ESD Systems - Questions And Answers

I have received mixed opinions (in literature and verbal communications) regarding the most effective method of running ground connections to ESD shelving, workstations, etc. Could you give me your insight as to the pro's/con's of using Earth ground (via water pipe...) vs. Electrical ground (via a workbenches electrical ground). To me, it seems that Earth grounding everything in the facility would keep the entire production area at very near the same potential, and other than the upkeep and wiring of this system, would be ideal. Using Electrical ground seems to throw a few variables into this. Different ground lines possibly having different resting voltage potentials, and possible safety issues? But, using electrical grounds would simplify the system, make it more modular, and therefore possibly have a positive impact on the system actually working, due to ease of up-keep. Please let me know what you think. - Anonymous, Colorado Springs, CO,

From the ESD Association Grounding standard, ANSI-EOS/ESD S6.1, "Every element to be grounded at an ESD protected station shall be connected to the same common point ground. When a separate grounding electrode (auxiliary ground) is present or used in addition to the equipment grounding conductor it shall be bonded to the equipment ground at each ESD protective station to minimize the difference in potential."

From ANSI/ESD S20.20, section 6.2.1., Requirements on Grounding/Bonding Systems shall be used to ensure that ESDS items, personnel and any other conductors (e.g. mobile equipment) are at the same electrical potential. As a minimum, ESDS items, personnel and other related conductors shall be bonded or electrically interconnected.

6.2.1.2. Grounding / Bonding Systems Guidance
In most cases, the third wire (green) AC equipment ground is the preferred choice for ground (The color of third wire equipment ground can vary with local, national or international electric codes). When the third wire AC equipment ground is not available or impractical to use, personnel should be bonded or electrically connected to a conductive element of the ESDS item using a wrist strap or other grounding system to ensure that all elements are at the same electrical potential.

Earth grounds derived from water/drain pipes or other non-direct power ground connections should also be bonded to equipment (power) ground so that all grounds in an ESD Protective environment are at the same potential.

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