You’ll be Shocked!
The Anatomy of Electrical
Failures and Accidents
Jesse M. Cohen
Ron Kilgore
What We’ll Cover
The Hazards of Working With Electricity
Electric shock
Arc flash injuries
Demonstration of electric arc
How Electricity Affects the Human Body
Electrical burns
Internal damage to the heart, muscles, and brain
Cardiac arrest
Muscle, nerve, and tissue destruction
Thermal burns
Falls from heights due to shock
Causes of electrical accidents
Work performed on energized equipment
Arc Flash
Failure to use PPE (Personal Protective Equipment)
Demonstration of PPE and resistance to heat and flame
Electrical Safety in the Workplace Under NFPA 70E
Third Party Liability in Electrical Accident Claims
Equipment manufacturers
Contractors
Property owners
The Hazards of
Working With
Electricity
How Electricity Affects the Body
• Electric current is conducted through a
material.
• Any resistance results in a dissipation of
energy, usually in the form of heat.
• Electric current makes tissue heat up.
• If the amount of heat generated is sufficient,
the tissue may be burnt.
• Electricity has the ability to burn tissue well
beneath the skin of a victim, even burning
internal organs.
How Electricity Affects the Body
•
•
•
•
Electric current also affects the nervous system.
Nerve cells communicate to each other via electrical
signals.
If electric current is conducted through the body, its effect
will be to override the tiny electrical impulses normally
generated by the nerve cells, overloading the nervous
system.
Muscles triggered by an external current will then
involuntarily contract.
Thresholds of Electrical Injury
Electric current (contact for 1s)
Effect
Below 1 mA
Not perceptible
1 mA
Threshold of feeling, tingling
5 mA
Slight shock. Not painful. Average
individual can let go. Involuntary
reaction can lead to indirect injuries
6-25 mA (women)
Painful shocks. Loss of muscle control
9 to 30 mA (men)
Freezing current, "can't let go". The
person may be thrown away from the
power source. Individual cannot let go.
Strong involuntary reaction can lead to
involuntary injuries
50 to 150 mA
Extreme pain. Respiratory arrest.
Muscles reactions. Possible Death.
1 to 4.3 A
Fibrillation of the heart. Muscular
contraction and nerve damage occur.
Likely death.
10 A
Cardiac arrest, severe burns. Death is
probable
Causes of Electrical
Accidents
Causes of Electrical Accidents
Working on
energized
equipment
Causes of Electrical Accidents
Arc Flash
Arc Flash Boundaries
Personal Protective Equipment
Falls
• Accident: 200081966 - Employee Dies
After Electric Shock Causes Fall From
Ladder
• On April 22, 2004, Employee #1 was
on a ladder disconnecting electrical
equipment inside an energized, 480volt, disconnect switch. He was
cutting a wire inside the switch when
he received an electric shock that
caused him to fall off the ladder onto
the concrete. Employee #1 died of
injuries sustained in the fall.
Electrical Safety in the
Workplace
Safety in the Workplace
Third Party Liability
Third Party Liability
Equipment Manufacturers
Contractors
Property Owners
Property Owners
Property Owners
Property Owners
Property Owners