Reasons of electric traumas
Provide that you undertake the hands bare conductors which are under high tension, and does not beat you with electric current. Great. But it is possible in two cases: if reliable rubber gloves are put on your hands or if your skin - very good dielectric (that at ordinary people is not observed). Unfortunately, human skin - bad dielectric and therefore the contact of people with electricity , as a rule, comes to an end with various injuries and the lethal outcome.
External factors of defeat by electric current of the person is the size of the current passing through the body, influence duration, the current sort (constant, variable), its frequency, etc.
But also the result of defeat also depends on the person. It is influenced by resistance of the human body. Resistance of the body depends on the condition of the organism, the integument, its humidity, the emotional state, etc.
Usually the person is capable to feel action of electric current of small size: 0,6-1,5 milliampere (at alternating current with the frequency of 50 Hz) and 5-7 milliampere (at constant). This value of electric current has the name "threshold notable current". High values of currents are capable to cause involuntary reductions of muscles and quite painful feelings which with increase in current amplify, influencing the increasing parts of the body.
At alternating-current values at 10-15 the mA pain becomes already intolerable, and reductions of muscles of the person get the condition of insuperability. As a result of people it is not capable to unclench independently the hand in which there is the current carrying conductor with tension. Such currents have the name "not releasing". For the direct current its value corresponds 50-80 mA.
Alternating electric current with the force of 25 - 50 mA (50 Hz) affects muscles not only hands, as well as the trunk where the most dangerous zone is the thorax. In this case there is the strong difficulty of breath. Long influence of currents of this size is capable to cause even complete cessation of breath then there comes death from suffocation.
Alternating electric current (50 Hz) with size from 50 mA and up to 100 mA forces down normal action of the heart and lungs even quicker. At this value as, however, and at smaller currents, the first on time lungs are surprised, and behind them and heart.
Alternating electric current (50 Hz) with size from 100 mA to 5 A and the direct current from 300 mA to 5 A first of all influence the cardiac muscle that is extremely life-threatening the person as one-two seconds later after the beginning of electric blow there occurs fibrillation (chaotic reduction of heart fibers). At this heart ceases to work as the pump that stops blood circulation in the organism. It involves the lack of oxygen and respiratory standstill. Further clinical death. If within 7 minutes not to recover the person, then clinical death passes into the constant.
Electric current with the force more than 5 Amperes usually does not cause fibrillation of heart because at such values of current there is full cardiac arrest at once. Further paralysis of breath and besides clinical death.
If influence of electric current was short-term (up to 1 - 2 seconds) and did not entail cardiac arrest (as a result of the burn, heating, etc.), then after cancellation of current heart usually itself resumes the work, and breath does not. Therefore emergency aid in the form of artificial respiration is necessary (the mouth in the mouth or the mouth in the nose).
Important factor of defeat by electric current is the way of passing of this current on the body of the person. If on this way there are vitals: lungs, heart, the head and spinal cord, that defeat becomes very dangerous as action of current leads to violation of their work. If electric current passes on other ways, then the danger to life sharply decreases.
P.S. As practice shows, the direct current is 4 - 5 times safer, in comparison with variable (50 Hz). But it belongs to tension up to 250-300 V. Budte are attentive and careful during the work with electricity!Top