(c) 0.050 amperes. Pain, possible fainting, exhaustion, mechanical
injury. Heart and respiratory function may continue.
(d) 0.100-3.0 amperes. Ventricular fibrillation.
(2) Some important factors that determine whether or not an electrical shock
is fatal are the person involved and his state of health, the area of the body involved,
and the length of time the shock is received.
(a) Electrical shock can have both psychological and physiological
effects. In the case of elderly people or those in poor health, an electrical shock that
would otherwise be minor could trigger a fatal heart attack. It is generally recognized
that a current of 0.001 amperes through the body will give a tingling sensation.
Although not sufficient to kill, it is sufficient to bring about a psychological reaction that
could result in death. Consequently, to be safe--it is best to prevent any type of
(b) The area of the body involved in an electrical shock is very
important. If a current of 0.05 amperes flows from the hand to the elbow, the effects
would probably be minor. On the other hand, if the same amount of current would flow
from hand-to-hand through the heart, it could be fatal.
(c) The length of time the shock is received is a very important factor.
If the shock is of short duration, the chances of survival are much better.
b. Effects of Resistance. Because current determines the severity of an
electrical shock, the goal of electrical protection must be to reduce electrical currents
through the body to an absolute minimum. The voltage in an electrical circuit does not
change simply because a person decides to be careless and touch it. According to
Ohm's law, the only current-limiting factor over which you have control is the resistance.
Electrical protection, therefore, is based on the premise of reducing electrical currents
through the body by offering a very high resistance to current flow.
(1) Let's assume that an individual touching the 110-volt line has dry hands
and represents a resistance of 22,000 ohms. According to Ohm's law, the current
would be 0.005 amperes. This would probably cause an unpleasant tingle, and the
individual would quickly withdraw his hands from the circuit.
(2) In the same situation, if the individual had wet hands, the body
resistance would decrease to 5,500 ohms. As a result, the current would increase to
0.02 amperes, which would probably be enough to make it difficult for the victim to free
himself from the circuit.
(3) If, however, the individual touches one side of the circuit with rubber
gloves, the high resistance of the rubber increases the total body resistance and, as a
result, the body current is too low to be detected by the individual.