Electrical Hazards
3. Factors that Intervene in Electrical Accidents
3.2. Time of exposure to the hazard
We have previously cited current intensity as the main cause of accidents through electrocution. However, one cannot speak exclusively of intensity values without relating these to the time the current is passing through the human body.
3.3. Path of the current through the human body
The influence of the path of the current on its consequences is due to the importance of the organs affected by the current as it passes through them.
Accordingly, all those paths that involve the thorax or the head are more serious than the rest.
The following examples may be cited as the most hazardous paths:
- Hand - head.
- Hand - opposite side foot.
- Right hand - thorax - left hand.
3.4. Nature of the current
Although the majority of installations employ alternating current, we shall also consider the possible existence of direct current.
a) Alternating current
Given that one of the technological characteristics of electric current is its frequency, the superimposition of the frequency over the rhythms of the nervous and circulatory systems produces an alternation that translates as spasms, shaking and an irregular heart beat (ventricular fibrillation).
In terms of the frequency of the current, we may state that high frequencies are less dangerous than low frequencies, becoming practically inoffensive above values of 100,000 Hz (only producing heating effects without any influence on the nervous system), while the danger for 10,000 Hz is similar to direct current.
b) Direct current
In general, this is not as dangerous as alternating current, although it may produce the same effects with a higher current intensity passing through the body and a longer time of exposure.
It has heating effects and may even produce an electrolytic effect in the organism that may generate a risk of embolism or death resulting from electrolysis of the blood.
The most serious effects are produced by rectified direct current.
