Lighting question for those with Metal Halide

Ok, I stumbled onto some lighting on Ebay that is priced right and exactly what I had been looking at for some time.



It is like the two on the left in the pic. These are Acrylic reflectors that provide some uplighting to eliminate the "cave effect" and are 400 watt MH, 120V (only, not multi-tap) and draw 4 amps. I have seen these lights in several stores and in fact the seller told me these came out of a Sam's Club. My local Wally World had them until recently and switched to T8 flourescents.

These are "local" to me, about an hours drive, so no shipping, and I can get them, complete with bulbs for $40 each, which seems to be a bargain for a complete used MH fixture. From what I can tell, they are about 7 years old and are advertised as working when taken down.

My question is how many I might need. I have stood in stores and pondered this, but it is difficult to imagine what it would look like in my "shop", especially not knowing the wattage of the ones in the stores. As I have previously mentioned, my Shop, *** aircraft hangar, vehicle maintenance and storage garage, pesudo attic/basement, is a 60x60 metal building, 16 ft high eaves, 12/2 roof (21 ft at the peak) and it basically white inside as it has that white plastic backed insulation that is applied before the metal was screwed on the outside, and has exposed "red iron" and red oxide primed purlins. The lights will be mounted at about 14 ft, possibly a little higher nearer the middle of the building. It has 14 ft doors and doesn't make sense to allow anything to hang below 14 ft.

I've looked at the photometrics and attempted to use the Lithonia lighting software, Visual, but it was beyond me to figure it out.

From the photometrics, I'm thinking of doing three rows of four lights (a total of 12) this would put each light covering a 15ftx20 ft area, in theory. This is 48 amps, which will be spread out electrically as I plan to use three wire circuits powered by double pole ganged handle circuit breakers (two opposite phase hots which are actually 240v and a neutral), and use double pole heavy duty 30 amp Pass & Seymour switches (which I already have, bought them on a super clearance). Using three switches, this will allow me to put two fixtures across the A buss to the neutral and two across the B buss to the neutral, for each fixture. Sharing the neutral like this is legal, legimate and doesn't overload the neutral. Code does require the ganged double pole breaker however. Essentially the neutral won't carry any current as I am putting two 120v devices in series across 240V. You do this every day in your house and don't even realize it. (with even distributed loads on both sides of the panel, the neutral from the meter to your panel carries little or no current.

Anyhow, enough of the electrical lesson, what do those few of you who have shops with MH fixtures think of my proposed coverage, too much?, too little? I expect to still need a trouble light ocassionally for under hood work.

To me, it almost sounds like too much, at 5700+ watts the meter should spin right fast. The other possibility is to go with 9 light fixtures, each covering a 20x20 square in theory.

I also have four 250 watt MH low bay fixtures with metal reflectors and low bay light diffusers on the bottom I can employ, possibly over the corner where the workbenches and drill press/lathe/hydraulic press/parts washer reside.

I expect to go tomorrow and buy them, I'm off work and don't want to miss out.

Charles

I have a couple of those type fixtures in my shop at work. The one directly over my table I had to unplug. It has the 400 watt bulb in it. The other is toward the end of the shop that is the entrance. I leave it on. I don't have a bench there. There was too much glare for my taste. The floor is gray paint with white walls. And when the lights go out it is about 15 mins. before the come back on.

On a safety note. If you happen to break one it will be VERY HOT as it goes through your skin! The electrical contractor I use when I need help will not install fixtures without covers lower than 20 ft from floor level.

Scott

Charles,
You have the model name/number of the lights? I might be able to draw up something on Visual to help give you an idea on the output @ work height, which is what you need to find out.

Pick up a Grainger catalog or their specialty lighting catalog. It may also be online at the website, not sure. It has some very basic layout guidlines for coverages I think it will answer your questions. My plant has MH's from
1000W down to 175's. 400's seem awfully big for a 12 to 14 foot ceiling, we have 250's at this height and they work fine when spaced correctly. I think lower wattage would work better at this height when laid out correctly because you will get a more even pattern. Yes the MH's burn very hot and should have covers at lower heights. The fixtures do take some time to relight if power should go out once they have been burning awhile. You can get these lights with a re-stryke so that it has a small light that comes back on instantly. We use these but the simple fix is to put a flourescent or an incandescant lamp on a seperate circuit, we keep one burning in various parts of the plant for watchman lights. On the other hand 40 bucks is dirt cheap, new bulbs are between 27 and 35 dollars, depends on the deal they got on them, at the supply house I deal with. Ballast kits run about 100 bucks for 1000's not sure of the smaller watt units, been awhile since I had to buy one.
Hope this helps.

