Electrical Safety

How much current does it take to kill?  There are many instances where persons have survived 30,000 and 40,000 volts while many other cases record death due to contact with less than 120 volts.  There is no simple answer.  One person may escape injury from higher voltages due to dry skin or other factors that prevent efficient contact.  A lower voltage may kill another person when the circuit is easily completed due to contact with damp skin while the victim stands on a wet deck.  High voltage shocks are usually serious, if not fatal, due to destruction of tissues and nerve centers.  Fortunately, most people are aware of the danger of high voltage and stay clear of it.  Even so, misuse of electricity causes over 1,000 deaths each year.

Other than the organic damage connected with electric shock, a serious hazard resulting from a minor shock is the involuntary muscular reaction of the victim.  They may jump, jerk, stumble or fall with the result that they may sustain even more serious secondary injuries or injure others.

Under some conditions the amount of current that passes through your body may cause only a slight tingle, but the next encounter may be your last.  There is no way to tell in advance whether the conditions of your body are right to pass the necessary amount of electric current to kill you.  The total effect of electric shock is not dependent on voltage alone but on the conditions surrounding it; such as the following:

The effect of electric current on the body varies.  As low as five milliamperes can cause slight shock. A painful shock and loss of muscular control can occur at 6-25 milliamperes for women and at 9-30 milliamperes for men. Strong involuntary muscle reactions can lead to other injuries.

A 50-milliampere shock causes extreme pain, respiratory arrest, severe muscular contractions and possibly death.  At 1000 milliamperes, death is likely.  The longer the exposure, the greater the risk of serious injury.  Since a common result in electrical accidents is failure of that part of the nervous system which controls breathing, many victims have been saved by prompt application of artificial respiration.  Persons engaged in electrical work should be familiar with resuscitation practices.

What should you do if someone “freezes” to a live electrical contact?  Shut off the current immediately.  If this is not possible, use boards, wood poles, or sticks of wood or any other non-conducting materials and safely push or pull the person away from the contact.  It is important to act quickly, but remember to protect yourself from electrocution or shock.  Do not place your hands directly on the victim. 

It is difficult to determine the extent of internal injuries to a victim of electrical shock.  If you or a coworker receives a shock, seek emergency medical help immediately.

How are we protected from electrical shock?  Insulation such as glass, mica, rubber or plastics help prevent shock, fire and short circuits.  To be effective, the insulation must be in good condition and suitable for the voltage and conditions such as temperature and other environmental factors like moisture, oil gasoline, corrosive fumes, or other substances that could cause the insulator to fail.

What can we do?  Before you work with electrical equipment, be sure your hands and feet are dry.  Use appropriate PPE and protective equipment. Maintain all electrical equipment in good repair. Do not use suspect equipment—consult someone who knows. Before you plug in an extension cord, a droplight, or a piece of electrical equipment, look it over closely to see that wires aren’t frayed. All extension cords must have ground wires with a polarized plug or a ground clamp. Protect the cord while it is being used.  If a cord has to run across an aisle, string it overhead if possible.  If it must run along the floor, protect it so it can’t be run over or jerked loose, or become a tripping hazard. Extension cords smaller than #12 should not be spliced. Keep electric tools and equipment properly maintained. Only qualified personnel should be allowed to work on electrical equipment. De-energize equipment and utilize Lockout/Tagout procedures before inspection or repair. Keep enclosures on electrical equipment such as switch boxes closed and secured.  When repair work is done, ensure that the cover is replaced before the unit is energized.  Ensure proper grounding is utilized.  Exercise caution when working near energized lines.