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severe cases, by burning. The shock can be produced by low voltages, high voltages
or lightning.
Most incidents of electric shock occur when the person becomes the route to
earth for a live conductor.

There are 4 degrees of electric shock:
1. Convulsive muscle contractions without loss of consciousness (without
prejudice to the heartbeat and breathing).
2. Convulsive muscle contractions with loss of consciousness, but without
prejudice to breathing and heartbeat (first aid is lead to memory using water,
ammonia).
3. Loss of consciousness and irregular heartbeat or breathing (First Aid is
cardiopulmonary resuscitation – CPR).
4. Clinical death is intermittent transition state from life to death, which occurs
after the cessation of the heart and lungs.

The effect of electric shock and the resultant severity of injury depend upon
the size of the electric current passing through the body which, in turn, depends on
the voltage and the electrical resistance of the skin. If the skin is wet, a shock from
mains voltage (220/240 V) could well be fatal.
The effect of shock is very dependent on conditions at the time but it is always
dangerous and must be avoided. Electric burns are usually more severe than those
caused by heat since they can penetrate deep into the tissues of the body.

The effect of electric current on the human body depends on its pathway
through the body (e.g. hand to hand or hand to foot: if the current path finds vital
organs – heart, lungs, brain – the risk of injury is very high, since current acts directly
on these organs), the frequency of the current (since the resistance of the human
body has a capacitive component, increasing the frequency of the applied voltage is
accompanied by the decrease in the impedance of the body and increase of the
current that passes through a person), the length of time of the shock (the higher the
duration, the greater the likelihood of severe or fatal) and the size of the current.
The effect of electric shock and the resultant severity of injury depend upon
the factor of attention. The factor of attention increases the resistance of the body. 85
% of the electric shock factor occurs in the absence of attention.
The current size is dependent on the duration of contact and the electrical
resistance of body tissue. The electrical resistance of the body is greatest in the skin
and is approximately 100 000 ohm, however, this may be reduced by a factor of 100
when the skin is wet. The body beneath the skin offers very little resistance to
electricity due to its very high water content and, while the overall body resistance
varies considerably between people and during the lifetime of each person, it
averages at 1000 ohm. Skin that is wounded, bruised or damaged will considerably
reduce human electrical resistance and work should not be undertaken on electrical
equipment if damaged skin is unprotected.
An electric current of 1 mA is detectable by touch and one of 10 mA will cause
muscle contraction which may prevent the person from being able to release the

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