4.1: Definition

An electrical hazard can be defined as a serious workplace hazard that exposes workers to the following: burns, electrocution, shock, arc flash/arc blast, fire, and explosions. A burn is the most common shock-related injury. Burns from electricity are one of three types: electrical, arc/flash or thermal contact. Electrocution is a fatal injury that occurs when a person is exposed to a lethal amount of electrical energy. Shock results when the body becomes part of the electrical circuit; current enters the body at one point and leaves at another. Electrical shock is defined as a reflex response to the passage of electric current through the body. An arc flash is the sudden release of electrical energy through the air when a high-voltage gap exists and there is a breakdown between conductors. An arc flash gives off thermal radiation (heat) and bright, intense light that can cause burns. Temperatures have been recorded as high as 35,000 °F. High-voltage arcs can also produce considerable pressure waves by rapidly heating the air and creating a blast. Most electrical distribution fires result from problems with "fixed wiring" such as faulty electrical outlets and old wiring. Problems with cords (such as extension and appliance cords), plugs, receptacles, and switches also cause electrical fires. An explosion can occur when electricity ignites an explosive mixture of material in the air. Note that although a) electricity is the source of these hazards, and b) all of these hazards are of equal importance, for this focus four module, this lesson focuses on electrocution hazards.

Examples

The following are examples of electrocutions that have occurred in the construction industry:
■ Two workers were moving an aluminum ladder. One of them was electrocuted when the ladder came in contact with overhead power lines.
■ A worker was raising a mast on a water well drilling truck when the mast came in contact with high voltage overhead lines, electrocuting the worker.
■ Worker was electrocuted when the boom of a rotary drilling truck contacted an overhead power line. The victim and another worker had just finished drilling a water well at a residential property. The victim moved the truck away from the well. The victim was standing at the controls, lowering the boom and was thrown several feet away from the truck.
■ Worker was fatally injured when he was electrocuted and fell to the concrete floor while working from an 8' fiberglass step ladder. Worker was changing an energized ballast on a two bulb florescent light fixture, located approximately 11'6" off the ground.
■ The worker was electrocuted while connecting a replacement electrical service box to the electrical service drop to the building.

Statistics

Data from the U.S. Bureau of Labor Statistics (BLS) show that electrocution was the fourth leading cause of death in construction in 2005, after falls to a lower level, transportation injuries, and being struck by objects and equipment. Electrocutions caused 9% of 1,243 construction worker deaths, but accounted for less than 1% of reported recordable nonfatal injuries in 2005. For 2003-2005, the death rate from electrocutions for the construction industry was 1.1 per 100,000 full-time workers, for was an average of 121 electrocutions per year. The highest rates of death from electrocution were among electrical power installers and repairers and earth drillers.