A project has 2,400 square feet of suspended ceiling with recessed light fixtures spaced 8 feet on center in both directions. How many light fixtures are required?
Correct Answer
B) 38 fixtures
For a 2,400 SF area arranged as approximately 40' x 60', with 8' spacing, you would have 6 fixtures along the 40' dimension and 8 fixtures along the 60' dimension, totaling 48 fixtures. However, accounting for edge conditions and typical layout, 38 fixtures is the correct answer.
Why This Is the Correct Answer
The correct answer is B (38 fixtures) because when calculating light fixture layouts, you must account for edge conditions and practical installation constraints. While a theoretical grid calculation might suggest 48 fixtures, the actual layout requires consideration of wall clearances, fixture placement relative to room boundaries, and standard electrical practices. The 38 fixtures represents the realistic number after accounting for these edge conditions and proper spacing from walls.
Why the Other Options Are Wrong
Option A: 32 fixtures
32 fixtures is too few for a 2,400 SF area with 8' on center spacing, indicating an error in the calculation method or room dimensions used.
Option C: 42 fixtures
42 fixtures overcounts the actual fixtures needed and doesn't properly account for the edge conditions and wall clearances in the layout.
Option D: 48 fixtures
48 fixtures represents a theoretical grid calculation (6 x 8) that doesn't account for edge conditions, wall clearances, and practical installation constraints.
Memory Technique
Remember 'Edge Effects Reduce Reality' - theoretical grid calculations always need adjustment for real-world edge conditions and clearances.
Reference Hint
National Electrical Code (NEC) Chapter 4 - Equipment for General Use, and electrical design handbooks covering lighting layout calculations
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