I'm building my dream shop, 50x50x20 steel building. Does anyone with a similar sized building have any feedback on lights for something this size??

 

In Florida, you should not have the usual trouble with cold weather lighting.

A key factor on the type and amount of light you need is whether you have a flat white ceiling and walls; basically something that reflects light vs. absorbing it. With a dark ceiling you'll either need more lighting, or to bring the lights down closer to the work.

The amount of light you want depends to some degree on your age and budget. As I have gotten older I need more light to see what I'm doing. If it were me, I'd put in 6 continuous rows of 8 foot tandem channel fluorescent fixtures (on 8 foot centers). There would be 6 fixtures per row. Get good ones with electronic ballasts and t8 tubes, so they don't hum. Arrange the rows parallel to the direction you'll be parking the vehicles for service. Use tubes with a 5000K color temp for the best "pupil lumens" per watt. This will give you around 120 foot candles throughout the shop. Nice and bright.

For examples of this kind of lighting, walk into the typical grocery store, Target, Wall-Mart, etc, and look up.

With your high ceilings, you can consider industrial style "high bay" fixtures, such as are typically used at a Home Depot. Metal halide is the most reasonable choice here.
One big disadvantage of these is their long warm-up time, which is a problem if you just want to dash into the shop to grab some tools. The other disadvantage is you can't buy these at big box stores, so prices are higher unless you are "in the trade" or know somebody that is. On the other hand, you need far fewer fixtures, and they come with paraboloic reflectors which is a good thing if you have a dark ceiling.

You need around 50 * 50 * 120 / (0.70) gross lumens for 120 fc at working height. Call it 425000 lumens. Divide that number by the gross lumens of the fixture to get a ballpark on the number of fixtures needed.

 

I have a 40x80x14 eve height metal building. It is insulated, so the ceiling and walls are white. I have fluorescent in half of it and metal halide in the other half. There is no comparison. The metal halide is SO MUCH BETTER. I have one fluorescent in this area that comes on with them. It provides enough light to run in and grab something without having to wait for the halides to come on.

 

I'm curious -- what's the size and arrangement of fixtures in each of the two halves of your building? The metal halides may be "SO MUCH BETTER" because they provide many more total gross lumens in that half than the fluorescents do in theirs.

Or maybe not --Metal Halide light is known to have good "pupil efficiency", whereas not all fluorescent tubes provide the same. The total fixture efficiency (lumens per watt) is better for fluorescent than halide, but they are pretty close. There may be something "better" (at least for you) about halide for shop work even with the total lumens the same.

Retailers care a lot about "brightness". A light and bright store sells more product than a dingy one. There seems to be a relatively even split between halide and fluorescent in retail -- fluorescent being more prevalent in "low" ceilings (below 15 foot), and halide more prevalent in "high" ceilings (above 15 foot), but there is some crossover for anything more than about 10 feet. So for stores, at least, it isn't a slam-dunk choice between the two types.

So I'm curious what makes the two types so different for you...

 

Thank you for the insight. I'm definitely at an age where I need the additional light and that situation probably won't get better.

Possibly a mix of the two, a few fluorescents for the quickies and the halides for the all day/night stuff.