Its a TX 400M PA22C, Link below has the links to the photometric data for this and several other variations of it.

http://www.lithonia.com/products/Fa...I.D.%20LightingLow%20BayAcrylume%AE%20Acrylic

The building has other lighting, for the past 7 years I have endured with two 500 watt quartz floodlamps, the type you see for $15 or so. They are mounted up on the 12 ft high purlin on one end of the building. They provide a surprising amount of area light. I will not be using the lights in the daytime. The building has 53 ft wide by 14 ft high doors with translucent fiberglass on the east end and 12 ft wide by 10 ft high of glass in a 14 ft high garage door on the west end, plus windows in the two man doors and skylights in the south wall. Daytime lighting is not a problem.

After experimenting with the 250w MH lights I have, I became concerned that that was not enough wattage. The lights I am looking to buy have the lower protective lens. MH bulbs are dangerous, even if the outer glass breaks the bulb will continue to work, but you can get a bad "sumburn" from it. I saw in the news recently that several people had been burned in a school cafeteria when a MH lamp was operated after the outer glass had broken off.

Charles

This is what I came up with using 12 of the TX 400M PA22C lights with the lens mounted at 14 foot high. Granted the ceiling is not quite right (I, too, am having problems with the drawing tonight - this ceiling is flat), but it should give you a general idea. I tried the same layout with the center row mounted at 19 feet high and the fc at the middle was low (10-20). IES says you should be around 50-60fc at workheight (set to 30in here) for detailed garage type activities. Reflection is set to light industrial. Your output will be a little lower than this due to the differences in the drawing and reflectivity of the ceiling, etc..



I think it should give you the output you require as long as you mount the lights as low as you can. The higher you mount them, the less light you will have down below.

I have 9 -175 watt fixtures mounted at 12 foot high. 1575 watts for a 30x30, 1/4 the size of your place.

Whatever you do, make sure you get several more fixtures. You never know when you're going to need to swap a ballast or bulb. One of my ballasts was bad from the get go, so I just swapped out the whole light for another one I bought.

Thanks for the help, I was using the WAG method and still not sure of what I was doing. The bottom of the lights will have to be kept at 14 ft since the building has the potential of having a 14 ft (or nearly so) tall tail of an aircraft in it (14 ft door opening). I did think I would buy at least one, if not two spares.

At least it would appear that these lights were operated in an airconditioned enviroment, which probably contributed to their long life. If money were not object I would be buying the I-beam by Lithonia with the T5 lamps, same light, less current consumption.

Charles

No problem. Let us know what happens. If you can pick and choose, make sure you get lights with lenses. I noticed in the ad it mentioned some lights did not have lenses. I believe the title also mentioned multi-tap? I dunno.

Good luck. You're going to love the new lights.

Well. I went and picked up the lights. $520 for 13 fixtures, no tax and the lady gave me 19 lamps to insure I have good ones. All in all, seeing the prices of used lighting, I think I got a good deal, free would have been best but this is as good as I have come across. I've been testing them one at a time today. Let them come up to full bright and then unplug the ballast (have it hanging under a ladder without the reflector) So far no bad ones. Once done testing the lamps, I'll start testing the ballast, one at a time.

Apparently only a few of the lamps had bottom lens covers and they were all gone. About half of the ballast were made in Ill in Jan '01, the remainder were made in Mexico in Nov '01. Identical units including p/n's .

The big part is yet to come, running conduit and pulling wires. The guy who erected the building offered to loan me an electric manlift, he is about retired now and only rarely needs it, so I can keep it awhile.

The bulbs I got are 360watt. They are the energy saver bulbs designed for a 400 watt rated ballast. She had some true 400w but I decided to stick with all 360's. Measuring the amp draw it appears that the one I am using for bulb tests is drawing about 3.4 amps, shaving over 800 watts off my original estimate of current use.

I'll report more later when I make some progress.

Thanks for the work on the visual program too.

They had some small reflector (about 15 inch) 250w units with long downrods with ball swivels that mount on 4 in boxes, but I wasn't about to attempt to rethink everything and doubted their ability to do what I wanted.

