Electrical safety is a topic worth discussing repeatedly. Both government and private organizations cover it. The Occupational Safety and Health Administration (OSHA) has developed regulations addressing electrical hazards. Organizations, such as the Institute of Electrical and Electronics Engineers (IEEE) and the National Fire Protection Association (NFPA), have created consensus standards to address electrical issues. In particular, NFPA developed 70E—the Standard for Electrical Safety in the Workplace. While a large portion of this standard appears to apply to electricians’ work only, all employees on the work site can benefit from an awareness of the hazards it addresses and the precautions it offers.
The first benefit of NFPA 70E is that it has brought attention to the fact that electrical mishaps can present many hazards. The one we are most familiar with is shock. However, this is not always addressed completely. In addition to shock, there are the hazards associated with an arc flash. An arc flash (or arc blast) is a type of electrical explosion that results when a short circuit occurs through air. When an object offering a path to ground or a lower voltage comes near an exposed live circuit or part, the current will flash over. Of course, there also is the fire hazard associated with electricity.
Looking closer at the shock hazard, it’s important to understand a little more about the body and electricity. Your body uses electrical impulses to move your muscles. When an electrical current passes through any object, it will generate heat. Looking at these two factors together helps explain what happens when you get a shock. The external source of electricity during a shock will overpower the electrical impulses of your nerves. This external electrical source can cause muscles to contract so violently that bones could break. If this electrical source passes through the heart, it could take over your heart muscle, causing it to stop beating. The sites where the external current enters and exits the body will be burned from the heat generated from the movement of the current. It can also burn anything in its path between these two points, including nerves, blood vessels and internal organs.
When an arc flash occurs, energy is released into the environment in the form of light, noise, heat and pressure. The temperatures associated with an arc flash can reach as high as 35,000°F. The high-intensity flash that is released can cause permanent damage to a worker’s eyesight. Pressures that an arc flash releases can reach thousands of pounds per square foot. The pressure alone can be damaging, but when combined with the molten metal formed from the released heat, shrapnel can shoot out at speeds in excess of 700 mph. The noise that is created can exceed 160 decibels, a level that would cause permanent hearing damage.
The last and worst danger from electricity is fire. The extreme heat generated by the flash has been seen to ignite almost any substance with which it comes into contact. However, even without an arc flash, the heat generated when electrical current is forced through a high-resistance object can be enough to cause a fire. This can be best illustrated by considering the amount of heat generated when a homeowner overloads an extension cord and then places the cord under a carpet, trapping the heat. This captured heat will melt the insulation on the cord and ignite the carpet.
With the knowledge of many of the possible hazards associated with electricity, it is important that you recognize the potential for electrical danger. This can be accomplished by simply observing warning signs, which includes experiencing a tingling sensation when you touch an electrical appliance or other metal object. This sign of a very mild shock can indicate a more serious problem exists with a tool or piece of equipment. That problem needs to be addressed before a more dangerous shock incident occurs.
An easy way to prevent anyone else from being injured is to tag and remove the source of the shock from service. Another sign of a potential electrical issue is a persistent burning smell coming from an appliance, tool, room or area. This odor can be indicative that the appliance or piece of equipment is overheating or malfunctioning. The offending appliance or piece of equipment should be unplugged and tagged and removed from service until it can be repaired or, if necessary, replaced. Listening to the precautions offered in on-the-job safety talks on electricity and by observing the boundaries and behaviors established for qualified and unqualified workers can help to keep all employees safe and able to head home to their families.
KELLY is a safety and health specialist with Intec, a safety consulting, training and publishing firm that offers on-site assistance and produces manuals, training videos and software for contractors. She can be reached at 800.745.4818 and firstname.lastname@example.org. Joe O’Connor edited this article.