Any of you guys could tell me if really cold weather affects the lumen output of LPS? I came home tonight and my fixture seemed dimmer than it normally does, We are having a unusal cold snap, Temps are in the upper 20's with high winds making wind chills in the teens, The LPS fixture as you probably already know is a open bottom NEMA head. I know LPS relys on its own heat to vaporize it sodium but thought it would need extremley cold conditions to affect it. It's 18watt sox-e.

Cold weather shouldn't really affect LPS lamps too much,usually most fixtures are enclosed warming the area around the lamp.But in your open NEMA, with cold temperatures and a windchill, the small 18W sox maybe suffering from more heat loss than larger lamps would causing some reduced light output.

prehaps you can find a Dewar Jacket to fit over the lamp.

In my opinion, the warming up could be slower due to the colder sodium that will take longer time to warm up and evaporate.

This was quite a noticeable lumen drop, Looked like it was running at about 65% Full lumen output, And when I came home it had been running for almost 5 hours. I seen open bottom NEMAS before but there 35watts. The fixture was out in the wind and the winds were about 20-25MPH Gust. Very cold last night for florida. I never of thought cold weather like that would affect performance.

Wow, it sounds like your winter weather is worse down in Florida compared to what we have had here so far on the West Coast of Canada.Today was a mild 54F.I tried my 35W LPS lamp on a F32T8 electronic fluorescent ballast,the light output is about 80% compared to the original 35W LPS ballast.

Oh yeah. The freezing temps have only been at night. We only warmed up to 48 fairenheit today. The wind droped off tonight but stil the fixture is much dimmer than normal. PS, You should see how our news stations freak out when it hits the freezing mark! It's top news! Wear protective cloths Cover plants, ECT. Top news tonight was about the orange groves and how they had to run sprinklers to encase the orange trees in ice to insulate them! LOL! I am from Pennsylvania Originally and find it hilarious. 2nd story, How power companys are doing with the increased demand for electric, 3rd story how houses burned down due to rigged heaters!

LOL here we have around O°F now! In eastern Canada the winter is cold, very cold. I have to try a LPS in as cold temperatures.

I just moved from Alaska to Louisiana, right in time for snow!  Next time I'm back home when it's cold (like -20 cold) I'll have to try out my LPS fixture.  I know at those temps, Caster, Philips and Regent MV lamps won't start, and compact fluorescent lamps burn themselves out trying to start.  Incandescent/halogen and HPS seem to be the safest bets in the cold weather, although my older GE and Sylvania MV lamps start like champs too.  Haven't messed with MH enough to know.