Mark P Posted May 17, 2011 Report Share Posted May 17, 2011 Do you know (based on the NEC) if a sub-panel installed in 1978 required the seperation of the grounds and neutrals with the neutrals floating - like today? Link to comment Share on other sites More sharing options...
Jim Port Posted May 17, 2011 Report Share Posted May 17, 2011 A lot would depend on whether this was in the same building or a detached structure and if there were other metallic paths like a phoe or water line run between the 2 buildings. More info is needed. Link to comment Share on other sites More sharing options...
Mark P Posted May 17, 2011 Author Report Share Posted May 17, 2011 All in same building. Link to comment Share on other sites More sharing options...
Jim Port Posted May 17, 2011 Report Share Posted May 17, 2011 That is before my collection of code books goes back. Perhaps Jim K can dig up an answer. Link to comment Share on other sites More sharing options...
Brandon Whitmore Posted May 18, 2011 Report Share Posted May 18, 2011 If memory serves correctly, Jim said he can trace the requirement back to the early 1900's. I think that if you do a search, the answer should pull up. Link to comment Share on other sites More sharing options...
kurt Posted May 18, 2011 Report Share Posted May 18, 2011 I recall Hanson, Katen, and Cramer all indicating it goes back to the 1920's. Link to comment Share on other sites More sharing options...
Jim Katen Posted May 18, 2011 Report Share Posted May 18, 2011 All in same building. In that case, the sub panel grounding conductors and neutral conductors were supposed to be isolated. Just like today. My reference is the 1975 NEC, Article 250-61(b). I can personally only trace this back to the 1947 NEC. Douglas has traced it back further, but I'm not sure about the edition. For some reason 1923 sticks in my head. Jim Katen, Oregon Link to comment Share on other sites More sharing options...
Richard Moore Posted May 18, 2011 Report Share Posted May 18, 2011 All in same building. In that case, the sub panel grounding conductors and neutral conductors were supposed to be isolated. Just like today. My reference is the 1975 NEC, Article 250-61(b). I can personally only trace this back to the 1947 NEC. Douglas has traced it back further, but I'm not sure about the edition. For some reason 1923 sticks in my head. Jim Katen, Oregon Other than GECs, would there be any grounding conductors before 1947? Link to comment Share on other sites More sharing options...
Jim Katen Posted May 18, 2011 Report Share Posted May 18, 2011 All in same building. In that case, the sub panel grounding conductors and neutral conductors were supposed to be isolated. Just like today. My reference is the 1975 NEC, Article 250-61(b). I can personally only trace this back to the 1947 NEC. Douglas has traced it back further, but I'm not sure about the edition. For some reason 1923 sticks in my head. Jim Katen, Oregon Other than GECs, would there be any grounding conductors before 1947? Yes. While there weren't equipment grounding conductors as we know them today, many of the old electrical books discuss grounding of conduits, cable sheaths, cabinets, frames, & so on. Link to comment Share on other sites More sharing options...
gpdewitt Posted May 18, 2011 Report Share Posted May 18, 2011 For awhile there, the conduits and boxes WERE the equipment grounding method. My 1964 home was built with grounded receptacles (3 prong) which relied on conduits for grounding. Link to comment Share on other sites More sharing options...
Mark P Posted May 18, 2011 Author Report Share Posted May 18, 2011 Thank You Gentelmen & have a wonderfuly Wednesday! Link to comment Share on other sites More sharing options...
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