When is esd protective area signs not requried at the entrance to esd control work area?

Answer 1

For not needing at least one sign at the entrance of an ESD protected area, the answer likely is never. The issue is how do all people, including visitors, know that it is an EPA, and that special precautions are required including grounding all conductors including people.

The ESD Association document specifying requirements for ESD control programs is ANSI/ESD S20.20. It says "Caution signs indicating the existence of the EPA shall be posted and clearly visible to personnel prior to entry to the EPA." [ANSI/ESD S20.20 section 8.3]

There is also a 130 page ESD Handbook ESD TR20.20 to provide guidance.

"Appropriate signs and markings must identify protected areas so that all people entering the area, including visitors, are aware that special precautions are needed. Packaging and containers that enter the protected area must be approved for use based on the expected movement within the protected area. Transportation of sensitive items between protected areas or to unknown or uncontrolled destinations may require higher levels of static protection."

There is an example of an EPA Caution Sign per ESD TR20.20-2008 Figure 18 "Example of an EPA Caution Sign", the text is "Caution, ESD Protective Area, Use Electrostatic Discharge Protective Handling Procedures"