Respect the Power of Power Lines
It doesn’t matter whether you work in an urban, suburban, or rural setting. Look around, and you’ll see that electric power transmission lines are a familiar part of the landscape. From the wood poles that deliver service local customers, to the giant towers carrying high-voltage, high-tension conductors around the nation’s power grid, power lines also present a significant hazard to workers who perform tasks near them.
Because electricity is inherently dangerous, workers must be aware of the hazards they face and the steps they can take to ensure their own safety. While electricians and lineworkers may be familiar with the dangers and the best ways to avoid problems, other workers who may encounter power lines are generally not as well-trained. That can include workers such as tree trimmers, farm workers, and construction workers, as well as others who use equipment that may come in contact with lines.
This article will explore the hazards and discuss basic safety procedures. It’s important to remember that no two sites and situations are exactly the same, and this discussion cannot take the place of training or a seasoned safety professional’s review of your worksite.
Hazards of power lines
From the wires feeding your home’s panel current to high-voltage transmission lines, every system that uses electricity has the potential to injure people and damage objects. We may not think twice about changing light bulbs, but under certain sets of circumstances, even that simple act can create a risk for fatal electrocution.
There are four types of electricity-related injuries, including electrocution, electric shock, burns, and falls resulting from shocks or other situations. While most of us think in terms of direct contract with electricity as the biggest danger, other situations can be just as deadly.
When electricity travels through gases to reach a ground, we refer to its movement as an “arc.” In a controlled situation, such as during arc welding, that can be useful. But electrical arcs can also be extremely dangerous. If a worker is grounded, an arc may travel though his or her body to connect with the ground. Even if a worker doesn’t come in direct contact with the arc’s electricity, the arc flash can be so intense that it can blind or burn. The most intense kinds of arcs, which are referred to as arc blasts, can knock workers down and cause internal injuries. Arcs can also cause burns to the skin and will ignite flammable clothing and other materials.
Arcs can startle workers, and smaller electric shocks can cause involuntary muscle contractions. causing workers who are on scaffolds, ladders, or other aerial platforms to fall.
Many electrocutions result from equipment contacting power lines. Cranes, booms, and other equipment that extends into the air are involved most often. However, equipment being carried by workers — such as aluminum ladders, paint equipment with extensions, and pieces of building materials — can also hit live lines, creating a path through the workers’ bodies.
The first step in preventing injuries from power lines is locating and identifying potential hazards. Looking up is an obvious step that many workers forget. A glance around the worksite is the quick way to locate overhead lines. Of course, the potential danger doesn’t end there, because many lines are buried underground. Contact a utility locator service to identify and mark those lines if the task involves any excavating. You’ll also need to determine safe locations for equipment and materials.
Notify the utility or other owners of the lines and tell them about the work you’re planning to perform, how long it will take, and what type of equipment is involved. In most cases, the safest approach is to ask the utility to de-energize the lines while the work is being performed. If that’s not possible, the utility may be able to install temporary protective barriers or insulation to limit the possibility that your equipment will contact the lines. If the lines will remain energized while you’re working near them, ask about the voltage that is being carried.
Always assume that all overhead lines are energized until the utility or an electrician verifies otherwise. Any line that is not energized must be properly grounded before work may be performed in the immediate area.
Remember that engineering the hazard out of the task is often the safest course of action. You may be able to use an alternate approach or different equipment to reduce the risk to workers from possible contact with power lines.
The safe work distance depends on the voltage, with the absolute minimum normally being 10 feet from the lines. The higher the voltage, the greater the distance you’ll need between the lines and the workers. A commonly used formula calls for 10 feet for all lines carrying up to 50 kilovolts (50,000 volts), with an additional 0.4 inch of distance for every additional 1,000 volts. In other words, a 72-kilovolt line would require a minimum safe distance of 10 feet, 9 inches, while a 345-kv line calls for a minimum of about 20 feet.
Workers who will use long tools or carry long objects near power lines need to be briefed on the potential risk. If such work must be conducted in an area that’s closer than the minimum safe distance, designate an employee to watch the work activities and alert employees to potentially dangerous situations. In addition, insulated tools may be available to reduce the risk.
Ladders are common on worksites, and many accidents occur when a ladder comes in contact with power lines. For that reason, anytime work is being performed in close proximity to power lines, crews should use ladders made of wood or other non-conductive materials.
All workers should be aware of and use appropriate personal protective equipment, such as insulated boots and gloves to reduce the risk of electrocution, and face masks when arc flash is a potential hazard. Workers should also be familiar with two important safety rules: never touch or approach fallen power lines, and never touch or grab another worker who is receiving an electrical shock. A worker who tries to do so may become part of the electric circuit and sustain injuries of his own (or even death).
When using cranes, boom trucks, dump trucks, concrete pumpers, or other equipment capable of extending vertically or horizontally, be sure to maintain safe minimum distances and use any available insulated barriers. Once again, the safest course of action is to de-energize and ground any lines in the area.
Most power line accidents involving dump trucks happen when the truck bed has been raised, so be sure that dump truck operators are aware of the locations of power lines through signage, flags on the lines, and direct instructions from supervisors. Do not allow dump trucks to move forward or backward when the bed is raised if power lines are nearby.
Finally, if equipment must be used near live lines, designate an employee to monitor distances between the power lines and the equipment. Because it can be difficult to estimate those distances, it is important that the worker focus solely on this task, rather than try to balance multiple responsibilities.
Treat power lines with the respect they deserve, and you’ll minimize the chances of devastating injuries or severe damage on your worksites. Ignore them or take their presence for granted, and you could pay a high price.