Q: Is it necessary to use the ESD garments? Is it not possible to ground the charges developed through a person’s clothing through the human body which is grounded through a wrist strap, footwear or heel strap while working at an EPA?
A: This depends who’s in charge. If the ESD manager wants to require ESD personnel clothing and redundancy of ESD compliance for improved ESD control, they are the one to determine that. More and more I’m seeing the use of ESD smocks outside of the cleanroom environment. The company and their clients are reaping the benefits of increased quality control and reduced “out of box failures”. Cloth is proven to be a better conductor of ESD charges than some types of clothing, but not everybody wears cotton. Some people have dry skin and the ESD garments are a good idea for added protection and a requirement in some environments.
I’d like to add that when seated in an EPA, you must have your wrist strap on regardless of ESD Garments, ESD footwear, ESD flooring system, etc. That’s a requirement of ANSI/ESD S20.20-2007 page 4 section 8.2 Personnel Grounding; “When personnel are seated at ESD protective workstations, they shall be connected to the grounding/equipotential bonding system via a wrist strap system.”
Further, per Table 2 note 2, “For situations where an ESD garment is used as part of the wrist strap grounding path, the total system resistance including the person, garment and grounding cord shall be less than 3.5E7 ohms.”