NFPA 72 code sections · Emergency Communication Systems
Corridors: 15 cd strobes, 15 feet from the ends, 100 feet apart
In a corridor no wider than 20 feet, visible appliances can follow the corridor rule instead of the room tables: 15-candela strobes, within 15 feet of each end, with no more than 100 feet between appliances. Any time the corridor turns, is interrupted by a door or other obstruction, or steps up or down in elevation, it is treated as a separate corridor with its own end-of-corridor strobes. If the corridor is wider than 20 feet, you're back to the room spacing tables.
NFPA 72 reference
Chapter 18 — Notification Appliances
18.5.5.6 Corridor Spacing (18.5.5.6.1 corridors ≤ 20 ft wide; Table 18.5.5.6.4 15 cd, ≤ 15 ft from ends, ≤ 100 ft apart; 18.5.5.6.5 interruptions treated as separate corridors)
References use NFPA 72 2019/2022 numbering — section numbers can shift between editions, so confirm in the edition your AHJ has adopted.
On the job
A school corridor is 220 ft long with a set of cross-corridor fire doors at the midpoint. The drawings show three strobes evenly spaced at 110 ft — too far apart, and the doors split the corridor in two anyway. The corrected layout treats each 110-ft half as its own corridor: a strobe within 15 ft of each end of each half, so four strobes total, each pair under 100 ft apart.
Quick check
1. The corridor spacing rule applies to corridors no wider than:
2. Under the corridor rule, strobes must be within how far of each end?
3. A set of cross-corridor doors means:
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