I just signed the lease on a new (to me) 6,000 square foot shop/barn for my business. It's definitely going to need some work. I really want to get some good lighting going in the main area, which is currently dark. The bay down the middle is approximately 30'x100' and 18 feet tall. It currently has some old metal halide lights, but only one of them works. It also buzzes like a bee hive and drives me crazy.
So the question is, what would be the best lighting here, on a budget? Would the ceiling be too tall for T8 fluorescents? I don't really want to invest in T5. Would I be better off with some high bay MH lights like what is there now? Would 1000w each be too much?
With that much ceiling height (and, presumably, a similar mounting height for the fixtures), the type of fixture will be more important that the type of light source, per se. It's all about the reflector and the focusing device(s), not what originally makes the light. For that application, you want something designated as a "High Bay" fixture. Such fixtures are available using all sorts of light sources: T5, T8, MH, even CFL (tho' not as commonly). They can also be rather pricey; but they don't necessarily have to be.
I suppose I need to put them on several different switches so that I don't have to burn 5-10 kilowatts at a time.
That's (almost) always a good idea. And you probably ought to use more banks/switches than you (now) think you need. This is something of a stab in the dark (NPI); but with no other information to go on, I'd suggest at least three banks for the general-purpose lighting of the main area: one with a minimal number of fixtures, to be used as your low-level "walk through" lighting, a second bank with about 1/3 of whatever is left, and a third bank with the other two-thirds. This will yield at least four different selectable brightness levels, yet still retain semi-even illumination at all times, assuming you pay attention to the spacing between each same-bank fixture as you wire things up. Some larger fixtures (such as some six- and eight-tube fluorescents) are already set up to be wired as two banks; but they generally split them up into two same-size banks, so you'll still need to get a bit creative if you want to take the 1/3 vs. 2/3 approach.
I also have a bunch of smaller work areas, and an upstairs area, which will have lesser lighting for smaller projects and storage.
Those areas will, of course, require separate solutions.
The current electrical system is very old, hacked up, and dangerous, so I will be running new wires to the breaker box for this.
How is the breaker panel itself? And does it (and the incoming service) have sufficient capacity for everything you're going to want to do (including tools & machinery, in addition to the lighting)?
What will you be doing? With the open black space above the lights and the walls/etc. being what they are, it would take a ton of light to light "properly".
Not necessarily. As noted above, it all depends on the TYPE of fixture, and how well it directs its output downward, as opposed to letting it scatter everywhere.
I would go with cheap T8 shop lights - you're going to need a lot of them. They will do okay at 18'.
I'd expect those to do better than open-tube strip lights, but not as well as a fixture expressly designed for such mounting heights.
I would go with low bay lights as it's definitely a low bay, and you really need it spread out a bit...
You've got that backwards.
"High Bay" denotes a mounting height
above about 12 (sometimes 15) feet; "Low Bay" denotes lower mounting heights (typically 8-10 feet).
Can you get (even partial) credit against the rent for leasehold improvements?
I sell vintage outboard motor parts. Most of my work is taking apart old outboards and cleaning/refurbishing all the parts. I agree, there is just going to be a big dark hole in there. I'm going to try and put some white paint on every surface I can. What if I hung fluorescent lights down from the ceiling a ways, maybe around 12'? I don't really need the height. Would lowering them a few feet be worth the trouble?
Depends on how much trouble you're talking about. The lower the fixture, the more the fixture will need to disperse its output over a wider area. That in turn will make it depend more on the reflectivity of the surrounding surfaces (i.e., that white paint) to produce relatively even, shadowless, illumination. With little (or no) surrounding surfaces to paint, this approach tends to be ineffective.
I would really like it if the whole thing was lit up like a paint booth, but realistically, I could never afford to run all that. My shop now is lit with T8s at less than .5 watts/square foot and it drives me crazy. Always lots of shadows, I have to use a flashlight inside the shop all the time.
With the staggered-brightness approach I outlined above, you can have the best of both worlds -- or at least, as close to it as practically achievable.
