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

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.

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