Questions And Answers

In ANSI/ESD S20.20-2007 Table 1, common point ground was removed as “implementing process”. I would think that it really does not fit as an implementing process; rather one can and should use a common point ground whether using Equipment Ground, Auxiliary Ground, or Equipotential Bonding.

Common Point Ground occurs many places in Handbook ESD TR20.20-2008 including:

Section 5.1.3 Basic Grounding Requirements “The first step in ensuring that everything in an EPA is at the same electrical potential is to ground all conductive components of the work area (i.e., worksurfaces, people, equipment, etc.) to the same electrical ground point. This point is called the common point ground and is defined by ANSI/ESD S6.1 as "a system or method for connecting two or more grounding conductors to the same electrical potential." Figure 12 shows the symbol that is used to identify and label this common point ground.
A work area equipped with materials and equipment to limit electrostatic voltages is called an ESD protective workstation. Every element to be grounded in an ESD protective workstation is' attached or connected electrically to the same common point.
The next step in completing the ground circuit is to connect the common point ground to the AC equipment ground or an auxiliary ground, as defined in ANSI/ESD S6.1.”

Section 5.3 Protected Areas“In the broad sense, an EPA is capable of controlling static electricity on all the items that enter that work area. Personnel and other conductive or dissipative items must be electrically bonded together and attached to a common point ground terminal (or recognized bonding point) to equalize electrical potential among the items.”

From grounding standard ANSI/ESD S6.1 “Level 2 Technical Elements: Any ESD technical element that is connected in series to common point ground or to a common connection point through another technical element.” [Grounding ANSI/ESD S6.1 section 3.0 DEFINITIONS]  Examples shown in ESD S6.1 Figure 1A are Standing Person, Chair, and Cart with Conductive Wheels all level 2 as grounded via “ESD Floor/Mat”, not directly to the Common Point Ground.