Fire Protection and Prevention

Fire is a significant hazard on construction sites due to the presence of flammable materials, hot work, temporary electrical systems, and combustible building materials. OSHA 1926.150 requires fire protection programs on all construction sites. Understanding the classes of fire is essential for selecting the right extinguishing agent: Class A — ordinary combustibles (wood, paper, cloth, plastic); Class B — flammable and combustible liquids and gases (gasoline, propane, paint solvents); Class C — energized electrical equipment (electrical panels, wiring, motors); Class D — combustible metals (magnesium, titanium, sodium — relatively rare); Class K — cooking oils and fats (kitchen fires, not common on most construction sites). Using the wrong extinguisher can spread the fire or create additional hazards — water on a Class C fire conducts electricity back to the user.

Portable fire extinguisher operation uses the PASS technique: Pull the pin (this unlocks the operating lever), Aim the nozzle at the base of the fire (not the flames), Squeeze the handle to discharge the extinguishing agent, Sweep the nozzle from side to side at the base of the fire. Most portable extinguishers provide only 8-15 seconds of discharge — use them only on incipient (small) fires. Never fight a fire that is larger than a waste basket, or that is spreading, or that involves stored flammables. Extinguishers must be within 75 feet of combustible materials, inspected monthly, maintained annually, and hydrostatically tested every 5-12 years depending on type. ABC dry chemical extinguishers are the most common type on construction sites.

Hot work (welding, cutting, brazing, grinding) is a leading cause of construction site fires. Hot work permits should be required before any spark-producing operations. Requirements: remove or protect combustibles within 35 feet of the work area, confirm a fire extinguisher is present, assign a trained fire watch to monitor the area during hot work and for at least 30 minutes after completion. Flammable liquid storage: liquids with flash points below 100°F (flammable liquids) must be stored in approved safety cans with flash arresters, away from heat sources. No more than 25 gallons of flammable liquids may be stored in a single room without sprinkler systems.