Electric shock injuries and deaths caused by the use of electricity in industrial equipment are a typical Class I hazard. According to data from the National Bureau of Statistics, the number of people who died from electric shock in China in 2016 alone reached 8,000 .
Industrial equipment, due to its high voltage level and harsh operating environment, makes the industrial sector a high-risk area for electric shock injuries and fatalities.
To prevent electric shock accidents in the industrial sector, it is necessary to provide electrical safety training to relevant personnel, ensuring they possess the corresponding qualifications and are certified to work. Furthermore, essential safety structures are the foundation and basis for ensuring electrical safety. For industrial equipment, GB/T 5226.1 "Electrical Safety of Machinery - Electrical Equipment - Part 1 : General Technical Conditions" provides specific design requirements for preventing electric shock.
Two common types of electric shock and their analysis
The GB/T 5226.1 standard classifies the causes of electric shock into the following two types:
Direct electric shock: Under normal circumstances, touching a live conductor when the insulation is intact will result in electric shock.
A common safety design flaw leading to direct electric shock is that opening the electrical cabinet reveals a design flaw that allows direct contact with live parts (as shown in Figure 1). The main reason for this is that designers and users lack sufficient understanding of what constitutes a live conductor as defined in standards, and the appropriate level of protection required for such conductors. Consequently, they fail to provide effective protection for live conductors that should have been properly protected.
Figure 1 : Safety design flaws leading to exposed live parts (electrified bronze plate)
Indirect electric shock: Electric shock caused by leakage due to insulation failure under abnormal conditions.
There are many possible causes for indirect electric shock. One typical situation is that the grounding protection conductor was not designed and laid out according to the requirements of the standard, which resulted in the safety protection device being unable to disconnect the fault circuit in time after a leakage occurred, thus causing the risk of electric shock.
Figure 2 shows a safety design flaw that leads to indirect electric shock (misuse of grounding wire and multiple grounding).
The correct way to ensure electrical safety in industrial equipment
To avoid electric shock, it is necessary to examine various aspects such as the design, installation, and power supply of the equipment. Ultimately, it is essential to start with risk assessment and conduct a comprehensive evaluation of the electrical risks of industrial equipment. This includes thoroughly checking the selection of electrical components, the design of electrical circuits, the installation of electrical structures, and the operating environment of the equipment in accordance with relevant safety standards. Only in this way can we ensure electrical safety in the end.
