1, safe voltage standards
Safe voltage is the case without any protective equipment, the human body comes into contact with the various parts of the body's tissues, such as skin, heart, nerves, etc. without any damage to the voltage. It is often difficult to determine a maximum safe voltage that is perfectly suitable for the human body.
The regulations for safe voltage vary from country to country around the world. There are 50, 40, 36, 25, 24V and so on, many countries adopt 36V as the safe voltage. The International Electrotechnical Commission (IEC) safety voltage limit value of 50V, 25V or less can not be considered to prevent electric shock safety measures.
China's regulations 36, 24, 12V three voltage levels for the safety of voltage levels for use in different places. In the high-voltage shock risk areas for the safety of 36V, no high-voltage shock risk areas for the safety of 24V.
In the humid, conductive dust, high temperature and metal containers work, 12V for the safety of the voltage. Safe voltage regulations are from the overall consideration, for some special circumstances, some people may not be absolutely safe. It can be seen, even in the provisions of the safe voltage work, but also not careless.
2, safety distance standards
Safety distance refers to a variety of working conditions, charged conductors and the surrounding grounded body, ground, different phases of the charged conductor and the minimum distance between the staff must be maintained.
The size of the safety distance is closely related to the discharge characteristics and voltage level applied to the conductor. For lightning overvoltage, the safety distance should be decided according to the characteristics of the lightning arrester. For operational overvoltage, the safety distance is decided according to the overvoltage multiplier that may occur in the power grid.
The maximum permissible operating voltage of the power grid can be disregarded because its value will not exceed 110%. The safety distances for various situations in which the electrician's professional regulations provide for action are the credentials that electrician designers, operation and maintenance personnel must follow in their work.
Extended information:
The introduction of commonly used electrical safety standards is based on national standards, including electrical basic standards, electrical safety standards, electrical equipment and operation standards, electrical design standards, as well as the principles of drawing electrical control lines, graphic and text symbols. It is used to provide electrical staff with a guide to commonly used electrical national standards and business-related electrical technical standards.
Baidu Encyclopedia - Electrical Safety Standards