Electronics > Repair
Question about voltage in U.S. house built in 1890
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Stray Electron:
   Is that your main breaker panel or is it a sub-panel??????????????


  In the 3rd and 4th pictures in post #13 you can see the Ground bus bar on the LH side of the box and there's nothing connected to it. It's mounted directly on the metal box so the box should be directly connected to Ground. That is IF the Ground wire was connected to the Ground Bus Bar, but from what I can tell nothing is connected to that bus bar.  The Neutral bus bar is on the RH of the box and is visible in photos 3, 4 and 5. Note that it is insulated from the metal box.

  If your house was wired to modern standards ALL of the ground contacts in ALL of your outlets should run directly back to that Ground Bus Bar and if it is your Main Panel then the bare ground wire that connects to your Ground Rod should also connect to it.

   The wire that you point out in photos 1 and 2 appears to be a ground wire but it's attached to a different box than that shown in photos 3, 4 and 5.  It's been painted over but it should a bare, solid copper wire and it should be clamped to a ground rod but some people merely shove them into the ground. You need to dig into the soil and see what's there.

  A agree with a previous poster, even though you have a three contact outlet I don't think that the ground contact in it is actually connected and the voltage that you're seeing from L1 to Ground is just from leakage. 
Stray Electron:

--- Quote from: bdunham7 on May 14, 2024, 03:24:36 pm ---Can you take a zoomed-out photo so we can see the entire installation including the other boxes nearby?  I'm not seeing any ground wires in the box.  The bus bar where the white wires are going to should be the neutral/ground bond.  There's one big black wire going to that bar at the top, where does that come from?

Also, this looks like a sub-panel, not a main service panel.  There's no main breaker.  Is there any other sort of accessible panel anywhere?  Where does the service entrance come from--overhead or underground?

--- End quote ---


  I agree, it looks like a sub panel.  You can follow the feed wires out through the hole in the lower left side of the box and in photo #1 you can see that that conduit feeds back to box #2.  The OP's "ground wire"? in photos 1 and 2 also goes into box #2.  But based just of these photos it's impossible tell if it's connected to anything.

   BTW not all houses in the US have a 'Main Breaker". Mine doesn't.  The incoming power lines directly feed the L1 and L2 bus bars.

    OP I will point out that unless a previous owner did some weird and illegal trickery somewhere in the wiring after it leaves the box, then none of the circuits coming from box #3 are grounded.  You can follow every wire in that box and and they all connect to the 3 incoming power lines or to the Neutral Bus Bar or to a circuit breaker so there are NO Ground wires anywhere on those circuits.
niemand:

--- Quote from: bdunham7 on May 14, 2024, 02:04:57 pm ---[...]
With the voltage readings you are seeing, I would expect all 3 lights to be on at least dimly.  Try measuring from the ground of your socket to a plumbing pipe.

--- End quote ---
The ground I have been using for this comes from this 4-outlet type receptacle that is being used by computers:

This is located right on the other side of the wall where the service panel is. All the original readings came from the bottom right outlet of this receptacle. The black plug on the upper left is an APC UPS system (Smart-UPS 1000) for computers and router. I don't have an extension long enough to reach plumbing pipe from here. (Behind the wall in the back is the kitchen where a 2-outlet receptacle is being used by the refrigerator and stove. I've been presuming that this is wired to the same ground as the 4-outlet one being used by the computers.)

Per your advice to get a reading from a plumbing pipe, I had to use the 2-receptacle GFCI outlet located in the bathroom, which is on the opposite end of the dwelling unit:

I used the ground slot from this with the black probe and got the correct 122 V when I inserted the red probe into the hot (narrow) slot on the ancient 2-slot outlet out in the hallway (the hot slot of both 2-slot outlets gave me 122 V; the neutral slots gave me 0 V). Touching the plumbing pipe with the red probe gave me 0.009 V; lifting away the probe gave me 5 V (perhaps due to capacitative coupling?). So it appears that this receptacle is properly grounded, whereas the 4-outlet receptacle being used by the computers is questionable.
niemand:

--- Quote from: bdunham7 on May 14, 2024, 03:24:36 pm ---Can you take a zoomed-out photo so we can see the entire installation including the other boxes nearby?  I'm not seeing any ground wires in the box.  The bus bar where the white wires are going to should be the neutral/ground bond.  There's one big black wire going to that bar at the top, where does that come from?

Also, this looks like a sub-panel, not a main service panel.  There's no main breaker.  Is there any other sort of accessible panel anywhere?  Where does the service entrance come from--overhead or underground?

--- End quote ---
I don't know how to tell a main from a sub panel.
Service entrance? Perhaps behind the wall? The 4-outlet receptacle I mentioned above is behind this wall about 5 ft to the right.

Other boxes nearby:



Main service panel perhaps (I can't open the long one with the wing nuts at the bottom of it):




bdunham7:
Is this a townhome and the other meter is for the other owner/tenant?  Those are two "main breakers" under the meters so that all makes sense, but there are still no ground wires anywhere so I've no idea how your outlets are getting grounded.  That big, painted wire going into the ground probably goes to a ground rod of sorts and perhaps the wire going back into the house is cobbled into some sort of ground wire network going to the outlets, but that would be pretty hacked work.  The only other possibility I can think of is that your house has conduit throughout and the ground bonding goes through that.  I don't see any NM sheathed wires, so perhaps that is what they did, in which case you can pull the covers off your outlets and you should find a metal box that is grounded.  Your bad ground at your 4-plex outlet could be due to a break in the conduit or a bad ground bond between the box and outlet ground terminal.
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