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District 8 - Coal Mine Safety and Health
Info-Grams and Close Call Accidents


Info-Grams
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Department of Labor
Mine Safety and Health Administration

Accident Info-Gram
FEBRUARY 2004

Two Electric Shock Instances

At least two separate instances of electrical shock have occurred in District 8 during the last month. These two electrical shocks resulted while contacting or handling a damaged energized trailing cable or power cable. As a result of these electrical shocks, District 8 wants to remind all mine personnel of the small amount of current required to cause serious injury or death.

Severity of electrical shock is determined by three factors:

    • Path - entering the body and exiting the body
    • Amount of current or energy flowing in the body
    • Duration of exposure - degree of injury also depends on the duration and frequency of the current.
The following chart gives the effects on the human body when exposed to electrical currents:

60 Hz AC Current Response
0.5 - 3 mA Start to feel the energy, tingling sensation
3 - 10 mA Experience pain, muscle contraction
10 - 40 mA Grip paralysis threshold (brain says let go; but physically cannot do so)
30 - 75 mA Respiratory systems shuts down
100 - 200 mA Experience heart fibrillation
200 - 500mA Tissue and organs burn
(A 110-volt, 100 watt light bulb pulls approximately 900 mA)

Accident victims can incur the following injuries from electrical shock:
  • Low-voltage contact wounds
  • High-voltage contact wounds from entry and exit of electrical current
  • Burns
  • Respiratory difficulties (the tongue may swell and obstruct the airway; or vaporized metal or heated air may have been inhaled)
  • Infectious complications
  • Injury to bone through falls, heat necrosis (death of tissue) and muscle contraction (shoulder joint injuries and fracture of bones in the neck are common injuries caused by muscle contraction).
  • Injury to the heart such as ventricular fibrillation, cardiac arrest or stoppage
  • Internal and organ injuries
  • Neurological (nerve) injury
  • Injury to the eyes (cataracts from electrical injury have occurred up to three years after the accident)
BEST PRACTICES
  • Wear work gloves or electrically rated gloves to provide better protection from electrical shock while handling or contacting electrical cables
  • Ensure that trailing cables and power cables are hung and/or protected from damage
  • Ensure that trailing cables and power cables are fully insulated

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This file was last updated on 3/1/2004

This information was provided by concerned miners in an effort to eliminate accidents. Accident or "close call" information within District 8 may be shared by contacting the MSHA office at (812) 882-7617.