Understanding and Preventing Electrocution When Using Aerial Devices and Digger Derricks

Power lineman working on power lines

Lineworkers face the ever-present danger of electrocution as they work on or near electrical components. It is important and absolutely necessary to follow your employer's work rules, ANSI NESC requirements, OSHA regulations and the equipment manufacturer's information to reduce the chance of serious injury or death.

Electrocution occurs when a person’s body is a path for electric current. The body becomes a path by touching, or getting too close to, two objects at different potential (voltage). The voltage difference causes the current flow. You do not have to touch an object to be a path. The electric current can jump through the air if the distance, voltage, and weather conditions qualify.

The path is not always from a hot wire in your hand to the ground under your feet. The following list gives examples of possible hazards and is not complete. There are many possible combinations where a person’s body can become a path for electric current.

Some examples include:

From a phase or hot wire, through you, to a pole or any of its hardware
From a phase wire, through you, to a neutral or static wire
From a phase wire, through you, to a different phase wire
From a lineman, working on one potential, through you, working on a different potential
From an end of a ground wire, through you, to the other end of a ground wire, when splicing.
From a ground wire, you are holding, through you, to the controls you are operating when any part of the boom tip touches an energized phase
From a phase wire in contact with, or too close to, a non-insulated portion of a boom, through you, while standing on the ground touching the truck or attached trailer
From one foot, through you, to the other foot if near an energized vehicle or a live wire lying on the ground. Note: this is known as step potential
From a pole through you to the ground you are standing on. When the pole you are helping to set or remove comes in contact with, or too close to, an energized phase and you are touching the pole with an unprotected part of your body.

Whenever any two parts of your body are at a different potential, current will flow through your body between the two points that make contact. There is no warning when electricity decides the body is a suitable path. You cannot see electricity before it chooses its path or outrun electricity once it decides on its path.

Bucket trucks and digger derricks with insulated booms prevent current flow from the boom tip to ground through the boom only, provided no other conductive components cross the insulating span (such as ropes) and the insulated section is clean, dry, tested and certified for the voltage. Follow all personal protective equipment (PPE), coverup, and approach distance requirements every time you work near electric power sources. You cannot always foretell when there will be a sudden dangerous change.

To read more about what ‘insulated’ really means, click here to read our Utility Pros article on the subject.