I’ve been reviewing many similar posts and just want to make sure that I’m understanding the bonding and GES requirements for this detached garage. I think this is the first setup where I could actually view a metallic path between the garage and the main home and wondering what importance that metallic path has to the bonding requirement.
Today’s inspection was on a 1954 build SFR with a detached garage (shared roof). The detached garage had a sub panel with a 4-wire feeder, no apparent GES, and an apparent metallic path to the main home via exterior conduit. The EGC & Neutral feeder, grounding conductors, and grounded conductors landed on the neutral bus (not separated). The neutral bus was not bonded to the enclosure and there was no ground bus. For kicks, I checked continuity between the sub panel enclosure and neutral bus and there was no continuity. I was expecting to see continuity because of the metallic path back to the service panel. The metallic path is what I think is tripping me up. What relevance does the metallic path have on the setup I observed today?
Here’s my understanding: this detached garage requires its own GES and ground bus to be installed and bonded to the enclosure. A (newly installed) GEC, EGC feeder, and grounding conductors should land on a newly installed ground bus. The neutral feeder and grounded conductors should land on the neutral bus which is not bonded to the enclosure. The metallic path only reinforces the requirement for the neutrals and grounds to be separated to prevent a parallel path.
How close am I on my understanding of the correct bonding & grounding requirements for this setup?
First off, if the home was built in 1954, you should look at it through that lens- so, go back to black and white… I don’t know your jurisdiction, but where I am in the 50’s nothing was grounded other than bath and kitchen outlets- and only in some cases (royalty, I think). I have absolutely no idea what the code was back then on sub-panels, but I would make my comments broader- Bryant electrical service panel is very dated and obsolete, may be functional but parts are not available if needed, etc.- recommend consulting a qualified electrician for a better understanding of the risks and options. You might mention safety concerns with breakers that have been installed for 70 years, outside no less. There’s a good chance they won’t trip when they should. In my humble opinion, the ground path on the sub-panel may be the least of their worries. Now ask me about the roof…
I think you are largely on-the-money with your assessment. Needs a GEC, ground rod, and the enclosure grounded, minimum. Your continuity test on the neutral confirms that the neutrals are indeed isolated from the enclosure (as well as the EGCs on the same bus). Whether the EGC’s need to be isolated from neutrals is a judgement call. When the garage was built the subpanel was code compliant with grounds and neutrals not isolated. Today would be different, especially if the subpanel was in the same building. I think the reason for the change in code is the concern that many of the EGCs within a home could become energized if the neutrals and grounds are not isolated in the subpanel. In your case, there is very little chance that any of the wiring in the garage shares an EGC with anything in the main house, so very little concern in that regard.
Thanks for the reply. The lens I’m using is at least two-fold. The date that the detached garage panel was upgraded (which I don’t know) and the safety implications. That panel is not original to the home which I’m sure you know. I’m using today’s inspection as a case study to learn from. Today’s inspection had a couple facets that was throwing me off.
LOL, the entire home is severely dilapidated and will be noted in the report. It was an elderly couple that had dementia, passed away, and the kids were not aware of the situation. Now they’re selling it and want the report for the seller disclosure.
Thanks Brian. You were on quite a few of the past posts that I was reviewing. I almost quoted a couple of your past posts but I decided to create a new topic instead
What you are saying doesn’t make sense. You said that the grounded (neutral) conductor and EGC are terminated on the same terminal strip, but there was no continuity between them. That’s impossible.
I think I’m gonna need a referee or conscientious objector on this one, LOL
Edit: I changed my mind…
@gwells
Please provide the statement that you’re referring to in my post where I said that there was no continuity between the grounded (neutral) conductor and the EGC that were both terminated on the neutral bus. You won’t find that statement in my post because I did not say it, sigh. The only statement I made was that there was no continuity between the sub panel enclosure and the neutral bus.
OK, maybe I misunderstood what you said. I don’t understand how the EGC and grounded conductor can be on the same terminal strip but not have continuity between the enclosure and the EGC unless, of course, the EGC is not connected to the enclosure and there is not a metal path between the house and the remote panel. But, if it’s a four-wire feed, it’s odd that someone would have run the fourth wire and not put it a terminal strip for the ground.
Agreed. That’s why I was asking for help to understand this setup and making sure that my observations were correct. There was a lot of substandard electrical work performed all over this home.
Apparently the conduit isn’t doing more than protecting the conductors. Since, someone put in a 4-wire feed to the sub from the service panel, then, the sub is wired incorrectly with the grounding and grounded conductors on the same bar regardless of age. Gotta say, not only would I have never tested the conduit for continuity between the panels, I don’t even have the equipment to do that kind of test.
As a side note, those kinds of houses are sometime easy inspections. “Everything needs fixing. I accept credit cards, check, cash, Venmo.”
A separate single-story building, without a basement or crawl space, used for the storage or use of hazardous materials and located an approved distance from all structures.
