Safety Doc's Safety Smarts: Electrical Safety - The Shocking Truth

Safety Doc's Safety Smarts is a monthly column offering safety managers and professionals information they can use as a safety toolbox talk or can include in written safety communications for employees.

By Bruce J. Schryver, Ph.D., CSP

It's only 120 volts, thinks the worker, as he puts his screwdriver into the junction box. There is a blue flash, smoke and an acrid smell as the sharp tip of the screwdriver cuts through insulation and short circuits the wiring. The worker jumps backwards, narrowly missing hitting a nearby lathe in operation. Electricity has just demonstrated that 120 volts can indeed be a formidable force to be reckoned with. In this instance, the worker was startled, not injured, because the screwdriver he was holding had an insulated handle. Had the voltage been higher, he might not have been so lucky.

Electricity has a way of always wanting to reach a ground through the easiest means available. If everything else is insulated and the circuit to ground is solid, the electricity will flow unimpeded through the wiring and power your tools, lights and equipment. However, if the easiest path to ground is through your body, electricity will take that route. And, that's where the danger lies.

Electricity does strange things to the human body. It contracts muscles, and frequently the person who comes into contact with a live conductor cannot release their grip. It burns, destroys tissue and muscle mass, and frequently causes ventricular fibrillation, a condition where the electrical impulses of the heart are interrupted and overpowered, so the heart will not beat properly. The muscles controlling the respiratory system may fail. In many cases, death follows shortly after electrical shock.

Two very important facts about electricity:

1. Electricity can cause death, even from low voltages. In fact, most deaths are a result of contact with ordinary 120-volt house current. Don't ever be fooled into thinking that simply because the voltage is low that you can't be injured. You may be dead wrong!
2. One-tenth of an ampere is sufficient to cause fibrillation and death. A 120-volt circuit powering a single 100-watt light uses about an ampere. So the electricity used to light a 10-watt bulb, just a little bigger than a night light, can be deadly!

Many times deaths from contact with electricity do not occur strictly from contact with live electrical conductors. They occur from a secondary motion or reaction to the shock. For instance, had the worker in our example hit the lathe, he may have had serious injuries, although he was not actually shocked by the electrical current.

Many workers are not familiar with electrical safety rules. Unfortunately, that can lead to serious injury or death. One of the common misunderstandings is on the use of Ground Fault Circuit Interrupters or GFCI's. These units are designed to interrupt the flow of electricity if a ground fault is detected. A ground fault may be a broken ground wire in an electrical tool or appliance, or the wiring supplying electricity to the tool. The ground path is no longer available, so the electricity is looking for the "path of least resistance" to ground. And, that may send current down the frame of the tool and through your body. Perspiration makes the body an even better conductor, as do damp conditions.

Never bypass a GFCI for any reason. If you have a defective GFCI, replace it. If the job site has a common GFCI line for the workers, use it. If you are using a portable generator, always use a GFCI. Generators are just as likely to electrocute you as any other electrical source. Electricity doesn't care whether it comes through the distribution system wires of a utility, or through a portable generator. All it wants to do is go to ground and complete the circuit. Don't make yourself part of its path to ground.

What's Your Electrical Safety IQ?

1. Larry's toaster never seems to pop up the toast without burning. Larry sticks his knife into the toaster to pull out the burning toast. Can Larry be electrocuted?
2. Wrapping damaged or frayed insulation on an extension cord is okay as long as you use electrical tape. True or false?
3. Only non-conductive ladders such as wood or fiberglass should be used when working on electrical equipment. True or false?
4. Even though someone else says the electrical line is "dead," I should always check the switches and test the line before commencing work. True or false?
5. An electrical plug will not fit in the outlet because it's a three prong, and the outlet only accepts two prong plugs. Do you cut off the extra prong, use an adapter, or change the outlet?
6. You are working outside in a damp location. You have a drill, a good extension cord, an assortment of drill bits for the job and safety glasses. What else should you have?
7. You don't have a GFCI on the line. You are drilling holes in a metal plate with a corded drill, and you feel a tingling sensation. What should you do?

1. That toaster pulls over 1000 watts, and about 10 amperes. That's 100 times the current that will cause fibrillation. Larry could be "toast!" The answer is a definite "yes," Larry could be electrocuted.
2. False. Cords should be replaced rather than repaired. The electrical tape will not replace the cord's insulation. Damaged cords are accidents waiting to happen.
3. True. Aluminum ladders are conductors of electricity and are dangerous around energized electrical equipment.
4. True. Absolutely! Never depend upon anyone else to be sure the power is off. Lockout and tagout all electrical work, every time!
5. Have a qualified electrician change the outlet. Never cut off the grounding prong or use an adapter. Neither gives you positive grounding.
6. You should have a portable Ground Fault Circuit Interrupter (GFCI) unless the plug where you are connecting the cord is already GFCI-protected. Be sure, and if you can't confirm the presence of a GFCI, use a portable one anyway.
7. Stop immediately! Your drill, if not double insulated, may have developed a ground fault. Have it checked by an electrician to be sure it's working properly.

How many did you get right? Working safely with electricity is very important. Electricity is very unforgiving, and one mistake can result in serious injury, or even be fatal. Give electricity the respect it deserves!

About the author: Bruce J. Schryver, Ph.D., CSP, CHCM, CHMM, CPSM, CHSP, has been in the safety and health field for over 30 years. He started out as a first responder with a rescue unit, was with the Coast Guard, and law enforcement before embarking on a career in occupational safety and health. He has been employed as director of safety for a 1700 employee steel fabricator, and as a loss control consultant, regional loss control manager and national loss control coordinator for a group of insurance companies. He joined the ICW Group in 1985 and is now vice president of loss control services as well as vice president of Municipal & Law Enforcement Services. Schryver holds a bachelors degree in occupational safety and health and a Masters and Doctorate in safety management. He is a Certified Safety Professional (CSP), a Certified Hazard Control Manager (CHCM), Certified Hazardous Materials Manager (CHMM), Certified Products Safety Manager (CPSM) and a Certified Healthcare Safety Professional (CHSP). In addition to being a Professional Member of the American Society of Safety Engineers, he is a member of the Society of Fire Protection Engineers, National Safety Management Society and the California Conference of Arson Investigators. He is an instructor for the IIA Associate in Loss Control Management classes.

Subscribe to our free e-mail newsletter.

Click for a free Buyer's Guide listing.