Charles

Funny, I tested mine the same way. Found out I had a bad one when I was relaxing in the house and smelled something really BAD. Went in the garage a found a decent amount of smoke and that horrible burnt electrical smell. Wife freaked and thought the kids would die from the fumes, so she took off for a while. Fumes were nasty, but I stuck around.

Anyway...

Let us know how it goes.

I wonder if you can get replacement bottom covers. I tried to get some for mine as some of mine are cracked, but I couldn't find them anywhere.

Good you stuck with the 400's. The 250's definitely would not have lit things up enough.

Ever have a long post nearly finished and have things crash?????????? ugh!!!!!

Anyhow, I finished testing all of the bulbs and ballast the other day, everything worked OK. I did find that the ballast made in Illinois draw about 3.4 to 3.5 amps and the identical ballast made in Mexico draw 3.8 to 4.0 amps and cause the same light bulb to produce some more light.

Today I decided to experiment with a light to see what kind of light pattern and brightness I would get. I have a warehouse step stand that is 10 ft at the top step. I can just barely reach the second purlin in from the side wall of the building, so I clamped a C-clamp to the bottom flange of the Z purlin and fitted a ballast with a wire pigtail (I save old cords I cut from appliances and such that I discard). I hung the ballast on the C-clamp and fitted the reflector (difficult considering it is 22 inches in diameter and nearly as high, installed a light bulb and fired it up. I let it run for several hours and after dark I turned out all other lights and observed the pattern. I did feel the ballast for heat, and while it was quite warm to touch, it was not hot enought to burn me. I could have used one of those IR temp measuring devices, gotta look into that, could find all kinds of uses for it.

I was hoping I might discover that I could get away with fewer lights, possibly 9 (less electricty used) but that is not going to happen. What I found is that the light, with the bottom of the reflector mounted at about 14 ft 4 in., just about where it will be when permanently installed, gives good lighting for about 7 to 8 ft from the center, a circle of about 15 ft. I should get good overlap with four lights in a row (15 ft center to center), and may have some shadowy areas between the rows of four (20 ft center to center) but I suspect that with all of them on, there will be enough light from several directions to eliminate most dark or shadowy spots.

In the layout in post #6 above, the large aircraft doors are to the right (east) and the 12w x 14h sectional door is to the left (west)(E and W walls are the endwalls) and the peak of the roof runs left to right. on the top (north) there is a 10x10 rollup door about mid way(N and S walls are sidewalls), and in the upper LH corner (NW) is the "shop" area, two wooden workbenches (16ft) along the north wall, and running parallel to these is another row of metal workbenches (about 18ft) with a 4 ft aisle between them.

Here is the build web pages for the building (from fall of '99) Beware, for reasons I do not understand, my web pages cause Netscape v.8 to crash and close. It does not affect Explorer or Navigator v.7. Sorry about the ads, thats what you get with free sites.

http://charles-dusty.tripod.com/hangar.html

Charles

Update..............

Charles (in GA) said:

I hung the ballast on the C-clamp and fitted the reflector (difficult considering it is 22 inches in diameter and nearly as high, installed a light bulb and fired it up. I let it run for several hours and after dark I turned out all other lights and observed the pattern. I did feel the ballast for heat, and while it was quite warm to touch, it was not hot enought to burn me. I could have used one of those IR temp measuring devices, gotta look into that, could find all kinds of uses for it.

Click to expand...

One of my coworkers has a RayTek Mini Temp IR temperature measuring device. He loaned it to me and I tried it this evening on the MH light I had previously mounted (temporarily)

I found that the hottest portion of the ballast housing was 160F and nearby areas of the ballast housing were about 145F. The remainder of the cast aluminum housing was about 125F and the electrical junction box was between 100F and 110F. The fixture was 55F in the unheated building before I turned it on. I measured the temp after about 4 hours of steady operation. Luckly I won't need these lights in the daytime, because in the summertime the temps up high in the building are probably 150F or more.

Gotta get me one of those IR temp devices, I can see how they could be very useful.

Charles

bmwpower said:

Good you stuck with the 400's. The 250's definitely would not have lit things up enough.

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Man I enjoy my 4 400's! We've had a lot of houseguests over the holidays hence lots of garage tours. Everyone comments on the amount of light! I just pulled the racecar out of storeage and into bay 3. Job one is disassemblying the entire ventilation system to root out nesting rodents. Not fun but the light was nice!