. If you dim them the
tungsten is deposited on the quartz and short of heating the quarts to
white hot (above poster's remarks) the tungsten is going to STAY on the
quartz, not recoating on the filament.

http://www.topbulb.com/blog/dimming-...halogen-cycle/


** That is merely one person's opinion, not backed up with evidence.

Wiki says differently :

https://en.wikipedia.org/wiki/Haloge...on_performance

Stage lighting uses dimming all the time with halogen lamps and there is
no blackening or short life experienced - the lamps run much longer as
expected.

The claim that the "halogen cycle" puts metal back on the filament is
true but it does not deposit it back where it came from so has little
effect on lamp life.

Most halogen lamps are low voltage or high powered - so in both cases the
filaments are thicker than typical non halogen examples.

Having a thick filament makes a halogen lamp last longer.



..... Phil


Well, I must confess I've never studied halogen bulbs on dimmers but
reading Lutron's site does not give any concerns from them about halogens
on dimmers in household use:

It seems fairly obvious that a dimmed filament doesn't gas off much
tungsten.

Ordinary bulbs above a certain rating are banned and have been replaced by
halogen capsules enclosed in a regular globe envelope.

So far; I've not seen any dimmable CFLs on the shelves and LED bulbs are
probably more tricky. The packaged halogen capsules are the easy way out if
you want a dimmer.