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"Any auxiliary grounds (water pipe, building frame, ground stake) present and used at the workstation must be bonded to the equipment ground." A low resistance connector (such as metal wire) should be soldered or mechanically attached electrically connecting the building electrical system AC ground (Equipment Ground) to the Auxiliary Ground.
ESD Handbook TR20.20 section 5.1.3 includes: "The equipment ground is the preferred ground connection because all electrical equipment (soldering irons, scopes, etc.) at the workstation is already connected to this ground. Connecting the ESD protective products to equipment ground brings all components of the workstation to the same electrical potential. If, for example, a soldering iron were used to repair an ESDS item while on the table of an inspection microscope that is connected to auxiliary ground, a difference in electrical potential could exist between the iron and the ESDS item. This difference in potential could cause damage to the item. Any auxiliary grounds (water pipe, building frame, ground stake) present and used at the workstation must be bonded to the equipment ground. Bonding the auxiliary ground and the equipment ground together will minimize differences in potential between the two grounds."
The minimum recommended technical requirement range of ANSI/ESD S20.20 Table 1 for Grounding Systems is < 1.0 ohm AC Impedance per ANSI EOS/ESD S 6.1.