----- Original Message ----- From: Russell McMahon To: Sent: Monday, March 19, 2001 2:39 AM Subject: Re: [OT]: Four-wire electric distribution system > > In the US common practice is to bring 3 conductors to the house/building: > > > > 2 phase conductors (180 degrees apart), each a nominal 117V from ground. > > > > 1 ground/neutral conductor. > > > > As noted below for New Zealand, the protective ground and neutral are > split > > immediately at the entrance panel to the house or building, and from that > > point on are maintained separately, including, in theory, but often not > > practive any runs to outbuildings or subpanels. > > One had better do it in practice in NZ as well or risk the wrath of > authroity. All commercially installed wiring will invariably have separate > earth and neutral runs throughout the property. I live 'in town', so when I ran a 100A 240V underground feeder to my 'barn', I had to maintain separate neutral and protective ground, but I was allowed to use #6 CU for the protective ground (much too small for a 100A load!) on the theory that any significant current in the protective ground due to a fault should be short term. In addition, I had to include a ground rod (driven 8ft into the ground) at the outbuilding connected to the protective ground. On the other hand, next month I am installing an overhead 100A feeder to run from one building to another at a campground where I volunteer , and the inspector has explicitly said that it is ok to run only a single conductor, rather than separate protective ground and neutral. This is, of course, in violation of the National Electric Code, but very common in rural areas. Bob Ammerman RAm Systems (contract development of high performance, high function, low-level software) -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics