NFPA 101 Life Safety Code sets the illumination levels for emergency egress. Miss them and the project doesn't pass inspection. Here are the numbers and how they drive fixture layout.
The numbers
- 1 footcandle (10.8 lux) average along the egress path, measured at the floor
- 0.1 footcandle (1.08 lux) minimum at any point along the egress path
- Maximum-to-minimum uniformity ratio of 40:1 (the brightest point may be at most 40× the dimmest)
- 90 minutes minimum duration of emergency operation after a normal-power failure
- Emergency illumination must activate within 10 seconds of AC failure (UL 924 requires much faster — microseconds — but NFPA's floor is 10 seconds)
Where these rules apply
Every means-of-egress in every building classified as commercial, assembly, educational, health care, or industrial. That is, essentially every non-residential building in the U.S. State and local jurisdictions often adopt NFPA 101 by reference in their building codes.
What 'average' really means
The 1 fc average is computed across the full egress path, not at one measurement point. A photometric model in AGi32 or DIALux places measurement grid points every 2–3 ft along the egress path and averages them. The 0.1 fc minimum is a hard floor at every grid point individually — no dark spots.
Why uniformity matters
The 40:1 max/min rule prevents specifiers from 'winning' the average by placing one very bright fixture and letting the rest of the path stay dim. Emergency egress has to be uniformly lit so people don't walk from a bright zone into a relatively dark zone and lose their orientation.
Sage and NFPA 101
Every Sage photometric .ies file is tested to IESNA LM-63 and modeled correctly by AGi32/DIALux/Visual. The Coverage Estimator on this site uses Sage spec sheet spacings (derived from 1 fc average @ 9–10 ft mounting) to give you a back-of-envelope count. For the stamped submittal, run the .ies files through your photometric software.