Was there ever a code cycle that allowed neutral wires and equipment grounds to be bonded at a sub panel with a four wire system? It is a issue that I come across on a considerable about of older homes. It make me wonder if there was ever a point that it was acceptable in the NEC or a major fail on for the local authority.
Previous Code cycles regarding separation neutral and equipment grounds in sub panel
- Thread starter Alpenglow
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david
Senior Member
- Location
- Pennsylvania
If the neutral and equipment ground are connected to the same bus at the service equipment and the neutral and the equipment ground bars are bonded together at the sub-panel you would be in effect paralleling the neutral conductor between both panels. There would be no point in installing four conductors between the panels.
I do not know of a code cycle that this was ever allowed as you described the feeder.
Hi and stay warm
I do not know of a code cycle that this was ever allowed as you described the feeder.
Hi and stay warm
- Occupation
- Licensed Electrician
I agree and am unclear by what you mean by 4 wire sub panel. I don't re-bondig the neutral at a sub was ever allowed. I do think it was tolerated or slipped by a lot in the old days.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
That was still legal in the 2005 NEC.
- Location
- Simi Valley, CA
That might be what he was seeing.
Feeder "A" Black, Feeder "B" Red, White Neutral, bare or green ground. It is common to have a outside disconnect here in Alaska, mostly because that is a requirement in Anchorage, so the service entrance becomes the proper point to bond. The main load center becomes a sub panel, where in many parts of the country that load center would be the first point of disconnect. I speculate that it falls into the category of "electricians" just landing the wires where they are familiar with. I agree that this situation was tolerated or slipped by a lot, I would say at least 25% of the houses I work on have this same issue. Only being an electrician for a relativity short period, I sometimes have to catch myself from judging things from recent standards. I actually found old 1971 and 1975 PDF code books on line and found consistent language about objectionable current flow is in NEC 250 which would make binding a sub panel unacceptable. When customers look at me like I am crazy for telling them that the the panel that has been in the house for forty, fifty, sixty years is wired wrong, I try to explain why and when requirements changed. I feel that I can say with certainty that it was not allowable at the time the home was constructed.
Non-compliant being objectionable current on the grounding conductor... but in many to most cases not an imminent threat to life or property.
jxofaltrds
Inspector Mike®
- Location
- Mike P. Columbus Ohio
- Occupation
- ESI, PI, RBO
I thought Karl Riley once quote 1934 but I could be wrong.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Oldest book I have, 1940 NEC:
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