FENZ described the electrical installation at the farm shed as being old.
Prior to the fire, a welder had been plugged into a single-phase socket-outlet. The fire occurred sometime after the welding had been completed when the shed was unoccupied. The farmer who had been welding in the shed earlier that day reportedly told FENZ that this welding had caused the overcurrent protection at the switchboard to operate several times during that day.
The FENZ report determined the cause to be electrical in origin due to the damage found to the installation conductors at the scene. This was an indication of high temperature electrical arcing having occurred and was likely to be the cause of the fire. The earlier overloading of the electrical installation reported was considered to have been a significant contributory factor.