Derrickman / forklift operator entered the forklift and observed that the driver’s side outrigger was up. The operator failed to notice that the off side outrigger had been placed on the ground to serve as wheel chocks. He backed the forklift up, and then moved forward towards the mud storage area when he heard a pop. The off side out rigger had struck and cut the 480 volt power supply cable to the rig camp transformer. When the power supply cable was severed, the breaker was tripped. The operator jumped from the forklift unharmed.