Safe voltage refers to the voltage that the human body is exposed to without any protective equipment, which does no harm to all parts of the human body, such as skin, heart and nerves. It is often difficult to determine the highest safe voltage that is completely suitable for human body.
Countries around the world have different regulations on safe voltage. There are 50, 40, 36, 25, 24V and so on. Many countries adopt 36V as safe voltage. International Electrotechnical Commission (IEC) stipulates that the limit of safe voltage is 50V, and the safety measures to prevent electric shock can be ignored for voltages below 25V.
In China, three voltage levels (36, 24, 12V) are defined as safe voltage levels, which are used in different places. 36V in safe voltage where there is danger of high-voltage electric shock, and 24V in safe voltage where there is no danger of high-voltage electric shock.
Safe voltage is 12V when working in damp, conductive dust, high temperature and metal containers. Safe voltage's regulations are considered as a whole. For some special circumstances, some people may not be absolutely safe. It can be seen that even if you work under the prescribed safe voltage, you should not be careless.
2, the safe distance standard
Safe distance refers to the minimum distance that must be kept between live conductors and surrounding grounding bodies, the ground, live conductors in different phases and workers under various working conditions.
The safe distance is closely related to the discharge characteristics and the voltage level applied to the conductor. For lightning overvoltage, the safety distance should be determined according to the characteristics of lightning arrester. For operating overvoltage, the safe distance is determined according to the possible overvoltage multiples of the power grid.
The maximum allowable working voltage of the power grid can be ignored, because its value will not exceed 1 10%. The safe operation distance under various conditions stipulated in the Professional Code of Electrician is the evidence that electrician designers and operation and maintenance personnel must abide by in their work.
Extended data:
With the development of science and technology, systems and equipment are becoming more and more complex and their functions are becoming more and more perfect, but people's requirements for operation and maintenance are becoming simpler and easier. This requires a more global concept in the expression of electrical information, taking the complex system as a whole and giving clear symbols to each category for quick retrieval and query.
The introduction of common electrical safety standards is based on national standards, including electrical basic standards, electrical safety standards, electrical equipment and operation standards, electrical design standards, drawing principles of electrical control circuits, graphics and text symbols, etc. It is used to provide common electrical national standards and business-related electrical technical standards guides for electrical workers.
Baidu Encyclopedia-Electrical Safety Standard