Was recently inspecting a 1918 multi-unit (all separate structures) property in LA and came across 3 subpanels (one of which was inaccessible). The subpanel closest to the main distribution panel shows two hots and one neutral at the neutral busbar, with only a little green 12awg wire on the bottom left corner. Am I correct to say this is wrong? The next subpanel did have a multistrand copper line serving as a ground, but why was it missing in the first subpanel?
The neutrals for all the subpanels are likely bonded to a single GEC at the main disconnect(s). You should verify that… There were (are) no EGCs from the main disconnect(s) to the subpanels, which was common for that era, as well as no EGCs in the unit cabling, which means that there are likely no grounded receptacles anywhere within the units (which I think is a problem if you want to use modern appliances like computers and big screen TVs, but some might argue that is all just fine). The small ground wire is for the subpanel enclosure itself, which is required and all the subpanel enclosures should likewise be grounded.
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Due to personal items and a giant barking dog, this main panel was inaccessible 
My receptacle tester was reading grounded outlets in the property (I was only able to check a few due to personal items) . Does that indicate that there was a GEC at the main disconnects?
Did the small ground wire look undersized to you? The other subpanel had a larger multistrand copper as its ground
Most likely. However, the thing you have to be keenly aware of in these situations is that your standard receptacle tester cannot detect bootleg grounds. From ChatGPT:
A bootleg ground, also known as a “false ground” or “unauthorized ground,” refers to a situation where an electrical ground connection is created or derived from an unintended or improper source. In electrical systems, grounding is essential for safety, providing a path for excess electrical current to safely dissipate into the ground.
In the context of bootleg grounds, this typically involves connecting the ground wire of an electrical device to a neutral wire instead of a proper ground. While it may appear to provide a grounding function, it can be hazardous because it doesn’t offer the same level of protection as a true ground connection.
Bootleg grounds can lead to several safety issues, including electric shock hazards and increased risk of electrical fires. It’s crucial to ensure that electrical systems are properly installed and grounded according to electrical codes and standards to maintain safety and prevent such hazards.
They make receptacle testers that can detect bootleg grounds, but they are pricey. If you are not seeing ground wires (EGCs) within the subpanels (I don’t in your pictures), it is unlikely that they were connected through somewhere else (although that is certainly possible, of course). I am pretty sure that the test button on a GFCI receptable, and for sure your receptable tester, will not work without a proper ground. Lacking that, the only sure-fire method to detect bootleg grounds is to open up a receptacle to see if someone installed a jumper wire from the neutral to the ground terminals.
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Thank you for explaining this. I have actually been curious about this bootleg ground concept. When I opened the panel I expected to find SER cable, so this helps explain what could have been going on.
Was the unit wired using metallic conduit? If so it would be the ground.
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Interesting. I’m not sure. Most areas were not accessible, but I’ll certainly look for this in the future
I’m going to guess metallic conduit was in play here and acting as the EGC.
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Could be. However, I was thinking in 1918 the original cabling was most likely to be knob & tube. The units were likely rewired somewhere mid-century. Putting in armored cable would have been significantly more expensive versus any NM cable that was available at the time, but certainly possible.
Yeah, hard to say. Just not enough info here.
In the panel below, I see only one circuit that has an EGC. If all of these circuits test out as grounded, the next thing I would look for is metallic conduit. If that is not present, start thinking about a false ground.
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Here is one piece of armor. Which should not be outside 
Agree. It looks like THWN or THHN. Which was pulled through something
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Gotcha. I think I would do the same in this situation.
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That appears to be the GEC in what could be cable armor. Cable armor is permitted in wet locations when protected by a coating such as when it is galvanized.
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Thanks for the clarification. My understanding was it needed to be PVC jacket.
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Here’s a few code sections regarding Cable Armor and product link.
AFC Cable systems Armored Ground Cable, Reel Packaging, 1 Conductor, Bare Solid Copper Conductor, 8 AWG Conductor, 0.47 In OD, 1000 ft Length, InterLocked Galvanized Steel Strip Jacket
300.6 Protection Against Corrosion and Deterioration.
Raceways, cable trays, cablebus, auxiliary gutters, cable armor, boxes, cable sheathing, cabinets, elbows, couplings, fittings, supports, and support hardware shall be of materials suitable for the environment in which they are to be installed.
300.6(A) Ferrous Metal Equipment.
Ferrous metal raceways, cable trays, cablebus, auxiliary gutters, cable armor, boxes, cable sheathing, cabinets, metal elbows, couplings, nipples, fittings, supports, and support hardware shall be suitably protected against corrosion inside and outside (except threads at joints) by a coating of approved corrosion-resistant material. Where corrosion protection is necessary and the conduit is threaded in the field, the threads shall be coated with an approved electrically conductive, corrosion-resistant compound. Informational Note: Field-cut threads are those threads that are cut in conduit, elbows, or nipples anywhere other than at the factory where the product is listed. Exception: Stainless steel shall not be required to have protective coatings.
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Most appliances that I buy these days have two-prong plugs.
Obviously, ungrounded 3-prong outlets are an issue. There is often reason to be suspicious of 3-prong outlets that show grounded with a 3-light tester in pre-60 buildings and I will try to confirm if there are bootleg grounds.
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Probably not. It was likely wired as a three-wire system. Four-wire systems are a relatively recent thing.
That’s a faulty assumption. The fact that it is a three-wire system does not mean that it is likely that there are no grounded receptacles. Receptacles with an equipment ground connection were the standard for half a century with three-wire systems.
There may be metal conduits feeding the outlets or there may be metal conduits feeding junction boxes which in turn feed the outlets with NM cable, AC cable, et cetera.
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