Voice of Experience: Distribution Cover-Up: Why Wouldn’t You Use It?
Over the next few installments of “Voice of Experience,” I’ll be reviewing some accidents that have taken place in the electric utility industry. I’ve had many requests for information about incident investigations and would like to share some details in hopes of preventing similar accidents in the future. Distribution cover-up will be the focus for this issue’s column.
Approximately half – or even more – of accidents that result in flashes and electrical contacts are the result of poor cover-up or total lack of rated protective cover. Why would a lineworker not take the time to install protective cover that would assure a safe work area? According to statistics and accident reports, the industry suffers an average of one contact or flash every week. That needs to stop.
Investigations into many accidents, some of which involved fatal contact with system or source voltages, have revealed that failure to cover up all differences of potential in the immediate work area was the common denominator in most flashes and contacts. If you are or your company is following the minimum requirements found in OSHA 29 CFR 1910.269(l), “Working on or near exposed energized parts,” it is simply not enough to ensure an employee is totally protected from differences of potential in the work area.
The human body essentially is a 1,000-ohm resistor in an electrical circuit. When a lineworker fails to cover energized parts as well as differences of potential in the immediate work area, as little as a 50-volt AC electrical source may enter the body. If the current path crosses the heart, as few as 40 to 50 milliamps can induce atrial fibrillation, cause the heart to stop sinus rhythm and electrocute the worker. The industry is quite familiar with medium-voltage contacts but many times lacks respect for low-voltage contacts that can be just as fatal.
Before the Accident
There’s an accident I’m aware of that occurred several years ago, but it could just as easily have happened today. The reason for the accident was a primary voltage contact between an energized primary and a new conductor being installed on a reconductoring project.
The crew had been working on the mile-long project for more than two weeks. All the new poles had been set and framed, and old equipment and conductors had been transferred and set off on layout arms to new poles. The crew had used 10-foot wooden arms to spread, and they had attached fiberglass layout arms to extend energized phases, in order to allow working room on the inside of old, energized #2 ACSR phase conductors. All poles had been framed with new polymer fiberglass arms and hardware, and roller blocks had been mounted on insulators. The new 397-MCM conductor had been pulled, sagged to final sag and allowed to settle overnight. The crew had worked late the day before to get the conductor installed and sagged to tension with a dynamometer. The crew had planned to let the initial sag sit overnight and start moving the new wire to the insulators the next day. All new conductors were grounded on each end of the pull to the system neutral.
The crew’s normal work hours were from 7 a.m. until 5:30 p.m. The day of the accident, the employee who would wind up being injured – who I’ll refer to in future paragraphs as the “injured employee” – did not arrive at 7 a.m. The general foreman called and woke him up, and the employee explained that he had overslept. He asked the foreman to have an apprentice lineworker drive his bucket truck to the job site, and the employee would drive his personal vehicle to the site and meet the crew there.
The crew arrived on the job site roughly 30 to 45 minutes later. They had a quick job-planning meeting and decided who would set up on which pole. As revealed in the later investigation, they did not complete a job briefing as required by regulation.
The apprentice lineman parked the injured employee’s bucket truck at the midway point of the pull so he could start in the middle and work his way toward the dead end of the new conductor. Road signs and other traffic control measures were set up as required by the Manual on Uniform Traffic Control Devices. All three bucket trucks were set up to start transferring the new conductors from roller blocks to insulators and secured with preform ties.
About 20 minutes after all the equipment had been set up and the other two linemen had started on nearby poles, the injured employee showed up at the job site and parked his personal vehicle near his bucket truck. The apprentice was busy preparing preforms. The injured employee immediately donned his fall protection, climbed into the bucket and ascended to the working position. He never reported to the general foreman, and the apprentice was the only crew member he spoke to before going to work.
At the time of the accident, the injured employee’s truck was set on the road side of the pole. The energized conductors had been set off two phases to the field side and one energized to the road side on layout arms. The three new grounded conductors were in rollers on the inside of energized conductors. There were approximately 42 inches between the energized roadside phase and the new grounded roadside phase.
The injured employee had not asked for any cover-up, nor did he have any in his bucket, but the apprentice had laid three 30-kV line hoses on the back of the bucket truck. This accident occurred on a 12,470-kV nominal system voltage distribution line. The injured employee ascended to the spread conductors and went in between the energized 7.2-kV conductor and the newly installed roadside 397-MCM conductor. Wearing leather work gloves, and with no rated insulated rubber goods on the energized phase, the injured employee opened the roller block. He placed his left hand on the new conductor to steady the bucket and attempted to get in a better position to raise the conductor from roller to insulator. The injured employee then backed up approximately 12 to 18 inches and raised the bucket until his right shoulder contacted the 7.2-kV energized phase. The apprentice had gone back to putting out materials and never saw the accident.
The line was on “hot line tag” – one shot and it operated immediately. The injured employee received a severe contact burn, with entry through the right shoulder and exit through the left hand. The accident resulted in a loss of the employee’s injured right arm from the shoulder.
The remaining facts are that the crew members were not rushed, and that protective cover was available but simply wasn’t used. In addition, rubber gloves were in the bucket, but the injured employee didn’t use them.
What went wrong? How could this incident have been prevented? What regulations and safety rules were not adhered to? And how can we use this information to prevent similar accidents in the future?
Please use this article as a tool to prompt thought and conversation within your safety meetings and accident prevention programs. And feel free to send Incident Prevention your thoughts and answers to the above questions. The point of the article is not to place blame, but rather to illustrate how accidents can occur. Remember, almost no one intentionally puts themselves into this type of situation, but nonetheless, similar events continue to harm utility employees every year.
About the Author: Danny Raines, CUSP, safety consultant, distribution and transmission, retired from Georgia Power after 40 years of service and opened Raines Utility Safety Solutions LLC, providing compliance training, risk assessments and safety observation programs. He is also an affiliate instructor at Georgia Tech Research Center OSHA Outreach in Atlanta. For more information, visit www.electricutilitysafety.com.