Steve, were you referring this post to me? 
Regards,  Doug 

From: [log in to unmask]
To: [log in to unmask]
Subject: Re:  ESD ground vs Electrical ground
Date: Friday, July 25, 1997 12:50 PM

     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.

***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To subscribe/unsubscribe send a message <to: [log in to unmask]>   *
* with <subject: subscribe/unsubscribe> and no text in the body.          *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact   *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask]      *
***************************************************************************