250.32(A)(A) Grounding Electrode. Building(s) or structure(s) supplied by feeder(s) or branch circuit(s) shall have a grounding electrode or grounding electrode system installed in accordance with Part III of Article 250. The grounding electrode conductor(s) shall be connected in accordance with 250.32(B) or (C). Where there is no existing grounding electrode, the grounding electrode(s) required in 250.50 shall be installed.
250.32(B)(1) Supplied by a Feeder or Branch Circuit. An equipment grounding conductor, as described in 250.118, shall be run with the supply conductors and be connected to the building or structure disconnecting means and to the grounding electrode(s). The equipment grounding conductor shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded. The equipment grounding conductor shall be sized in accordance with 250.122. Any installed grounded conductor shall not be connected to the equipment grounding conductor or to the grounding electrode(s).
JW. You did not actually answer either of my questions, I think.
1) Does the steel flex conduit count as "an equipment grounding conductor" still? Obviously, back in 1947, it did. And if so, I would be grandfathered in.
But if it is no longer permissible, even on 20 amp or smaller circuits to rely on the flex conduit as the ground path, and that a separate conductor needs to be pulled, in say, a re-wire, then that is news to me, and the inspector for the extensive rewire I did a few months back in an adjacent city certainly missed the boat on calling me out on it. Granted, that was built in '28 with black gas pipe (ships were wood and men were iron). He had me installing arc faults but no separate conductor. I certainly found low resistance to ground in my tests.
So, is it acceptable to use the conduit as a ground, or need I run a specific (green) conductor?
1a) And as a separate question: nearly none of the circuits in the house I am looking at just now are showing a valid ground at the receptacles. The ground at the main panel reads fine. In a house that is going on 70 years of age, is it a reasonable assumption that the interface of the conduit, the connectors and the boxes has all so completely corroded that no reliable ground is available.
I am writing a document on behalf of the buyer to squeeze concessions from the seller for upgrades, and I would as soon not be talking out of my ass.
2) For the out building sub panel, I know that I need ground stakes, and that that has been the standard for decades or more.
But is there a NEW requirement for a grounding conductor to bond the grounding buss bar in the sub panel to the ground/neutral buss bar in the main panel?