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NFPA 10 Fire Extinguisher Spacing Made Simple

By Frank Jones··3 min read

NFPA 10 is the bible for fire extinguisher placement. But it's written in fire code language that makes most people's eyes glaze over.

Here's what those spacing rules actually mean.

The Core Concept: Travel Distance

Forget square footage calculations. NFPA 10 cares about one thing: how far someone walks to reach an extinguisher.

Think of it as drawing circles around each extinguisher. These circles can't have gaps.

Class A Spacing (Ordinary Materials)

The Rule

Maximum 75 feet travel distance to any Class A extinguisher.

What This Means

  • Measure actual walking paths, not straight lines
  • Account for walls, furniture, and obstacles
  • Every spot in your building must be within 75 feet of an extinguisher

Real-World Example

A 200-foot hallway needs at least 3 extinguishers:

  • One at each end (covers 75 feet each way)
  • One in the middle (covers the gap)

Class B Spacing (Flammable Liquids)

The Rule

Maximum 50 feet travel distance to Class B extinguishers.

Why It's Shorter

Flammable liquid fires spread faster. People need quicker access to extinguishers.

Common Applications

  • Vehicle service areas
  • Paint storage rooms
  • Facilities with fuel tanks

Class K Spacing (Cooking Oils)

The Rule

Maximum 30 feet travel distance in commercial kitchens.

The Reality

Most commercial kitchens need multiple Class K units because:

  • Large cooking areas exceed 30-foot coverage
  • Different cooking stations need dedicated protection
  • Fryer areas often require their own units

Special Distance Rules

High-Hazard Areas

Some locations get shorter travel distances:

  • Extra-hazardous areas: May be reduced to 50 feet for Class A
  • Light-hazard areas: Might allow up to 75 feet

Obstructed Paths

Travel distance increases if:

  • You must go around permanent barriers
  • Doorways create bottlenecks
  • Stairs are involved in the path

The Math Made Easy

Step 1: Map Your Space

Draw your floor plan with all permanent walls and obstacles.

Step 2: Mark Potential Locations

Identify spots where extinguishers could go (proper height, accessibility).

Step 3: Draw Coverage Circles

  • Class A: 75-foot radius circles
  • Class B: 50-foot radius circles
  • Class K: 30-foot radius circles

Step 4: Check for Gaps

Every area must be inside at least one circle.

Common Spacing Mistakes

Straight-Line Measuring

Wrong: Measuring 75 feet "as the crow flies" Right: Following actual walking paths

Ignoring Obstacles

Don't assume people will climb over desks or equipment to reach extinguishers.

Mixed Classifications

If you have both Class A and B hazards, use the shorter distance requirement.

Multi-Floor Buildings

Each floor is calculated separately. Don't assume someone will run upstairs during a fire.

Stairwell Strategy

Place extinguishers at:

  • Top and bottom of each stairwell
  • Landings in long stairwells
  • Near stairwell entrances on each floor

Working with Existing Buildings

Retrofit Challenges

Older buildings often have:

  • Limited mounting options
  • Unusual layouts that complicate spacing
  • Historical restrictions on modifications

Creative Solutions

  • Use wheeled extinguishers in large open areas
  • Mount units on structural columns
  • Consider recessed mounting in high-traffic areas

Professional Assessment

Consider hiring a fire protection professional if:

  • Your building has complex layout
  • You're dealing with multiple hazard classes
  • Local codes modify NFPA 10 requirements
  • You're facing inspection failures

NFPA 10 spacing isn't negotiable. Fire marshals check these distances during every inspection. Get it right from the start.