The numbers (volts/ma) don't sound that bad compared to what I have been shocked with. How did it feel? Worst for me was a GMC Jimmy's coil (something like 60,000v, 0.000001a) ouch, couldn't sleep for 36 hours.
I think he will be ok, his show a glass/plastic globe to protect from that risk.
Do I put you ignore NOW or Later? Are we a babysitting service now? I thought 30 year olds were grown adults.
Thanks StardustSailor........
Clifford D. Ferris
22.1.1 Introduction
Human tissues, such as the skin and the muscles, as well as blood and other body fluids are classified as
electrolytes. Consequently, they are electrical conductors that may be characterized in terms of ohmic
resistances. Electric potential differences applied across human tissues, or at two locations on the external
skin surface, generate response currents.
Electric shock can be divided into two classes: microshock and macroshock. Microshock describes an
internal shock that may occur as a consequence of certain medical diagnostic procedures (such as cardiac
catheterization) or surgical procedures inwhichelectrically operated sensors are introducedintothehuman
body. Electric current levels associated with microshock range from 10 to 100 μA. This phenomenon is
specific to medical procedures and will not be addressed further in this chapter.
Macroshock, or simply electric shock, describes simultaneous contact between the body surface and
two electrical conductors at different potentials, and the physiological consequences of this contact. The
two conductors may be a hot conductor and ground, or two hot conductors, such as two of the phase wires
in a three-phase power distribution system.
The severity of the consequences of electric shock depends on a variety of factors. The physiological
effects of electrical shock are not produced by electric potential (voltage) per se, but rather by the electric
current that is driven by the potential difference that is applied externally to the body surface.Consequently,
the combined effective electrical resistance of the body volume involved and the intimacy (surface area
and pressure) of the skin-conductor contact have a major effect on the severity of electric shock. The
paths through the body that the shock currents take determine the potential seriousness of the shock.
Generally speaking, current paths that do not include the head or main trunk of the body are not fatal,
although permanent damage may be produced in the formof scars, nerve ormuscle impairment resulting
in partially or fully paralyzed limbs, and loss of limbs. Electric shock currents that pass through the chest
in the region of the heart or lungs may cause death, either by direct effect on the heart, or by paralysis
of the nerves that control the breathing diaphragm. Severe electric shocks to the head may cause death
or permanent brain damage. As illustrated in Fig. 22.1, the two most dangerous current paths are from
hand-to-hand, and hand-to-foot (especially left hand to left foot) since the current passes through the
chest and potentially through the heart.
Response to electric shock is subjective to some extent, with both physiological and psychological
components. The condition of the skin surfaces that come into contact with the electrical conductors is
an important factor. For example, if an adult grasps the probes of a digital ohmmeter tightly between the
thumb and forefinger of each hand, the resistance displayed will vary widely among individuals.
Those
individuals who use their hands in activities that build up callouses may produce resistance readings on
the order of 1 or 2 M when the hands are dry, and perhaps 100 k when the hands are wet. Other
individuals with soft and pliant skin may register 5–10 k with dry hands and significantly lower values
when the hands are moist or wet. If the ohmmeter is powered by a 9-V battery, the maximum possible
current sustained in the1-Mcase is 9μA, whereas it is 0.9mAwhen the resistance is 10 k(
a thousandfold
increase).
The sensation experienced by individuals exposed to the same low level of electric shock varies widely.
Reported sensations range from buzzing, tingling (pins and needles), to burning or a jolt. The emotional
state of the individual at the time that the shock was received and the body location of the shock also
influence response. Shock response tends to be amplified in persons who are tense. If the shock site is
near a nerve or nerve ending that is close to the surface of the skin, the perceived intensity of the shock is
also amplified. A parallel situation is bumping one’s elbow and triggering the funny-bone response. The
physiological consequences of electric shock at different current levels (rms) for alternating current at
60 Hz are presented in Table 22.1. Threshold levels are shown. Refer to the section on Physiological Effects
for additional information.
There are various secondary effects of electric shock that can cause serious injury even if the shock itself
has produced no direct physiological damage. As with any sudden and unexpected sensory stimulus, the
startle reflex may be triggered causing the person to fall down, flail limbs, drop objects, or otherwise sustain
injury. High potentials, especially those produced by the discharge of a high-voltage capacitor, can induce
severe and generalized muscle contractions of sufficient intensity to propel an individual across a room.
Because of the violence of the reaction, the person may sustain serious bone fractures (or even death) as a
consequence of physical impact with objects in the trajectory path from the site of the shock. Even if the
victim does not collide with an object, the force of the muscle contractions alone resulting from electrical
shock may fracture spinal vertebrae or cause a shoulder dislocation.
