EMC Question of the Week: February 6, 2023

ISO 7010 - Yellow triangle with a black arrow-tip spark shape

The symbol in the figure indicates the presence of 

  1. ESD sensitive components
  2. an ESD ground
  3. lightning protection
  4. dangerous voltages


The best answer is “d.” This symbol is defined in ISO 7010 (W012) and indicates an electricity hazard. It is widely used to indicate the presence of dangerous voltages. It can be found on fences enclosing high-voltage equipment, panels that access high-voltage wiring, and on power supply enclosures in electronic products. Enclosures with this symbol should not be accessed by untrained personnel. 

The presence of ESD sensitive components can also be indicated by symbols found in a yellow triangle. Two standard symbols are shown here. 
ESD Sensitve Device symbols: hand with a line through it and circle with three inward pointing arrows 

Symbols similar to the ISO 7010-W012 symbol that have a yellow triangle with black spark shapes are also sometimes used to indicate unsafe voltages. These symbols and the ISO 7010-W012 symbol generally indicate threats to the safety of personnel, not just vulnerable components.

Occasionally, one will find an example of the ISO 7010-W012 symbol being used (along with accompanying text) in situations that do not represent an actual safety hazard. While this practice is discouraged, it is not necessarily illegal. To be safe, one should always assume that dangerous voltages are present wherever the ISO 7010-W012 symbol is found.

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