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>From willli Fri Jul 25 10: |
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You confused me, I assume you mean EARTH ground versus electrical equipment
ground?? If this is the case, either will be sufficient from both a
personnel safety and ESD safety standpoint if installed correctly.
If using earth ground by inserting a grounding rod through the floor into
the earth, the ground rod must be electrically bonded to the electrical
equipment ground (I believe this is a National Electrical Code
requirement). This is especially true if personnel are working with
electrical equipment (soldering irons, etc.) while connected to ground. If
there was an equipment failure where a "hot" wire contacted an electrical
ground (i.e. through the equipment chassis) that charge is going to seek
the least resistive path to ground. If there was a lower resistance to
earth ground, personnel could be exposed to lethal voltage.
However ESD wrist straps/cords must have a safety resistor installed to
limit current flow in case this happens. The wrist straps and cords should
be tested daily to ensure that the resistor is functioning correctly.
Basically if facility electrical ground is per electrical code, that's the
best way to go from both a safety as well as convenience standpoint. You
might want to ensure that there is very little difference between
electrical ground and earth ground prior to committing to one method or the
other.
Hope this helps, if I am not clear on something, let me know and I'll
elaborate more (the boss gets mad when I spend 30 minutes writing one
E-Mail)
Steve McBride
Frontier Engineering Inc.
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