Electric current is the flow of electrons; which is electricity. When electricity passes through the human body, the nervous system undergoes an electric shock. The severity of the shock depends mainly on the intensity of the electric current, the path taken by the current through the human body, and the duration of contact. In extreme cases the electric shock leads to the failure of the normal action of the human organ that is the heart and lungs, resulting in unconsciousness or death.
The truth is electric current between, 10 to 20mA current is very dangerous because any who allows such current to pass through him or her either by mistake or consciously suffers losses in muscular control. Why this is true, the resistance of the human body between two hands or between two legs ranges 500mA to 50kΩ. Assuming the resistance of your body is 20kΩ, then you are in contact with 230volt supply that can be potentially fatal, because 230/20,000 = 11.5 mA.
The leakage current I = V / R, where V is the supply voltage and R the body resistance. The resistance of dry human body varies from 70kΩ to 100kΩ per square cm, but when the human body is in contact with water or is wet, it reduces immensely to between 700Ω to 1kΩ per square cm. (The skin resistance of the body is high, but internal resistance is low).
To analyze the effect of the wet body, it can be said that 100v power supply to wet body, is as dangerous as 1000 volts to the human body when it is dry.
Effect of Electric Current Passing from Hand to Hand and Foot to Foot
Below are the effect of electric current flowing from hand-to-hand and foot to foot when in contact with electricity.
- The cognition of electrical shock is about 1mA. At this level, an insignificant exciting sensation is felt by the person when there is contact with an electric field.
- The highest limit of current at which a person is capable of releasing a conductor by using muscles which is directly affected by the current is called “Let Go Current“. This current is taken to be 9mA for males and 6mA for females.
- If the current level is beyond” Let Go Current ”than the person loses the ability to control his muscles and such electric currents are difficult to bear. Though, these currents are in the range of 20mA-100mA. These current causes physical disability or injury, however, heart and respiratory function continue well.
If the current is above 100mA, then the accident could be very deadly because the pumping action of the heart stops and pulse vanishes. As soon as the heart stops pumping the brains gradually die and after it is deprived of oxygenated blood. Though when current of 6mA and above passes through someone, there is a danger of respiratory paralysis and burns.
electrical shock experienced through AC and DC may vary in their effects. The AC at frequencies (25-60c/s) is very deadly than DC of the same RMS.
The frequent use of high-frequency equipment adds more danger arises from the passage of high-frequency current through the body. Whenever one receives electric shock at the frequency above 100c/s, the sensation of shock begins to vanish. At this point there are serious internal burns that may prove to be more dangerous. The fact remains it is an electric current which kills.
Note; An alternating voltage of 50v might produce a dangerous 50mA current. Though people have survived much higher voltage due to various factors. One of such is, the contact resistance can be significantly high due to increase by dry skin, cleaning of clothes, and the wearing of thick rubber boots.