Any observations as to good & bad results from fluorescent lamps in cold temperatures? I tested various fluorescents at home at a temperature of 32F/0C (freezing) to see what kind of performance I would get. I have heard stories of lamps not starting or failing to get to full light output and I have observed dim flickering lamps outside in the cold, so I tested my own.

I found the linear fluorescents with magnetic ballasts - instant start, rapid start or preheat, all turned on normally but were dim, flickered/pulsated for a minute or two and were at full brightness within 5 minutes (none of these were enclosed). With electronic ballasts, the same behavior was noted only with no flicker or striations.

With compact fluorescents it was more interesting. My magnetic preheat capsule and magnetic circline flickered for a few seconds after starting normally and the color was fairly normal throughout warmup. However, the PL-C lamp & adapter was the brightest at startup and didn't take long to warm up completely, with no flicker at all. The Ikea electronic 20w lamp (Megaman) worked exactly the same as in warmer temperatures. A Commerical Electric 19w spiral had striations a few seconds after start that reversed direction a few seconds later. A Maxlite 23w spiral was almost entirely pink for a minute after start. The GE 45w spiral took a good 4 or 5 minutes for the whole spiral to become an even brightness, starting from the tube ends. All my Lights of America CFLs worked fine, just a bit dim at startup but normal color. A GE 20w electronic "bullet" CFL worked fairly normally, but the 9w globe started extremely dim (as it does even in warmer temperatures) but would not warm up much past halfway until I took it out of the cold!

So, it would seem that fluorescents generally are OK in freezing temperatures but maybe someone knows how they do in extreme sub-freezing temperatures (it never gets that cold here).

My F96T12 fixture NEVER warms up in the cold while as the F34 ALTO's have a very hard time starting same thing with the F40's but those are Feit's
CFL's here especially Sylvania's start out very pink as they are amalgam lamps and it takes a few minutes for the mercury vapor to fill the tube sometimes they show striations but the F34's always show striations and never warm up in the cold here I left one on for a day and it warmed up fine

For me it never gets cold enough for this to be a worry. Today min 20C, max 32C, and no aircon operates on the roof where I was, just great heating, from sunlight as well as aircon outlets. Display fridges here use internal lights, may affect them when replaced, but most never are turned off anyhow.

My parents garage has a F96T12 fixture with Philips ALTO lamps in it and when it gets cold out there the lamps never fully warm up.  You can leave them on for hours and still see striations and sometimes a bit of flicker.

A gas station I filled up at on a cold day was lit by F96T12/HO Econo Watt lamps and they were all showing striations and flickering a bit, even after being on many hours.

It seems fluorescent lamps with krypton in them (energy saving lamps) have problems in cool to cold temperatures...

Also I have noticed that the cathodes are always heated on the busses that i'm on probably to help them fire when it is cold as RS lamps have a hard time firing up when it is cold

Reduced wattage lamps are recomended for 60 deg. ambeint temp min. To install reduced wattage lamps where it will get below 60 deg. is not recomended as it will degrade the lamps performance.

Like the F96T12/HO Econo-Watts I saw outside at a gas station on a 50deg day.  They all showed striations and were dim.

I have been into a local electrical dist, and asked for the 110w cold weather cool whites. They brought me econ-o-watts and told me all HO lamps are cold temp lamps thats what the HO means. With salesmen like that its no wonder that lamps are misused I had him get me a ballast and showed him that these lamps were only good for 60 deg. He said he had no idea and thanked me for telling him.

Powergroove your local Home Depot or Lowes carry the 110 watt low temp fluorescent F96T12/HO lamps. I don't know how well they will handle higher temperatures as I have yet to find out if they differ from other HO lamps in construction. Anyone know?

BTW the VHO and VHO-O lamps are specially designed for specific temperatures. The VHO lamps have long stems to ensure proper mercury pressure during operation in temperatures that are not too cold. For low temperature operation the VHO-O lamps use shorter stems which allow them to do well in such applications.

I've been using Cold Temp Sylvania 110 watt H.O's at work for years. They really don't seem any different than regular H.O.'s. I have heard that they needed to be labeled as such since normal wattages for Cool White were outlawed; therefore, these lamps needed to be special designation.

They supposedly won a cold weather exemption. The F40CWs were the most popular lamp in the land. The government claims they are inefficient, I say just too popular for them. I think the sensible thing to do is label Energy Saving lamps for indoor use only.

My CFL lantern is always nearly at full power. But I have a very cheap Energy Saving lamp and this lamp never warms up in the cold.

I just tried a new setup using a 2-lamp electronic ballast shop light fixture that is rated to work with 32w T8, 25w, 34w, and 40w T12 lamps. I'm using 34w Sylvania ecologic energy saving lamps (Krypton filled) on this instant-start ballast. I put the tubes in the clear tube-guards that have the black rubber end caps to retain heat (they make the lamps look neat, kind of like old Westinghouse T17's with the black caps). I figure this combination should give the best results in cold temperatures IF you had to use the econo-watt type lamps (which I normally don't).

At 50 degrees Fahrenheit, the lamps start instantly but within a few seconds start showing striations, which are interesting in that they move in various directions & speeds and sometimes stop all together (but are still there) - typically getting faster and less visible as the tubes warm up. There is no flicker, so working under the light is just fine - you don't even notice the striations unless you look at the tubes themselves. It takes about 15 minutes for the striations to completely disappear at that temperature.
Even after many hours, the fixture ballast and tubes -even right over the electrodes - are very cool to the touch. Must be a very very light loading on these lamps or something about the krypton that keeps them from heating up.

My parents garage has a F96T12 fixture with Philips ALTO lamps in it and when it gets cold out there the lamps never fully warm up.  You can leave them on for hours and still see striations and sometimes a bit of flicker.

A gas station I filled up at on a cold day was lit by F96T12/HO Econo Watt lamps and they were all showing striations and flickering a bit, even after being on many hours.

It seems fluorescent lamps with krypton in them (energy saving lamps) have problems in cool to cold temperatures...

The same happens to me! I is sooooo annoying...

The F96T12 60w lamps are truly awful in the cold. Just the air from an air conditioning duct or a room temperature of under 70 will cause endless striations and dim operation.

I revisited the 34w-in-the-cold-garage test - now using a LOA electronically-ballasted shoplight with GE Watt-Misers (non-Ecolux). That made enough difference....they might striate a little in the cold for a few minutes, but most of the time they work fine and seem just as bright as my 40w T12's (of course the 34's are brand new). The electronic ballast definitely helps, as does having lamps that are NOT low-mercury.