The Hidden Hazards of Stray Welding Current: Lessons from the ‘Qualifier 105’ Fire

The National Transportation Safety Board (NTSB) has issued its final report on the investigation into the 2023 fire aboard the passenger vessel Qualifier 105 in Alaska.

The fire occurred on January 19, 2023, while the vessel was stored ashore for the winter at the Northern Enterprises Boat Yard in Homer, Alaska. The fire started in a stateroom below the main deck and was extinguished by the local fire department without any reported injuries or pollution.

The vessel, which was used for marine survey, oceanographic research, environmental clean-up, housing, and private charters, was declared a total loss valued at $1.2 million.

Although welders were performing aluminum hot work on the vessel before the fire, investigators ruled out the hot work as the cause, finding no signs of a fire during or after the welding activities. The investigation concluded that the fire was caused by an undetermined electrical source that ignited the stateroom ceiling. The extensive use of combustible materials in the ceilings and bulkheads of the vessel’s accommodation spaces contributed to the significant fire damage.

The NTSB report also highlighted the dangers of stray welding current.

“Stray welding current is a fault condition in which current goes through unintended conductors and back to the return terminal of a welding machine; it can cause fires by overheating wires,” the report said. “To avoid potential fires caused from stray welding current, maintenance personnel, owners, and operators should follow industry practice to place the work clamp (the return current clamp) of the welding machine as close as possible to the point of welding.”

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