Replies

1. 
   John_Sprung | May 04, 2001 01:40am | #1

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   Neutral and ground are connected at the service entrance to give the system a known relationship to true earth ground. If the system were allowed to float, it wouldn't reliably remain floating. Something would get shorted to true earth, so the safest thing to do is put that reference to the middle.

   Neutral and ground are kept separate from each other everywhere else, so that all the return currents flow through the neutral, never the ground. If the grounding system were allowed to carry currents, an open somewhere in it would put everything downstream of the open hot at a low impedance, a very dangerous situation.

   -- J.S.

1. 
   Western_Tool_Nut | May 04, 2001 04:19am | #2

   *If you leave the bus bar in a sub-panel, I have seen all the copper water lines in a house take a charge, sucks to try and work on the plumbing then!Still twitchingWTN

2. 
   john_fuhrmann | May 04, 2001 04:19am | #3

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   In main service panels a tie bar connects the neutral and grounding buses.In a subpanel not so. Why? Thanks.