A circa 1980 condo in a six-story building that is part of a very large complex. The FPE panel was replaced recently (almost certainly without a permit). All the outlets show grounded, but when I pulled the panel cover, there are no circuit grounding conductors at all. One grounding wire for the service coming in. The main disconnect is in a locked electrical service room, so this panel is a sub to it. In the first photo, I note that the green screw is screwed down, but since it is not bonded to the floating neutral bar on the opposite side of the breakers and there are no conductors to it all, it doesn’t matter.
So how are these outlets grounded? Maybe metal boxes and conduit which would make sense for a commercial building like this. When I pull an outlet cover, there is a grounding conductor terminated at the outlet grounding lug. I didn’t pull the outlet, but it was clearly in a metal box, so maybe the circuits are still grounded through conduit. I feel like I am having a brain fart and missing the obvious. I would have thought the circuit grounding conductors would go back to the grounding bar in the sub panel, but nope. Could the grounding conductors go all the way back to the main disconnect? What am I missing?
I believe the steel conduits are an acceptable ground path. It grounds through the conduit, so no ground wire run is needed. Unless I’m missing something… which is always possible
It is likely that the junction boxes all have metal conduit running back to the panel, and the grounding conductor at the recep connects to the back of the metal junction box. But that would only be verified by pulling the recep out further.
And the main service panel probably also uses metal conduit as the EGC to the subpanel.
I find it done this way often on older condo units.
Always a possibility, but does not explain the outlet picture with the GC under the outlet ground screw. A metal box and conduit assembly would provide the outlet ground without additional wiring.
Back in 1980 the building was probably apartments. This is a sub panel so the neutral conductor should NOT be bonded to the panel. If metal conduit is present that is likely the ground path.
Had a flip like that a couple years back (single family home). I wrote it up as needing an electrician. No circuit grounds in the panel. All outlets tested good - NM wiring.
The GC in the photo is probably a bonding jumper between the grounding terminal of the receptacle and the metal box. It was likely required at the time of construction. Maybe @rmeier2 could shed some light on that.
I agree, a bonding jumper is required from a metal box to a receptacle unless the device is a listed self-grounding device, typically with the clip on one or both of the mounting screws. It does appear that since there are no visible branch circuit EGC’s that the metal raceways are being used as an EGC which is permitted by the NEC.
No contact other than the clip to the 6-32 screw. The setback of the box from the surface is permitted to be up to 1/4" with a non-combustible finish like drywall so there often (as shown in the photo) isn’t any yoke to box contact.
Something that I was unable to get a good photo of is the GC that is coming from the NM. Where do you guys think the other end of that GC is terminated?
Do you mean the ground ran with the feeders as shown in the pic below? If so, it would be terminated at the main, bonded to the service neutral. That would also mean the feeders are likely not in a metallic conduit.
I meant the circuit GCs. While the other end of the EGC was probably at the main in the locked electrical room, it is the individual circuit GCs that I wonder where they are terminated.
I couldn’t get a good photo of the back of the receptacle box, but I thought I could see the cable sheathing in the back of the box, so I think NM was used for some of the wiring. But on reconsideration, I could be wrong.
As a side note, I will pull an outlet when I really think I need to, but I think it is best advice for most HIs under most circumstances to refrain from pulling the outlets or switches. It is particularly dangerous with grounded metal boxes. So, to practice my own advice, I didn’t pull this outlet, because I was more curious about the grounding than concerned about it.
My panel photo was out of focus. I typically take 4-6 closer up photos.
