milliampere (milliamp or mA) 1/1,000 of an ampere
shocking current electrical current that passes through a part of the body
You will be hurt more if you can't let go of a tool giving a shock.
The longer the shock the greater the injury.
1 milliamp Just a faint tingle.
5 milliamps Slight shock felt. Disturbing, but not painful. Most people can "let go." However,
strong involuntary movements can cause injuries.
6-25 milliamps (women)†Painful shock. Muscular control is lost. This is the range where "freezing
9-30 milliamps (men) currents" start. It may not be possible to "let go."
50-150 milliamps Extremely painful shock, respiratory arrest (breathing stops), severe muscle
contractions. Flexor muscles may cause holding on; extensor muscles may
cause intense pushing away. Death is possible.
1,000-4,300 milliamps (1-4.3 amps) Ventricular fibrillation (heart pumping action not rhythmic) occurs. Muscles
contract; nerve damage occurs. Death is likely.
10,000 milliamps Cardiac arrest and severe burns occur. Death is probable.
(10 amps)
15,000 milliamps Lowest overcurrent at which a typical fuse or circuit breaker opens a circuit!
(15 amps)
Severity of shock depends on voltage, amperage, and resist- ance
resistance a material's ability to decrease or stop electrical current
ohm unit of measurement for electrical resistance
Lower resistance causes greater currents.
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, NABCEP PV Installer Exam
NEC—National Electrical Code a comprehensive listing of practices to protect workers and equipment from
electrical hazards such as fire and electrocution
arc-blast explosive release of molten material from equipment caused by high-amperage
arcs
arcing the luminous electrical dis- charge (bright, electrical sparking) through the air that
occurs when high voltages exist across a gap between conductors
There are three primary hazards associated with an arc- (1) Arcing gives off thermal radiation (heat) and intense light, which can cause
blast. burns. (2) A high-voltage arc can produce a considerable pressure wave blast. (3)
A high-voltage arc can also cause many of the copper and alu-minum
components in electrical equipment to melt
Class A fire extinguisher (think: Ashes) = paper, wood, etc.
Class B fire extinguisher (think: Barrel) = flammable liquids
Class C fire extinguisher (think: Circuits) = electrical fires
Burns are the most common injury caused by electricity. electrical burns, arc burns, and thermal contact burns.
The three types of burns are
OSHA Occupational Safety and Health Administration—the Federal agency in the U.S.
Department of Labor that establishes and enforces workplace safety and health
regulations
Electrical Fires Electricity is one of the most common causes of fires and thermal burns in homes
and workplaces
Thermal burns may result if an explosion occurs when electricity ignites an explosive mixture of material in
the air.
Electrical burns can result when a person touches electrical wiring or equipment that is used or maintained
improperly
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