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Re: More mid-point ground stuff

> Tom,  I have a question about this concept that you are talking about 
> here.  How do you determine what is a ground?  Does it need to be an 
> earth ground?  Can you ground to, lets say suspended ceiling framework?  
> or how about water pipe?  Whats it all about?
> Thanks 
> Howie
> 

I can add a little to this.  It is my understanding that the NEC actually
requires GTO in conduit for this home run back to the trans. ground.  My
experience in the field (from looking at and repairing other shop's stuff)
is that people often use regular wire, or even bare #12 wire for this run. 
I have also seen other stuff used, like a metal roof, gutters, and a
building itself if it's metal. 

The same is true of channel letter installations.  Often I've seen the
outer most electrodes simply grounded to the raceway or cabinet.  While
all of these methods work, I still think GTO in conduit is what's
code-required.  

As far as "what ground" to use - at the very least it must be the same
ground to which the transformer & it's box are connected.  Usually by the
ground and/or neutral wire from the main breaker box.  This in turn is
usually connected to an "earth ground." 

     -John Anderson