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My experience with fluorescent lights in my garage has been dismal.  They work fine above freezing, but are very slow to reach full illumination when below freezing, and never do more than glow feebly at temps of -30. Lowest temperature observed here on my porch is -47C

I've tried several types of LED screw in bulbs as my porch light.  Again:  They work only down to a certain temp, then get dim or don't start at all. Alas, here in Alberta, the working temperature range is only a subset of the environmental range.

I've inquired with various bulb makers, and while -18C (0F) is common enough -- likely used for freezers, so I've not found any that claim better than that.

Is there a light bulb type that works from -50 C to +40 C (-70F to 110F) other than the traditional tungsten?

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    Looking at some quality (not el-cheapo) outdoor FIXTURES (not LED made to pretend they are incandescent bulbs, most of which expect to be used indoors) I see minimum start temperatures of -40C specified. +40 is also in range. As a rule, LEDs love the cold, but the driver electronics are likely more limited by available parts – Ecnerwal Sep 10 at 3:30
  • As a light bulb type there are metal halide medium base lamps. These would require a properly sized ballast to function. The problem with metal halide is they can take 5+ minutes to warm up. It is possible a higher end led would be what you want, LED’s should work better in the cold. My big led flood lights have maybe 4 square inches of active diode but the heat sinks are over a square foot wide and several inches deep. For quality LED lamps look for it to be DLC listed and your country requirement “Ca”? – Ed Beal Sep 10 at 18:44
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    Is there a heated environment anywhere nearby (i.e. is your garage attached to your house)? One possible solution could be to mount LED emitters, which like the cold, in your garage, and place the driver circuitry which dislikes the cold somewhere warmer. – Nate S - Reinstate Monica Sep 10 at 20:57
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-50 degrees is unrealistic. Even mil-spec components won't work that cold. It sounds like you just tossed that out there, so I'll assume you mean something more practical.

Fluorescent revisited

Your experience with fluorescent lights has been disappointing because you're using J random cheapie fluorescent lights, with no regard to their cold performance.

What you need is a programmed start ballast. Those work a different way. You know fluorescent tubes have preheat filaments (not unlike an incandescent filament) in the ends. Those can "warm up" the tube so it takes a much lower strike voltage. That also means less spallation on startup (the thing that leads to black rings on the tubes), which greatly increase tube life. The colder the bulb is, the higher a voltage it needs to strike.

  • Instant-start ballasts, the stock-in-trade of cheapie fixtures, don't even bother using the preheats. They just apply a very high strike voltage. But even that is not high enough to strike an ice cold tube.

  • Rapid-start ballasts use the preheats, but after ~0.8 second they just slam on a high strike voltage to "force" it to start.

  • Programmed-start ballasts run the preheats for as long as it takes, which isn't real long with 700C filaments warming the gases in the tube! Meanwhile they apply a very low strike voltage (only enough to strike a warmed tube) which is easy on the tube.

Programmed-start ballasts are readily available for $20-ish. Since they use the filaments, they need 2-wire non-shorting tombstones, so if you currently have instant-start ballasts, you'll need to change the tombstones.

LED, if it's well-built

A competently built LED will also work just fine in the very cold, assuming the driver and LED can handle the temperature. It will come on instantly and reach full brightness quickly as the chip itself warms up. Actually, it will run slightly more efficiently in the cold.

If you really must operate at -50, preheat the fixture

Add some resistive heaters on thermostats, so they preheat the fluorescent ballast, LED driver and LEDs proper. They should shut off once the device they're heating reaches 32F. You don't need to preheat the fluorescent tubes; the programmed-start sequence will do that.

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    Actually @Harper the "full mil temp range" for equipment and components is -55C to +125C. And yes there are components made to operate over that range. I have in the past been involved in the design of various sorts of mil spec gear that would meet that temp range. One piece of gear had an LCD display module that incorporated a resistive wire heater that engaged below -10C to permit even the LCD to be operable when the system temperature was colder than that. – Michael Karas Sep 10 at 6:04
  • But cold temps do cause problems with program start or not. Preheat helps but at extreme temps fluorescent’s just don’t produce enough heat to maintain a strong plasma. – Ed Beal Sep 10 at 9:54
  • @EdBeal they guarantee -18C/0F with tubes fully exposed. Too much below that, agreed, the environment may steal heat from the tubes faster than they can make it... In that case go for an enclosed fixture i.e. Weathertight, intrinsically safe, or a troffer, to help contain the heat. – Harper - Reinstate Monica Sep 10 at 16:53
  • The OP is referencing-30c as a temp observed and -50c as a desired range so fluorescents are out no matter what type. I know I have had metal Halides strike and run at -25f but they took a while longer than normal to get bright, when I worked in colder temps I was on day shift and do not remember the metal halides having any problems but sodium vapor we lost a lot of starters the lamps were not able to produce enough heat to fully illuminate. – Ed Beal Sep 10 at 18:16
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    @EdBeal well, that's an answer! High Intensity Discharge lights would work, I forgot all about them. The "ballasts" are entirely magnetic, the most electronic thing in them is a capacitor, (or on HPS, a VBO device whose job is to shut off the 4000 volt ignitor once the lamp strikes, but only HPS have those). As for starting slower, who would notice? On fluorescents, I'm saying if you can insulate the tubes enough for the preheats to reach operating temperature eventually, the programmed-start ballast will strike at that point. The only question is if the ballast needs preheating. – Harper - Reinstate Monica Sep 10 at 19:03
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As Harper and I have discussed a metal halide lamp may be what you want. I would choose a dry cap (not oil filled) in the extreme cold. Places like 1000bulbs has inexpensive lamps and ballast kits. Your ballast needs to be matched for the lamp wattage and have the correct input voltage. On the bigger 400w & 1000w lamps these ballast usually have 3 or 4 different voltages. A 50w metal halide lamp was the smallest I could find with a quick search this will produce 3400 lumens (2x the lumens of a 100w incandescent) with a 10000 hour life span about 5-10 x the life of an incandescent depending on brand.

The only thing is these take a minute to “glow” and 5 minutes or so for full brightness. Lamp cost ~12$ through 1000 bulbs I don’t have time to find the ballast but will tonight if you go this route.

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