A 44-year-old female (victim) tree trimming/removal worker was electrocuted when she made indirect contact with an 8,000-volt overhead power line. The incident occurred as a tree was being prepared for removal from beneath overhead primary (8,000-volt) and secondary (240-volt) power lines at a private residence. The secondary line was 6 feet below the primary line.
A boom truck equipped with a one-man fiberglass bucket was being used to trim the tree. The west side of the tree was trimmed without incident. Because of heavy rain the night before, the truck could not be moved to the other side of the power lines to trim the other side of the tree. The operator of the bucket, therefore, attempted to maneuver it between the primary and secondary lines. The boom made contact with the upper 8,000-volt line just as the ground worker was reaching for a chain saw sitting on the truck. The truck became energized when the boom contacted the primary line and the worker, completing the circuit to ground, was electrocuted. Despite quick medical response, she died from the injuries she received.
With the many hazards facing tree service workers, it is unconscionable that in today’s industry a tree service company would not offer, at a bare minimum, a monthly safety meeting. The risks are too high and the penalties too severe not to give full attention to the dangers inherent in the tree service business. The first step in any safety process is to acknowledge that the risks are real and the remedies are readily available.
The Occupational Safety and Health Administration (OSHA) requires companies with more than 10 employees to have monthly safety meetings, and companies that have fewer than 10 employees must organize a safety committee with at least two employees. From OSHA: “Employees shall be trained in and familiar with the safety-related work practices, safety procedures, and other safety requirements in this section that pertain to their respective job assignments. Employees shall also be trained in and familiar with any other safety practices, including applicable emergency procedures (such as pole top and manhole rescue)
I’d like to report that no one in the tree service industry died from electrocution last year, but that would not be true. Unfortunately, statistics on deaths in the tree service industry are somewhat ambiguous at best. Because of changes in reporting classifications, the tree service industry has been joined with other industries, such as the landscape industry, when analyzing this type of data. The Bureau of Labor Statistics (BLS) published their newest information on industry deaths for 2010, reporting that over 1 million people were employed in the shrub and tree service industry and 76 lost their lives due to electrocution.
The case study cited above describes the bucket as being made of fiberglass, what many might refer to as an insulated bucket, so those workers incorrectly assumed that contact with the pole would be safe – they were wrong. Although the bucket was safe, the metal boom was not. In addition, the example above notes that the worker was removing a chain saw from the truck. Tools should be unloaded before the boom truck is engaged. An unwritten rule (common sense rule) of safety around high-voltage power lines is to avoid contact with metal objects whenever possible. Finally, the case study shows that completing a circuit is deadly.
Tree service workers are familiar with the wooden crossbars near the top of many older telephone poles, but few realize what electrical components these crossbars hold, and the incredible amount of electricity that surges through these elements every second.
Figure 1 outlines the electrical components that are attached to a typical telephone pole. For our purposes, the three electric transmission wires, tagged 3 and 4 A, B and C, and the primary distribution lines, 6 and 9, are the wires that carry the greatest current, are sometimes knocked down during a storm, and are most responsible for death and serious injuries to workers. The A, B and C transmission wires carry high-voltage electricity from the power plants in three phases and then to substations, where the voltage is reduced. From the substations, the power is distributed by lines called feeders. The Primary conductor wires (6) carry electricity from the substations and are often supported by the crossbar. The multi-grounded neutral distribution line (8) provides a return path for the electricity. This distribution line is often connected to the ground wire.
Carrying upwards of 8,000 volts, these wires are a most serious hazard and must be avoided. The first safety rule when arriving to a site with downed power lines or when tree branches and a utility pole are interconnected is: De-energize the pole by calling the utility company first.
A 32-year-old male arborist was electrocuted when he came into contact with a 13,800-volt public utility power line while cutting down a large pine tree. The victim was tied off to the upper section of the tree by a safety harness and lanyard and was cutting branches. A co-worker, who was on the ground passing the branches through a chipper, heard a groan, and looking up saw that the victim had come in contact with the power line at the back of his neck. The victim appeared unconscious, and the power line was visibly arcing. The co-worker called for help, but subsequent rescue efforts were hampered when the tree itself became energized. It was not until approximately 50 minutes later that the power line was de-energized and the victim retrieved from the tree.
I will repeat myself because this cannot be said in a safety meeting too many times — always de-energize first. This tragic circumstance also shows that trees are conductors of electricity, and workers should never engage a tree when a power line has fallen into any part of that tree. Lastly, the tree service worker on the ground did not know how to make a rescue. These are all additional safety points that might be covered in monthly (or weekly) safety meetings.
The Tree Care Industry Association offers a wealth of information in safety training including information on holding safety meetings, as well as tailgate meetings; Electrical Hazards Awareness Program (EHAP), preparing workers for storm cleanup and awareness of electrical hazards on-site; offering a credentialing program (CTSP), to train safety coaches; publishing safety manuals, Best Practices for Crane Use in Arboriculture, Best Practices for Rigging in Arboriculture, Illness and Injury Prevention Program; and OSHA safety/compliance consultation.
A 35-year-old tree trimming crew leader (the victim) was supervising a crew assigned to clear fallen trees in an area where a 4,000-volt power line had been knocked down during Hurricane Hugo. After trees had been removed from the de-energized downed line, the crew returned to the truck while the crew leader inspected the job. During the inspection, the victim apparently stepped on the power line and was electrocuted. A subsequent investigation revealed that a gas-powered generator was being used to supply power to gas pumps at a nearby gas station. The main circuit breaker at the gas station had not been opened, therefore, electric current from the generator flowed back through the transformer and energized the downed power line at the work site [NIOSH 1989b].
When dealing with high-power lines, double-check; there are no second chances. Safety gloves and sleeves should be worn even after the lines have been de-energized. Human beings are resourceful; the person working for the gasoline company who started running the generator could not have known that their action put a life at risk. On-site, always assume that all wires are hot.
After a time, safety meetings, whether on-site or at the “barn,” can often become a series of repetitions on information that the crews have been warned about time and time again. Keeping the crew’s attention when discussing subjects such as personal protective equipment, bucket truck certification or hearing conservation can lead to worker apathy, and sometimes safety meetings turn into “bull sessions,” with more attention given to the coffee and doughnuts than on the presentation. Prevent this from happening by including a case study from the Center for Disease Control, such as the ones I’ve outlined above. The information from these case studies inevitably becomes very personal, because the workers can relate to these fellow arborists who have lost their lives due to negligence or some unforeseen happenstance. The workers will be engaged, because these studies could be about them. Each study also gives contributing factors and recommendations/discussions that you can use at your next safety meeting.
In 2010, 76 people in the tree service industry died by electrocution. With careful planning and enforcement of company safety standards and OSHA regulations, there need not be a single loss in 2013.