Is it bad to run HID fixtures indoors without cooling? I notice when I run my MV or HPS fixtures in my room, I smell a hot smell after about 10 minutes, so I usually switched them off after that. But I know it's bad for the lamps. Since I know the lamps get very, very hot when in use, I thought of putting a small fan blowing into the slipfitter area. Would this help? It does smell hot on my NEMA and cobra head fixtures. If the lamps were exposed, like on a board setup it wouldn't get as hot I'd think.

I have run various "outdoor" HID lights indoors without any problems.Just position heat sensitive materials away from the light.

This seems like a silly question unless I'm missing something obvious. I'm Pretty sure they're designed to work over a WIDE temperature range, as they're deployed in the alaskan winters as well as the scorching tropics. They'll be fine at room temperature.

For tye fixtures it is for sure OK (unless they become somewhat covered, that would be a no-no).
But many are designed to run pretty hot and so smelly (the dust or paint components decomposing), too much to be caaeptable for indoors.
There is no generic cure. Sometimes a strategically placed fan may help, but it may also form quite a big stress points (some parts cooled way more than others, forming temperature gradients so stresses). But because outdoors use to be windy and even rainy, it shuld not become out of the design limits.

This seems like a silly question unless I'm missing something obvious. I'm Pretty sure they're designed to work over a WIDE temperature range, as they're deployed in the alaskan winters as well as the scorching tropics. They'll be fine at room temperature.

I don't think it's silly. Some of these fixtures actually state they aren't for indoor use, sometimes because they rely on the air currents outside to help cool.

For tye fixtures it is for sure OK (unless they become somewhat covered, that would be a no-no).
But many are designed to run pretty hot and so smelly (the dust or paint components decomposing), too much to be caaeptable for indoors.
There is no generic cure. Sometimes a strategically placed fan may help, but it may also form quite a big stress points (some parts cooled way more than others, forming temperature gradients so stresses). But because outdoors use to be windy and even rainy, it shuld not become out of the design limits.

See that's what I'm thinking on windy, etc, the fixtures I know I saw somewhere stated for outdoor use.

Like here the installation guide of the NEMA head states for outdoor use and not areas with limited ventilation. But maybe open areas indoors are fine as long as not covered:

GE 201SA Installation

Unless you're planning on running the light in a small closet , I don't see it being much of a problem . I've ran my finned M-1000 for over an hour in the house with no ill effects other than the room getting substantially warmer ! I'm gonna say that what your smelling is either dust or fingerprints burning off the lamp . That being said , if the fixture has a plastic lens/refractor I'd recommend running it positioned as it would normally be situated in "the wild" as not to expose the plastic components to heat in ways they normally weren't designed for .

 HID CAN be used indoors with no ill effects. Just look at warehouses , arenas , ETC . Our paint dept. at work was lit by HID for years with no issues ! The temp in there can reach over 130°F at ceiling height during the summer !(I know this cause I've been up there in the scissor-lift running new compressed air lines )   HOLY CRAP IT'S HOT UP THERE !!!

Yeah generally more HID core and coil ballasts are rated to pretty generous max surface temp ratings but if you're concerned about the ballast overheating you could run it for an hour and then measure the ballast temperature. If this is a fixed light and you're concerned about ballast temps, remote ballasting is a option you could look into too.

I don't think it's silly. Some of these fixtures actually state they aren't for indoor use, sometimes because they rely on the air currents outside to help cool.

Many materials tend to smell when hot and that could become problem indoors. Plus for indoor use, there are stricter requirements for UV and those fixtures may not meet that...
Plus outdoor tends to use louder ballasts, probably exceeding some standard for an indoor use too.

For the ventilation I doubt anyone sensible would rely on real wind to cool it down.