OT metal halide garage lights

John Davies did pass the time by typing:

Seen them. Not bad, but I opted for your basic fluorescent lamps. They are easier to install, you can put in several banks, and the bulbs are cheap.

Used three 8' long (4X4' bulb) lamps for a four car garage. More than enough light even for paining and about 50$ total. Still need a trouble light under the jeep. :)

DougW did pass the time by typing:

... erm ...

painTing

I ran out of T. :(

You can buy Ts in bulk and get a better rate. Don't get the ones from China, the powdercoating wears off quickly. I get my Ts from Tom Tuttle in Tacoma.

Ta ta!

DougW wrote:

As the URL points out, you get a _lot_ more light from a 175 watt metal halide lamp than you get from an equal wattage incandescent lamp. In an ideal world you should audition a unit, though, to be sure that the color rendition is acceptable for what you plan to be doing -- think of those amber-ish sodium-vapor lights (which you really don't want to use) commonly used for street lights and what non-color a green car looks like under them. Keep in mind too that metal halide lamps make light with an enclosed electric arc and so run significantly hotter than an equal-wattage incandescent would, so you want to be sure there's room for some air circulation around them, tucking the head up between two rafters probably isn't a good idea.

Lastly, there's warm-up time. Enclosed arcs take time (several minutes at least) to come up to temperature before you get full light output and full color and every start cycle takes life off the bulb, so it isn't a system to use if you want instant-on and frequent, short cycles. If that's a problem, you could install parallel systems, metal halide for extended shop time and incandescent for finding a screwdriver to fix something in the house, but that's an increased cost, too.

Someone else in the thread mentioned fluorescents. They're cheap to run, give good light output for the wattage and run cool, but those who live in places where it gets cold would do well to spring the extra bucks for "cold-start" ballasts. The $6 Wall*Mart "shop lights" have a ballast made out of a choke, a resistor and some chewing gum and once the temperature gets down to freezing the lights just sputter, hum and glow. Color rendition can be an issue with flos, too. Cheap tubes have a wicked green spike in their output and holes in some of the rest of the spectrum. If color matching is going to be important, spring for the more expensive "full spectrum" tubes.

Lastly there's shadows. Lamps that have a single point source cast hard shadows (the smaller the source, the harder and bigger the shadow), so you want enough incandescents or metal halides spread around so you get at least two sources at every work station. Flos are a long narrow source, so at any given point along the tube your shadow is filled from the light to your left and to your right. You still get shadows, but they are softer. You still want multiple, spaced sources, though.

Good luck.

A few things to add:

"Cold Start" ballasts simply mean that they will start when it gets cold. You still have a significantly lower light output when the temperature gets below about 50 or so.

For "low bay" installation like a typical garage, with point source lamps with diffusers to even out the light somewhat. The tradeoff is that diffusers also spread light upwards, so you want a light ceiling to minimize loss.

Besides the warm up time, metal halide lamps have what's called a restrike time, which is the time it takes for them to restart after you've shut them off. This is typically 5 minutes or longer.

All arc lamps flash on and off rapidly. There are two problems with this:

1. Some peoples eyes become fatigued rapidly by this
2. In a shop, this can lead to an issue called a "strobe effect", where rotary saws and such can appear to be stationary while they're actually moving. Metal halide and sodium lamps are most affected, color corrected mercury and flourescent (because they have phosphors) are the least. Even a small amount of suplemental incadescent or natural light will solve these issues.

You get what you pay for with flourescent fixtures. The "professional" grade have a higher light output than those $10 Home Depot shop lights.

i cant comment much abotu room lighting, but i have metal halide lights on my reef setup and theyre entirely too "sourcy" for a room... long flourescents cast a nice diffuse light, whereas the halides allow mid-noon type shadows.. very bright and good for stand mount spot lights, but as general room lighting, i would think of something else first.

-Steve 98 TJ