4 wire feed on Sub Panel?

[jfrederick (Joshua Frederick)]

@pmccoy3

4 wire feeder on a 1970 home?

Are we talking inside the house and/or attached to the house? Or are we talking a detached garage/structure?

Need Excerpt from 1975 or earlier NEC - subpanel grounding

I am constantly, and I mean constantly finding subpanels in homes wired with 3 wire feed - meaning no 4th conductor - meaning neutral and ground are shared and bonded in the subpanel just like in a main service panel, and the subpanel is in the same building as the main panel. To my knowledge it was never acceptable to wire a subpanel in the same structure as the main panel without running both a grounded and a grounding conductor and keep them isolated. The only NEC allowed exception I am awa…