The operator of a fully loaded truck saw flames coming from a resistor grid box. The operator stopped the truck and activated the e-stop and fire suppression system. The fire suppression system didn’t adequately reach the resistor grid box to fully extinguish the fire so a water truck was called to apply water, which ultimately extinguished the fire.
Recommendations to industry: Resistor grids of haul trucks operate at very high temperatures. It is important that these areas be correctly maintained and and kept free of rubbish and debris. Electrical faults, loose electrical connections and damaged electrical wiring are common fire sources on mobile plant.
Mines should implement systems that consider the electrical wiring recommendations of AS/NZS 4871.6:2013: Electrical equipment for mines and quarries – Diesel powered machinery and ancillary equipment. Fire risk assessments, detection and suppression on mobile plant should be in accordance with AS 5062 Fire protection for mobile and transportable equipment.