Metal Halide Arc bulbs for home? Crazy?

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wrote:

Thanks. That's also a possibility.
I already installed four 4' 2 bulb fixtures (total of 8 fluorescent bulbs) and the result leaves some room for improvement. It is just not bright enough.
I suppose I could install, say, 2 more 8 foot fixtures for the total of four 8 ft bulbs. There are some high efficiency ones, the last time I checked, HD was out of them.
i
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Try swapping for full-spectrum bulbs in the florescents, and/or moving them farther apart.
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They mostly have higher power bulbs already, but yes, I will see if I can replace the remaining cheap ones with full spectrum.
i
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I would avoid those, since they produce less light. Typically about 1/3 less.
If you are getting new fixtures, then I recommend 4-footers with electronic ballasts and taking F32T8 "lamps" (bulbs). And get bulbs of color code 830, 835, 841 or 850 (or GE ones SPX30, SPX35, SPX41, SPX50). The 8 or SPX means color rendering index in the low, maybe mid 80's as well as - unlike most other fluorescent lamps - their color distortions mostly in the direction of making colors brighter and more vivid. Also, these have full light output.
If you want daylight-like color close to that of noontime tropical sunlight, then get 850 or GE's SPX50. Just be sure to have enough fixtures to get things nice and bright - otherwise this icy cold pure white can cause a "dreary gray" effect.
The 2-digit part of the color code is an abbreviated nominal color temperature in Kelvin.
30 - "warm white" 35 - what I call "semi warm white" 41 - "cool white" (but with better color rendering than actual "cool white") 50 - icy cold pure white, sometimes looks very slightly bluish
As for the "7" and GE SP as opposed to 8 or SPX: The 7 and SP are a lower grade with a slightly different spectrum and color rendering index in the upper 70's, and their color distortions are not as flattering as those of "8" and "SPX". Home centers normally have the 7-color grade ones. I would go to an electric/lighting supply shop or an online seller for 8-color-grade ones.
If you already have fixtures taht take T12 40 watt bulbs, then get Philips Ultralume bulbs of the color temperature that you want. They are also "better triphosphor" with color rendering index in the low 80's and color distortions mostly in flattering directions.
- Don Klipstein ( snipped-for-privacy@misty.com)
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Eh...ditch the fluorescents and MH's and get *low* pressure sodium. Not the pinky yellow of most contemporary streetlights (high pressure sodium), LP sodium give that nice almost monochromatic yellow which you don't see much of anymore but used to be used for parking lots and some streets. IIRC more lumens per Watt than anything.
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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 ( snipped-for-privacy@misty.com)
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says...

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....
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snipped-for-privacy@phred.org is Joshua Putnam
<http://www.phred.org/~josh/
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"Cut the Blue wire, not the Red wire" . . .
"Oh, Crap".
D
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Don Klipstein wrote:

Of course.
But I do (did) like them in parking lots.
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I like them.
UV content is less than that in a similar amount of daylight. Just don't use them if the outer bulb gets broken - the bulb blocks nasty shortwave UV and UVB that the arc makes a little bit of.
Use in suitable fully enclosed fixtures rated for use with these bulbs, unless the bulb package says that the bulb is suitable for use in open fixtures. Every few blue moons somewhere a metal halide bulb that is not of the "protected" type (suitable for use in open fixtures) explodes.
- Don Klipstein ( snipped-for-privacy@misty.com)
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wrote:

Thanks. I am very interested in this. I am very tired of working under less that ideal lighting. Would you say that a 400W bulb provides "ample" light for a garage? (say 20 x17 feet, drywall) Or would you say that going higher may be warranted?
i
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Ignoramus4324

A single bulb (point source) is going to create a lot of shadows.
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Jim Yanik
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Would it still apply if the light was directed at the ceiling?
i
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wrote:

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.
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Jim Yanik
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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 ( snipped-for-privacy@misty.com)
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snipped-for-privacy@manx.misty.com (Don Klipstein) wrote:

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.
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snipped-for-privacy@newsguy.com says...

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.
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snipped-for-privacy@phred.org is Joshua Putnam
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John Hines wrote:

What's inside *after* it warms up?
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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 ( snipped-for-privacy@misty.com)
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Our local YMCA has high discharge lamps in the pool area. They are faced towards the ceiling whicj is metallic and reflects the light down.
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