It’s good to have a certain amount of fear when working as an electrical contractor. Having no fear can lead to being careless and carelessness can lead to serious injury or death. A good electrician will shut off a power source, test to make sure that the power is off and then STILL treat the wires as if they’re hot. Too many electricians have been hurt or killed because they were careless or rushed while on the job.
Both AC and DC electrical lines can cause a range of injuries and levels of shock. The severity of the shock depends on the path of the current through the body, the amount of current flowing through it and the length of time the body remains in the circuit.
A voltage as low as 50 volts applied between two parts of the human body causes a current to flow that can block the electrical signals between the brain and the muscles. The exact effect is dependent upon a large number of things including the size of the voltage, which parts of the body are involved, how damp the person is and the length of time the current flows.
At high voltages, you don’t even have to make direct contact with charged equipment to be shocked because an electric field surrounds all charged devices. Bringing a conducting object – such as a human body – into that field can intensify the field enough for an arc to jump from the equipment to the earth through that person. Even solid materials such as rubber, which is an excellent insulator at low voltages, is subject to electrical failure if subjected to a high enough field.
In the U.S., the Occupational Safety and Health Administration (OSHA) establishes safety and clearance guidelines for all types of electrical workers. According to OSHA, a construction worker exposed to 1 mA of electrical current might feel only a tingling sensation. Anywhere from 6 (mA) to 16 (mA) is referred to the “let go” zone, when a person still has the ability to remove himself or herself from the source of the electricity. Beyond 17 (mA), the victim will be unable to let go and damage to the respiratory system and other internal organs is likely to begin. Beyond that point, death is possible. Here are several very good reasons to never work with live electricity.
Electrical shocks can be as harmless as touching a doorknob after walking on carpet or deadly as being caught in an arc flash. However, enough static electricity can cause a fire or explosion when it builds up in or near an explosive atmosphere (such as in a paint spray booth).
Electrical burns are the most common shock-related, nonfatal injury. They occur when a worker contacts energized electrical wiring or equipment, occurring most often on the hands and feet. When an electrical current passes through the human body it heats the tissue along the length of the current flow. Deep burns may require major surgery and can be permanently disabling. Burns are more common with higher voltages but often occur from domestic electricity supplies if the current flows for more than a few milliseconds.
Loss of Muscle Control
Workers who receive an electric shock often get painful muscle spasms that can be strong enough to break bones or dislocate joints. This loss of muscle control often means the person cannot let go or break the circuit. The electrician may fall if they are working at height or be thrown into nearby machinery and structures.
These burns are caused by contact with objects thrown during the blast associated with an electric arc. The blast comes from the pressure developed by the near instantaneous heating of the air surrounding the arc and from the expansion of the metal as it is vaporized. The pressure wave can be great enough to hurl people, switchgear and cabinets considerable distances. It can stop your heart, impale you with shrapnel, blow off limbs, cause deafness, and cause you to inhale vaporized metal. The hurling of molten metal droplets can also cause thermal contact burns and associated damage.
Electrical workers who survive electrocution rarely regain their former quality of life. Despite immediate medical attention, electrocution can leave a person with brain injuries, nerve damage, heart problems, permanent organ damage, vision, speaking and hearing defects and bodily disfigurement from serious burns.
Death from being electrocuted usually results from fatal effects on the heart, severe external and/or internal burns or other organ damage.
There is no iron-clad rule as to what level of voltage will kill or seriously injure a person because of all the variables involved on every job, but playing fast and loose with live electricity is the best way to find out in the most personal way possible. If you do find it absolutely necessary to work with live electricity, it’s a good idea to have a friend nearby who is trained in CPR.