EMC Question of the Week: June 12, 2023

wrist strap on a hand holding a screwdriver

A wrist strap like the one in the figure is often worn by people working on electronic equipment to keep them from 

  1. being electrocuted
  2. damaging the equipment
  3. working too hard
  4. leaving the work area


The best answer is “b.” ESD wrist straps like the one shown in the figure bleed any accumulated charge from the wearer, preventing them from generating an electrostatic discharge that might destroy the components or test equipment they are handling. These wrist straps are connected through a large resistance to the building/equipment ground. In dry environments, people may experience triboelectric charging due to the relative motion of incompatible nonconductive materials in their clothing or furniture. Electrostatic discharge at voltages too low for a person to notice can destroy sensitive components or test equipment.

ESD wrist straps provide no protection at all from electrocution, so standard safety precautions need to be taken when working with high voltages.

A wrist strap that monitored a person's pulse or other physiological indicators might be able to recognize when that person was working too hard. But that is not the type of wrist strap shown in the figure. 

A wrist strap that was chained to the table might prevent a person from leaving the work area. But again, that is not the type of wrist strap shown in the figure.

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