Metal Halide Arc bulbs for home? Crazy?

[m Ransley]

Uv filters are nearly clear to the eye and might lower output less than

1%, but are probably part of the bulbs glass.

If you have 8, 4 ft 40 watt flourescent now and are not happy then you might be fine, if you upshoot the light, you will likely only triple output. Flourescent are not more efficient as someone stated. But go by lumen output, figure out what your tubes are and you decide if you can handle it. There is a temp -time rating for startup so look into that as well.

[John Hines]

They need a ballast (big transformer), and a capacitor. They take thousands of volts to ignite, and thus require special HV socket and wiring from ballast to socket. The ballast will require cooling (fan of) it's own.

A fixture designed for indoor use should have a UV filter option, this is generally a piece of heat tempered glass.

They will generate more UV than standard lights, so more fabric fading is common.

It would be far easier to do it with 250 watt/U bulbs, since they are more common, and work in any position.

For indirect lighting, you can get an outdoor fixture from a box store, in the smaller sizes, that should work. At least enough to try it out.

[Goedjn]

Try swapping for full-spectrum bulbs in the florescents, and/or moving them farther apart.

[Jim Yanik]

"Jim McLaughlin" wrote in news:34CdncmBVouQ3RbenZ2dnUVZ [e-mail]:

Those metal halides emit a LOT of UV,and are not filtered. They will fade any colored items,and are bad for your eyesight if not filtered.They also can explode and shower you with broken glass shards.

[Jim Yanik]

[e-mail] (Chris Lewis) wrote in news: [e-mail]:

One other note;I worked in a lab with MH lighting,and any brief power interruption meant we went without light for the time it takes for them to cool and then re-ignite,about 15 minutes,IIRC. A PITA. Our lights had UV filters,and reflected off the white ceiling. I would not want them in my home.

[Jim Yanik]

"Joseph Meehan" wrote in news:1CJif.125571$ [e-mail]:

They would do the same under Clinton's or Kerry's America.

Yeah,just think "Janet Reno",about breaking down doors with guns drawn.

[MC]

They need to have matched ballasts, Only use in the specifc fixture designed for the reated MH Bulb.

[CJT]

There wasn't/wouldn't be a "Patriot Act" under them.

That guy wasn't a "law abiding citizen."

[Ignoramus4324]

They mostly have higher power bulbs already, but yes, I will see if I can replace the remaining cheap ones with full spectrum.

i

[Don Klipstein]

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 ( [e-mail])

[Don Klipstein]

I believe the degree of eye damage was overblown. If the bulb has just a crack, not much nasty UV gets out. And the way I hear it, eye irritation from shortwave UV and UVB is generally recoverable.

But if the bulbs are in an enclosed fixture, then the fixture covering stops any nast UV that gets out of the bulb.

- Don Klipstein ( [e-mail])

[Don Klipstein]

That last one is not true. Especially good fluorescents have only about the same efficiency as 400 watt metal halides.

- Don Klipstein ( [e-mail])

[Don Klipstein]

Any old glass, polycarbonate and the common acrylic sheets are plenty good for protection from shortwave UV and UVB from a broken bulb. The UVA that gets through these materials will be less than that in a similar quantity of daylight. Metal halide lamps designed for illumination are actually not that efficient at producing UV - they are somewhat good at specializing in producing visible light.

The special materials mentioned by Michael Daly are only needed when you need a degree of UV removal much more severe than merely having a fair amount less UV than is present in a similar quantity of sunlight that has gone through window glass.

- Don Klipstein ( [e-mail])

[Don Klipstein]

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 ( [e-mail])

[Joshua Putnam]

My 400W MH fixtures don't have fans for cooling, just the back of the ballast exposed to air. A lot of warehouse and parking-lot lights use 400W MH without cooling fans.

A good fixture will include tempered glass that absorbs UV, I never had a problem with fading with my MH living room light, and my photographic light meter indicated less UV than daylight of the same intensity. (That's still more UV than you'd get from a fluorescent, but not a dangerous level.)

[Don Klipstein]

About that part about the especially high voltage:

MH fixtures include the ballast, socket and wiring in between - problem solved. Also, the high voltage starting is for the "pulse start" types, which most 175 and 400 watt MH are not.

Pulse start has an advantage - it allows an arc tube lacking a starting probe, and a "simpler cleaner" arc tube makes those are slightly more efficient and have slightly better lumen maintenance - maybe a little significantly better. Ones with ceramic arc tubes have better color rendering and those are pulse start - but I believe are mainly lower wattages.

- Don Klipstein ( [e-mail])

[Steve Kraus]

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.

[Amun]

But you will be the envy of all your neighbors. With a nice tan year round

[Ignoramus20878]

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

[Ignoramus20878]

Thanks, that's very interesting.

In your living room, which I hope is comparable with my 20x17 ft garage, just how bright does it become with a 400 W MH light? Are you somewhat satisfied, fully satisfied, is it bright like a day, etc?

thanks

i