Don’t Touch: Electrocution fatality report

0620_Safety

Recently a worker was fatally injured after being electrocuted through indirect contact with a 7,200 volt overhead power line. In an anchor-setting process, a boom truck with an auger attached was turning a utility pole anchor in preparation for a utility-pole replacement. During the process, the anchor wobbled and the extended boom contacted the overhead power line.

Apparently unaware the boom was in contact with the overhead power line, the victim grabbed the energized anchor with both hands in an attempt to stabilize it and remained in contact with the energized anchor until the boom was moved away from the power line. Electrical current moved through the victim’s body from his hands to ground through his feet.

The victim was a laborer on a three-person crew. He had been working on this electrical service division crew for about four months. The victim had no formal or documented training in the electric-utility-construction industry; all training was provided on the job by the municipality.

It was reported that overhead power line safety was discussed on the morning of the incident. The victim’s routine responsibilities included monitoring and controlling the auger/anchor joint and the sway during drilling.

The equipment used in the case was a powered boom truck designed for hoisting and setting utility poles. It had recently been inspected and passed its semiannual dielectric (a nonconductor of electrical current) test.

However, the boom’s design does not accommodate for the complete isolation of the truck, only a portion of the boom. Therefore, electric current passed from the point of contact down through the auger and victim to the ground. This was the town’s first workplace fatality.

The municipal electrical service provides power to approximately 5,000 homes and businesses in the area. As part of a system-wide service upgrade, a replacement utility pole was to be set to support an existing power line. Then a guy pole was to be set approximately 30 feet from the pole and an anchor was to be set approximately 18 feet from the guy pole.

To install the anchor, the distal end of the boom truck auger is fitted with a coupling, allowing the attachment of the eye ring on the end of the 6-foot anchor. The auger motor rotates and the anchor is slowly screwed (set) into the ground.

As the anchor was being set, it broke. The crew was sent to the material yard to get a second anchor, and the crew supervisor left the scene to check on other work. Then the crew was back at the site with an 8-foot long, 10-inch wide, auger-end anchor.

Shortly after, the crew located the anchor position and noted there was a clearance issue due to the longer anchor and the proximity of the boom to the overhead power line. The crew began to dig a 19-inch deep, 12-inch wide pilot hole to accommodate the longer anchor and maintain clearance from the power line.

The ground crew then connected the anchor to the end of the auger and placed the anchor into the hole. Because of the angle of the required hole, the rotating auger/anchor pivot point began to wobble, causing the boom to sway. The victim went over to the anchor and grasped it with both hands, likely trying to stabilize it.

The boom truck operator saw the victim approach the anchor and called to him to stop. The victim, despite the attempt to warn him, reached for the anchor at the same time the boom operator heard a “zapping” noise and saw the victim holding the anchor.

Electrical current moved through the victim’s body from his hands, through his torso and to the ground. Realizing that the victim was in contact with the energized anchor, the operator moved the boom away from the power line, and the victim fell to the ground.

In an effort to prevent similar incidents from occurring, investigators made the following recommendations:

  • Employers should conduct a job site survey to identify potential hazards and develop and implement appropriate control measures for these hazards.
  • Employers should follow existing OSHA regulations and safe work practices concerning operating cranes or equipment in close proximity to overhead power lines and take steps necessary to de-energize or insulate power lines before work begins.
  • Employers should ensure that when working near a high-voltage, overhead power line, in situations in which visibility could be obstructed or clearances difficult to determine, an observer is used to help the operator maintain the required clearance.
  • Employers should develop, implement and enforce a comprehensive written safety program for all workers, which include training in hazard recognition and the avoidance of unsafe conditions. A written plan should require training for all ground crew in electric utility operations.
About the Author

Tom O'Connor

Safety Columnist

Tom O'Connor is safety and regulatory affairs manager for Intec, a safety consulting, training and publishing firm that offers on-site assistance and produces manuals, training videos and software for contractors. Reach him at toconnor@intecweb.com.

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