Electric shock is a reflex response of a body when electric current passes through it.
How does electric shock occur?
An electric shock occurs when the body comes into contact directly or indirectly with any live electric circuit and the ground simultaneously.
Electric shock occurs because of the conduction of electric current in living organisms. It could be you, an animal, a bird or a tree. As a matter of fact, electricity always flows to the ground. By its own characteristics, electricity takes the shortest route to travel. It always finds a connection, which offers less resistance (or a better conductor) for its travel.
Metals and water are good conductors of electricity. Your body contains a lot of water. So you are a great conductor of electricity. If your body touches an electric circuit and the ground at the same time; electricity will travel to the ground through you.
As a result of this flow, you may be seriously injured or killed, even if you have no direct contact to the electric circuit and the ground simultaneously. The connection may be through a metallic ladder (a good conductor of electricity).
Effects of Electric Shock:
The primary variable for determining the severity of electric shock is the electric current which passes through the body. This current is of course dependent upon the voltage and the resistance of the path it follows through the body. An approximate general framework for shock effects is as follows:
Electric Current Physiological Effect
(1 second contact)
1 mA : Threshold of feeling, tingling sensation.
10-20 mA : "Can't let go!" current - onset of sustained
muscular contraction.
100-300 mA : Ventricular fibrillation, fatal if continued.
Note: mA (milli ampere i.e. one thousandth of an ampere). Ampere is a measure of electric current. Beyond 300 mA, the flow of current to the body can prove fatal, if the shock continues. So take care. For example, a bird can sit on a high-voltage wire without harm, because both its feet are at the same voltage. Secondly the bird is not 'grounded'. You will not receive a shok by touching a high voltage wire if there is no path for the current to reach the Earth or a different voltage point. If you have insulating shoes that prevent a low-resistance path to ground, you can escape serious shock even if you touch 220-volt circuit with one hand.
The role of electric current in electric shock: The severity of electric shock is mainly determined by the electric current (the most physiological variable) in amperes. This current is dependent on the voltage and the underlying resistance, You find that a voltage some times produces a mild tingling effect where as in different circumstances, it can be a lethal shock hazard. So establishing electrical safety in such conditions is quite difficult. Does 220-volt common domestic voltage produce electric shock ? It depends.
Case 1: In normal circumstances your body resistance is say 100,000 ohms. Then the current flow would be: I = 220 volts / 100,000 ohms = 0. 0022 = 2.2 mA (This does not do any harm. It produces a tingling effect only)
Case 2: Let us say you are sweating or wet and bare footed, then your body resistance might be as low as 1000 ohms. Hence in this case I = 220 volts / 1000 ohms = 220 mA (This is a lethal shock, quite capable of producing ventricular fibrillation and death. So please be careful.
Inference: The severity of shock from a given source will depend upon its path through your body.
How does electric shock occur?
An electric shock occurs when the body comes into contact directly or indirectly with any live electric circuit and the ground simultaneously.
Electric shock occurs because of the conduction of electric current in living organisms. It could be you, an animal, a bird or a tree. As a matter of fact, electricity always flows to the ground. By its own characteristics, electricity takes the shortest route to travel. It always finds a connection, which offers less resistance (or a better conductor) for its travel.
Metals and water are good conductors of electricity. Your body contains a lot of water. So you are a great conductor of electricity. If your body touches an electric circuit and the ground at the same time; electricity will travel to the ground through you.
As a result of this flow, you may be seriously injured or killed, even if you have no direct contact to the electric circuit and the ground simultaneously. The connection may be through a metallic ladder (a good conductor of electricity).
Effects of Electric Shock:
The primary variable for determining the severity of electric shock is the electric current which passes through the body. This current is of course dependent upon the voltage and the resistance of the path it follows through the body. An approximate general framework for shock effects is as follows:
Electric Current Physiological Effect
(1 second contact)
1 mA : Threshold of feeling, tingling sensation.
10-20 mA : "Can't let go!" current - onset of sustained
muscular contraction.
100-300 mA : Ventricular fibrillation, fatal if continued.
Note: mA (milli ampere i.e. one thousandth of an ampere). Ampere is a measure of electric current. Beyond 300 mA, the flow of current to the body can prove fatal, if the shock continues. So take care. For example, a bird can sit on a high-voltage wire without harm, because both its feet are at the same voltage. Secondly the bird is not 'grounded'. You will not receive a shok by touching a high voltage wire if there is no path for the current to reach the Earth or a different voltage point. If you have insulating shoes that prevent a low-resistance path to ground, you can escape serious shock even if you touch 220-volt circuit with one hand.
The role of electric current in electric shock: The severity of electric shock is mainly determined by the electric current (the most physiological variable) in amperes. This current is dependent on the voltage and the underlying resistance, You find that a voltage some times produces a mild tingling effect where as in different circumstances, it can be a lethal shock hazard. So establishing electrical safety in such conditions is quite difficult. Does 220-volt common domestic voltage produce electric shock ? It depends.
Case 1: In normal circumstances your body resistance is say 100,000 ohms. Then the current flow would be: I = 220 volts / 100,000 ohms = 0. 0022 = 2.2 mA (This does not do any harm. It produces a tingling effect only)
Case 2: Let us say you are sweating or wet and bare footed, then your body resistance might be as low as 1000 ohms. Hence in this case I = 220 volts / 1000 ohms = 220 mA (This is a lethal shock, quite capable of producing ventricular fibrillation and death. So please be careful.
Inference: The severity of shock from a given source will depend upon its path through your body.
No comments:
Post a Comment