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 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
that can kill!
-
Not being able to "let go" due to muscle contractions
increases the duration of shock. A current of 100 mA for 3 seconds is
equivalent to 900 mA for 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
- Below 600 volts, dry skin is 100× more resistive
- Contact area
- A finger contact is higher resistance than a
whole hand.
- A finger contact is higher resistance than a
whole hand.
- Pressure of contact
- Greater pressure decreases resistance, increases
the likely burn.
- Greater pressure decreases resistance, increases
the likely burn.
- Duration of contact
- The longer the contact, the more likely the burn.
- The longer the contact, the more likely the burn.
