Author Topic: Just a question  (Read 917 times)
eyecandescent
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Just a question « on: December 20, 2022, 04:18:12 PM » Author: eyecandescent
So... I just wanted to ask, since I've received incredibly conflicting information from Lutron, and even several pages on the Internet.

I operate almost all of my lighting on dimmers, whenever possible, and use a lot of Incandescent & Halogen Bulbs. I especially like being able to slow-start and operate them dimmer than capacity, to keep them going far longer than their rated life.

My question is... and I'm hoping some of you can answer with a common consensus... is the use of a Dimmer really bad for the Halogen Bulbs? I've been told the use of a dimmer actually severely cut down their life, which was incredibly disappointing information. However, the user's guide from my Dimmers, suggests otherwise, and there is lots of conflicting information online  ??? .  I just want a more concrete answer.
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sol
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Re: Just a question « Reply #1 on: December 20, 2022, 06:03:59 PM » Author: sol
Glad you asked for I am wondering the same. Someone will chime in with an answer.
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AngryHorse
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Re: Just a question « Reply #2 on: December 20, 2022, 06:20:22 PM » Author: AngryHorse
Halogen can be confusing here, yes at some point when the halogen cycle stops working it may blacken the tube wall, but running them back upto full power usually clears it, James has a video on his site of this happening, although I have not seen this happen myself while dimming halogen lamps, I guess it’s dependant on the manufacturer?
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eyecandescent
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Re: Just a question « Reply #3 on: December 20, 2022, 10:27:16 PM » Author: eyecandescent
Do you think, this interferes with the life of the internal filament? I'm not even concerned about the blackening of the tube wall, as much as I am concerned about the life span.

I just want to read by and live-by incandescent for as long as possible, and consider dimmers to be the magic solution to my problems.



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Medved
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Re: Just a question « Reply #4 on: December 21, 2022, 03:26:39 AM » Author: Medved
It depends on the exact lamp design and even its operating position, how hot all the parts of the lamp operate and on the exact dimming level range. Usually the range of 20..100% of power is safe, it is just the "barely glowing red" levels, where the dimmers may actually hurt the lamps.
It all boils down on how the halogen cycle operate: At cold temperatures (when the lamp is off), nothing happens. At medium temperatures, like the bulb wall uses to operate, the halogens tend to attack the tungsten, this is tge way how the bulb gets cleared from the darkening.
At the temperatures the filament operates the tungsten-halogen molecules are breaking, releasing the tungsten there, so elevating the tungsten vapor pressure around the filament, so effectively "returning" the tungsten back onto the filament.


But in the lamp there is not just the hot tungsten, there are colder sections too, like the areas where it goes into the seals, supports or so. Normally these are designed to operate at temperatures where the tungsten get still released, but that uses to be designed for nominal supply operation.
he risk with the dimmed operation is just there, if these parts gets colder, below the threshold where the tungsten gets released, it then gets attacked by the halogens. And if operated there for long periods of time, the halogens may etch away these psrts rather quickly.
How much you have to dim a bulb to get some of its tungsten parts into that dangerous temperature range depends on its exact design. And even tiny invisible details make tye difference there. So each brand of essentially the same spec lamp may behave completely different.
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eyecandescent
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Re: Just a question « Reply #5 on: December 23, 2022, 09:33:22 PM » Author: eyecandescent
Well... that's interesting. I actually do enjoy very dim lighting at times, especially in chandeliers. Does low-dimming, orange/red light hurt traditional incandescent lighting, as well?

I will have to keep this all in mind. I guess if I don't dim below 60% or so.. the Halogens will be okay.
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Medved
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Re: Just a question « Reply #6 on: December 24, 2022, 01:27:53 AM » Author: Medved
How the halogens respond is really dependent on their exact construction, each brand and lamp type, even its generation (as the design is evolving over the years of production) could be way different.

Classic incandescents with inert atmosphere (vacuum, Ar, Ar/N, Kr, Xe,...) are 100% immune against low brightmess, on the contrary there you really get virtually infinite life in terms of filament evaporation.
It is only the galogens, where the gas fill is really chemically interacting with the tungsten (and maybe other metals) inside, what may cause problems if their design is unfortunate in this matter.
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James
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Re: Just a question « Reply #7 on: December 26, 2022, 07:22:49 AM » Author: James
There are two accelerated failure mechanisms of dimming halogen lamps.  The stop of the halogen cycle and blackening is rare.  But premature failure due to decreased temperature is very common, and more of a problem with lower current lamps which use thinner tungsten wire that makes then more susceptible.

Low voltage halogen lamps are quite resistant because they run at high current and have thick filaments.  High wattage lamps also.  The biggest problem is with mains voltage low power lamps less than about 150W.  Their filaments are so fine that they are quickly corroded away when dimmed.  Actual life might only be a couple of hundred hours, a small fraction of the rated duration.  If it is intended to dim such a lamp, it should only be attempted with a better quality lamp from one of the main manufacturers which have superior thermal management to limit such problems.  These might cost twice as much as cheap lamps, but in the dimmed state can be expected to last many times longer.
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