Many employees are exposed to electricity daily in their work environments. It can be very safe as long as employees understand the basic principles of electricity and the safety precautions that must be taken when working around energized lines and equipment. According to NIOSH an average of 411 deaths occurs each year in the workplace due to contact with electrical energy. Electrocutions are the fifth leading cause of death, accounting for 7% of all workplace fatalities.
The number of people who believe that normal household current is not lethal or that overhead power lines are insulated and do not pose a hazard is alarming. This presentation discusses the basic principles of high-voltage and includes high-voltage work rules for both electric utility employees and others who may work near energized high-voltage lines to include clothing and PPE requirements and electrical protective equipment and grounding requirements.
Electricity is always looking to travel to the ground and it is constantly seeking the shortest path to ground. It will take the path of least resistance and it may take multiple least resistant paths to ground. Electric shock occurs when the path of least resistance is through the human body. The human body is composed of approximately 80% water and water is a great conductor of electricity.
Electricity travels at the speed of light (186,000 miles per second) and is three to four times hotter than a burning building (6,000 to 8,000 degrees). Electric arc temperatures can melt steel. When a short circuit occurs or current flow is interrupted, an arc is often created. If the current involved is great enough, these arcs can cause injury or can start a fire. Fires can also be caused by overheating equipment or by conductors carrying too much current. Extremely high-energy arcs can damage equipment causing fragmented metal to fly in all directions. In explosive or combustible atmospheres, even low-energy arcs can cause violent explosions
Overhead power lines have no insulation except being isolated in air. The air serves as an insulator because air has fewer free electrons than the wire conductor. For this reason overhead bare metal conductor is installed on insulators made of porcelain, glass or synthetic polymer materials.
Voltages over 600 volts are considered high-voltage. High-voltage electric shock is very powerful and normally pushes (or blows) the person away from the source due to the high-voltage pressure. It can rupture human skin, greatly reducing the resistance of the human body, allowing more current to flow, causing greater damage to internal organs.
Electrical injuries consist of four main types:
Electrocution (fatal)
Electric Shock
Electrical Burns
Falls caused as a result of contact with electrical energy.
Electrical injuries may occur in various ways:
Direct contact with electrical energy
Injuries that occur when electricity arcs to a victim
Flash burns generated by an electrical arc
Flame burns from the ignition of clothing or other combustible material.
