NFPA 10 requires that someone never has to travel more than a set distance to reach an extinguisher, and that maximum travel distance, combined with your floor area and hazard classification, is what actually determines the count.
For most ordinary commercial occupancies, that maximum travel distance is 75 feet. Picture a circle with that radius drawn from every extinguisher location. Every point on your floor plan needs to fall inside at least one of those circles. A large open warehouse floor needs more units spread across it than a small office suite of the same square footage, simply because of how the geometry works out.
Yes. Higher-hazard occupancies get shorter travel distances and sometimes require larger or additional extinguishers, since more can go wrong faster in those spaces.
A commercial kitchen with active fryers is treated differently than a quiet storage room next door. The kitchen needs its own Class K coverage in addition to whatever else the building requires. Mechanical rooms, paint booths, and areas with flammable liquid storage typically call for their own dedicated unit regardless of whether they’d otherwise fall inside another extinguisher’s coverage circle.
Most small offices and retail spaces end up needing somewhere between one and a handful of units, while larger or higher-hazard properties need considerably more, spread across the floor plan rather than clustered near the entrance.
This is exactly why extinguisher placement gets assessed on site rather than quoted over the phone from a square footage number alone. Layout, hazard type, and how the space is actually used all factor in.
A quick way to spot a placement problem yourself: stand in the farthest corner of any room and see if you can spot an extinguisher without walking more than a few dozen steps. If you can’t, that’s usually a sign the coverage needs a second look.
A quick site visit settles how many units your property actually needs and where they should go.