An electrical fire involves energized electrical equipment and presents a unique danger. While the natural impulse is to grab water, attempting to extinguish this type of fire with water is a profoundly dangerous mistake. This common error can instantly transform a localized emergency into a life-threatening disaster.
Why Water Is Dangerous
The most immediate threat when applying water to an electrical fire is the risk of electrocution. Standard tap water is not pure \(\text{H}_2\text{O}\); it contains dissolved minerals, salts, and ions such as calcium, magnesium, sodium, and chloride. These dissolved solids make the water an effective electrical conductor, offering a path for the current to flow.
When a stream of water is directed at energized electrical components, it completes a circuit between the live wires and the person holding the container. The water becomes a direct, highly conductive path, allowing electricity to travel from the fire and into the individual’s body. The resulting electric shock can cause severe injury or death by disrupting the heart’s rhythm or paralyzing respiratory muscles. Even a small amount of dissolved solids is sufficient to make the water conductive enough to carry a lethal current.
How Water Spreads the Fire
Beyond the risk of electric shock, the physical interaction of water and fire can actively spread combustion to surrounding materials. When water hits the intense heat, it instantly flashes into steam. Water expands by a factor of approximately 1,700 times its liquid volume when it vaporizes.
This rapid expansion creates an explosive puff of steam and pressure that can forcibly eject burning debris and molten material outward. This splattering action propels flaming particles onto nearby combustible items like curtains, furniture, or paper, igniting new fires away from the original source. Furthermore, water can travel along unexpected pathways, following wires, conduits, or seeping through walls and floors. This liquid flow can carry the electrical current to previously unaffected areas, creating new short circuits and igniting fires far from the initial flame.
Safe Steps for Extinguishing an Electrical Fire
The first step in addressing an electrical fire is to immediately cut the power source. Locating the circuit breaker panel or fuse box and switching off the circuit feeding the fire is the quickest way to remove the source of ignition. Only attempt this if the panel is safely accessible and does not require approaching the fire. Once the power is disconnected, the fire is no longer technically “electrical” (Class C) and can be treated as an ordinary combustible fire (Class A). However, using water is still not advised due to the lingering presence of energized components or the potential for splattering.
The correct tool for an energized electrical fire is a Class C fire extinguisher, which uses non-conductive agents to smother the flames. These agents are typically carbon dioxide (\(\text{CO}_2\)) or a dry chemical powder. The \(\text{CO}_2\) works by displacing the oxygen fueling the fire, while dry chemical agents interrupt the fire’s chemical reaction.
Using a Class C Extinguisher
To use the extinguisher, employ the \(\text{PASS}\) method:
- Pull the pin.
- Aim the nozzle low at the base of the fire.
- Squeeze the handle to release the agent.
- Sweep the nozzle from side to side until the fire is out.
If the fire is growing rapidly, the power cannot be safely disconnected, or if heavy smoke is filling the area, immediate evacuation is necessary. Do not attempt to fight a fire larger than a small wastebasket. Prioritize getting everyone out of the building safely before calling emergency services from a safe location. Even after extinguishing a small fire, call the fire department to ensure no smoldering embers remain hidden inside the equipment or walls.