LLE Safety Zone

Electricity Reference

Electricity is a serious health and safety hazard when not handled properly

  • Fire — Electricity is the most common source of workplace fires.
  • Explosion — During an electrical arc, copper expands 67,000× as it is vaporized. Like dynamite, eye and ear damage commonly occur.
  • Shock — May cause nerve and tissue damage and possible cardiac arrest.
  • Thermal Burns — Due to contact with arc plasmas and adjacent heated materials.
  • Direct Burns — Due to conductance of muscle and organ tissues. Internal damage may not be apparent for many days.

The Shocking Facts: How electricity affects your body

  • Shock is the nerve sensation and muscle spasm caused by electric current flowing through the body.
  • Shock occurs when your body becomes part of a circuit.
  • The severity of shock is determined by three factors:
    • the amount of current flowing through your body,
    • the path the current takes through your body, and
    • the total time current flows through your body.

Effects of current on the human body

General relationship for a 60-cycle, 1-second-duration shock:

Current effects
Current Amplitude Reaction in body
1 mA Faint tingle
5 mA Not painful but disturbing
6 to 25 mA Painful shock, muscular reaction
9 to 30 mA Frozen to conductor
50 to 150 mA Extreme pain, respiratory arrest, contractions
1 to 4 A Ventricular fibrillation
10 A Cardiac arrest, severe burns

Notice that the difference of <100 milliamperes (ma) exists between a current that is disturbing, but not painful, and one can kill! not being able to "let go" due muscle contractions increases the duration of shock. 100 ma for 3 seconds equivalent 900 0.03 seconds, in effect causing ventricular fibrillation.

The dangers of high-voltage electricity:

  • Hearing loss
  • Eye damage
  • Cuts and bruises
  • Thermal burns
  • Direct burns
  • Broken bones
  • Cardiac arrest
  • Death

Variables that contribute to your skin’s resistance to electricity:

  • Amount of moisture on your skin
    • Below 600 volts, dry skin is 100× more resistive
  • Contact area
    • A finger contact is higher resistance than a whole hand.
  • Pressure of contact
    • Greater pressure decreases resistance, increases the likely burn.
  • Duration of contact
    • The longer the contact, the more likely the burn.