Current directly from the harmful effects on the human body. In general, the current through the body more than one milliampere, there feeling numb shock: current up to tens of milliamperes, electrocution on power alone is difficult to get rid of: the current over 100 mA, it could be life-threatening. From Ohm's law shows that the current through the body size is determined by the body resistance and contact with the supply voltage. The body's resistance to many factors, complete and dry skin, the resistance of up to 10-100 kilohms; broken skin or sweating, the body resistance can be reduced to the following Euro 1000. In addition, the contact area of the skin and the charged object is larger, the weight of the more tight, the smaller the resistance. If the calculated body resistance of 1000 Ohms, the contact voltage 40 volt power supply, there is a current through the body 40 mA, which is dangerous to the human body. China provides often carry hand-held lights (DRL), using 36 volts, especially when working in damp places, the use of lower voltage 24, 12 volts and so on. This low voltage is called the safe voltage. The degree of risk of electric shock and shock duration time, the current through the body pathway. Generally, the product of the human body through the shock current is greater than the duration of 50 mA · s there is a great danger. Current through a large address cardiac risk between hands or left foot from the left to the shock between the current through the heart could. Therefore, when energized electrical equipment maintenance, except that the outer safety equipment should also be possible for one-handed operation, reduce the risk of electrical shock in case.