From: arl_123234@hotmail.com   
      
   Hello, all.  As an EE what should be a simple electrical   
   circuit/networks question has me puzzled as to the rationale, and I   
   can't find it online or in any textbooks.   
      
   Assume we are discussing a standard 120/240 V residential service in the   
   U.S.  It is required that all ground (green) and neutral (white) wires   
   supplying the inside facility be tied together at the service entrance.   
     That much I understand; if there's a hot (black) wire fault to the   
   metallic part of the device connected to the ground wire, then opening   
   of the breaker/fuse is facilitated (but not guaranteed depending on the   
   amount of the fault current).  IOW, the grounded (metal shell, etc) of   
   the device protects the user and ideally blows the fuse.   
      
   What I don't get is the need to also connect the neutral/ground wires   
   via a short path (connection to metal water pipe or ground rod(s)) to   
   contact with soil (earth). Other than perhaps lightning protection (at   
   least on the neutral/ground wire side) what other advantages accrue from   
   this earthing?  Conversely, what would you give up with no connection to   
   earth?  I presume once upon a time power distribution EEs came up with   
   this but I'd like to appreciate their thinking.  Thanks for your reply   
   and comment.  Sincerely,   
   --   
   J. B. Wood	            e-mail: arl_123234@hotmail.com   
      
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