Metal Halide Arc bulbs for home? Crazy?

[Jim Yanik]

Ignoramus20878 wrote in news:rA%if.785$ [e-mail]:

A single bulb (point source) is going to create a lot of shadows.

[John Hines]

The point I'm trying to make is that heat is a problem that needs to be addressed, and that it will be a problem if you try and build fixtures in, and not leave them out in the free air.

A small muffin fan is an easy DIY to do cooling, when one doesn't have ability to design and test a better enclosure.

[John Hines]

MH bulbs give off a lot more UV when the are warming up, I've seen warnings not to look directly at the bulb when it is warming up.

Given that until it lights up, there isn't anything but an arc inside, this seems quite wise advice.

[Ignoramus20878]

Would it still apply if the light was directed at the ceiling?

i

[Ignoramus20878]

I have a dozen of 110v muffin fans, all highest quality stuff from military equipment. Here's how I used one of them:

Using one sounds like a good idea!

What do you guys think about this fixture:

Thanks!

i

[Joshua Putnam]

I no longer have that living room, the MH lights I have now are garage shop lights.

The living room was about 12x24, light intensity wasn't up to summer daylight but was brighter than mid-winter daylight. (The room occasionally doubled as a small photo studio, B&W only so I didn't have to worry about color temperature.)

[Joshua Putnam]

Considering how bright they are when they are warmed up, I'd consider it a good idea for indoor installations to have the bulb where it can't be seen at all -- facing up to bounce off the ceiling, or else you have a real glare problem.

[Ignoramus20878]

This is excellent. What kind of setup did you use, did you direct light upwards? I will gladly spend $200 *if* it gets me a very brightly lit garage.

i

[John Hines]

Watch out for dust build up.

This is where I shop

got one of the "vertizontal" reflectors. which is 4' in dia, with a

250w MH bulb.

[Jim Yanik]

Ignoramus20878 wrote in news:ZO0jf.569$ [e-mail]:

Sure,you will still get shadows though. The worst part will be when your body blocks some of the light,usually where you need light the most.

[Steve Kraus]

What's inside *after* it warms up?

[Don Klipstein]

Is this sarcasm?

Low pressure sodium does indeed achieve more lumens per watt than anything else, but I would not use it even to illuminate a parking lot.

The monochromatic orange-yellow light turns everything into an orange-yellow version of black-and-white!

Reds become dark gray or black, except for a few fluorescent reds. Oranges become gray. Yellows and whites look identical. Greens become shades of gray. Blues become shades of gray, sometimes black. Purples become shades of dark gray. (Technically brighter or darker shades of orange-yellow, but when you are only seeing orange-yellow different shades start to look like shades of gray.)

Most colored objects appear darker under low pressure sodium than under other light. Because of this, I would not consider a lumen of low pressure sodium light to have as much "illuminating power" as a lumen of another kind of light.

I thought the lowest possible color rendering index was zero until I heard that low pressure sodium rates a -44.

- Don Klipstein ( [e-mail])

[Don Klipstein]

Now, I gotta remember how many square feet is usually illuminated by a quad 4-footer in typical office space... Maybe 96 square feet, maybe even less.

I do remember calculating that typical lighting levels from overhead lighting in office space was generally in the range of 110 to 200 footcandles (lumens per square foot). A quad 4-foot fluorescent fixture typically produces around 11,000 lumens (13,000 lumens for no light losses with brand=new 40 watt bulbs). One of these per 96 square feet would achieve about 115 footcandles... Maybe common is a quad 4-foot fixture per 64 square feet, which would achieve about 170 footcandles.

(Going by lumens per square foot, not actual photometric readings.)

A 400 watt metal halide produces about 40,000 lumens - figure more like

35,000 once the bulb has aged somewhat. 20 by 17 feet is 340 square feet. Assuming good reflection of light hitting walls and even light distribution, the illumination level would be on the low end for office lighting.

What I would be afraid of is that the light would not be distributed well and would hit many work surfaces at a bad angle. Unless temperatures are unfavorable for fluorescent, you are probably better with an adequate number of fluorescents - 12 to 20 4-footers to achieve an illumination level like that in an office. If you use 400 watt metal halide, 1 may not do well, you may need two.

- Don Klipstein ( [e-mail])

[Don Klipstein]

MH bulbs have UV output maximized when they are most of the way warmed up, just as they are beginning to shift from mercury color to metal halide color. UV content is roughly equal to that in an amount of window-filtered sunlight equal to the fully-warmed-up output of the metal halide.

- Don Klipstein ( [e-mail])

[Joshua Putnam]

....

I don't know the CRI, but I have to agree, it's the worst light I can imagine for a home or shop. I had a college classroom that was lit with LP sodium, a horrible idea that was no doubt some sort of energy conservation experiment. Though, since it was a psych classroom, we all wondered what the experiment really was....

[spamTHISbrp]

"Cut the Blue wire, not the Red wire" . . .

"Oh, Crap".

D

[Steve Kraus]

Of course.

But I do (did) like them in parking lots.