T5HO in 40'x 60'

[barnjunkie]

These are Metallux (Cooper) HBL series 4 Bulb T5ho. 220watts but I have 12 fixtures total. The total lumen output per fixture is 20,000 x 12 = 240,000.

240,000 lumens/2,400 sq Ft = 100 lumens/ft2. I would not want to go with less. What's the recommended lumens?

 

[Platonic Solid]

It doesn’t quite work that way. You’re getting about 16,800 Lumens out of each fixture. Using an estimated 13ft from floor to fixture face and surface reflectance of: 50% Ceiling, 60% Wall, 20% Floor, you’ll achieve an average of 68 lumens at the floor. It’ll be much higher directly beneath the fixture and lower between them.

You’re using a high bay fixture for a standard lighting application, thus you get glare. Looking at the 2 fixtures to the left and right of the garage door, you can make out the beam spread pattern on the wall. In a properly lit space it should not be this defined.

Your average 68 lumens would be fine if it was evenly distributed. It could be worse, but it could also be better. As discussed in this thread using the Cooper/Metalux 4 lamp F32T8 HBL-432-N-UNV-EB81/PLUS fixture.

Qty.20
Garage: X,Y = 40 x 60
Fixture Arrangement: X,Y = 4 x 5 (fixtures parallel with 60ft)
Spacing: X,Y = 10 x 12ft (fixture center to center)
Lumen Yield = 96 lumens

 

[barnjunkie]

Good points Platonic, the 68 lumens is probably closer to the actual number. Don't get me wrong, I'm not changing anything at this point (lot of money, blood, sweat, and backaches to get here). But I think if I was going to do it all over again, I probably would go with the T8ho and put more fixtures in.

The 14ft ceiling is still a little low for high bay - they sure look cool though.

I think once the concrete is poured, I'll be in good shape with more reflectance coming from the floor.