To ensure adequate shop lighting without shadows or dark spots, use these simple formulas to determine fixture locations.

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To ensure adequate illumination without shadows or dark spots, use these formulas to determine fixture locations.
Note: These formulas assume the use of continuous rows of two-lamp fluorescent fixtures.

• Measure (A), the distance from your main work surfaces to the ceiling (or to the desired height of suspended fixtures— usually 8' to 10' above the floor).
• The distance between fixtures (B), should be equal to or no more than 1.5 times (A).
• The distance between a fixture and the wall (C) should be no more than one third to one half (B).

Let's translate that to a typical two-car garage shop that measures 24x24' with a 9' ceiling and work surfaces 36" high. We'll use 16'-long rows of fixtures (either two 8' or four 4' placed end-to-end):
A=72" or 6'
B=72"x1.5=108" or 9'
C=108"x.5=54" or 412 '
If we place two rows of fixtures 9' apart (B), they'll each be 7 1/2' (C) from the side walls—way more than the 412 ' maximum. The sides of the shop will be too dark.
If we center one row, then add two more rows spaced 8' apart (B=8), then the outer rows will be 4' (C=4) from the walls. This layout lights the shop well.