[AT] grounds

[K7jdj at aol.com]

In a message dated 12/19/2007 6:13:29 A.M.  Pacific Standard Time, 
chill8 at suddenlink.net writes:
Wouldn't 
that create  sort of a ground grid for the whole complex if it involves 
several buildings  or structures?

Charlie,

Not prohibited as long as the neutral is  isolated and it's not under some 
special rule addressing buildings that house  farm animals.  (especially dairy). 
 In the case of dairy buildings I  suspect the wiring is inspected and then 
"adjusted" to what works.

As I  stated in previous posts there as several "it depends" problems with 
ground  systems. In buildings with sensitive communication equipment an isolated 
ground  system is frequently utilized, This does not replace  existing NEC  
requirements but is intended to supplement it to reduce noise in sensitive  
communications equipment. 

It's important to remember the main function  of ground is to cause circuit 
disconnect if a short or fault occurs.  The  McGraw Hill book points out that a 
typical ground is incapable of lighting a 40  watt lamp.
Grounding systems must work in conjunction with equipment bonding.  The code 
requires all metallic materials within a structure that "may" come in  contact 
with power be bonded/grounded. A good example would be aluminum  siding.  
Before plastic piping came on the scene all the metal plumbing  required 
bonding/grounding.  This brings about another related problem  electrolysis. 

I hope those not interested in this off topic have made  use of the delete 
key. I will try and make this my last post on the subject. I  would encourage 
anyone connecting generators or making any electrical additions  or changes get 
the necessary permits and have the inspections.  Many deaths  and losses have 
resulted from mistakes made with electrical work.  I have  seen posts on ATIS 
where connections have be made to provide backup power from a  generator by 
use of a "double male plug" arrangement and turning off the main  disconnect 
switch!  VERY BAD practice.

Gary
Renton, WA.  




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