Inspection Detail

Inspection: 300573896 - Leonard Hudson Drilling Co. Inc.

Inspection Information - Office: Lubbock Area Office

Investigation Summary

A centrifuge at a drilling site had a ground fault. The control box for the centrifuge had a splice with two No. 6 AWG conductors and one No. 10 AWG conductor. The conductors had been connected by a wire nut designed for No. 12 AWG conductors. The wire nut became lose during the operation of the equipment and dropped to the bottom of the box. The No. 10 conductor also came lose and contacted a grounding lug. In addition, the fuses protecting the circuit were rated higher than permitted for the circuit. The centrifuge was grounded to the portable generator used to supply power at the site, but it was not bonded to the drill rig. (The generator was connected to a grounding rod used for lightning protection.) The centrifuge was also resting on a plastic sheet, further isolating it from the drill rig. Lastly, a silicone joint had pulled away from the box opening about 75 to 100 millimeters. An employee was standing on the ground near a ladder used to access the platform for the centrifuge. He was electrocuted when he touched the ladder, which had been energized by the ground fault in the centrifuge.

Keywords: E GI V, ELECTRICAL, ELECTROCUTED, GROUND FAULT, EQUIPMENT GROUNDING, ELECTRIC CONDUCTOR, ELECTRICAL BOX, ELECTRICAL SPLICE, OIL RIG