Edit - Solved. Thank you @Harper - Reinstate Monica! A light connected to the same breaker was wired incorrectly upstream from the problem receptacle.

I think I might be a little over my head trying to DIY some electrical work in my 60's home. I am trying to replace my old 2 prong receptacles with GFCI protected receptacles following this Sparky Channel video https://www.youtube.com/watch?v=16KObgI44UE. To find the most upstream receptacle in the circuit, I removed all the receptacles (7 on this breaker, also 3 lights), capped all the wires, then tested with a non contact tester to see which line was still hot.

Oddly enough, 3 of the boxes still had hot black wires. 3 of the boxes also have no load wires (so only 1 set of black and white wires) and in one of those boxes both white and black wires are hot. There are only 2 wires in this box and both of them are hot. How?

I tested again with a (cheap) multimeter and got 120v from black to the metal box and also got 120v from white to the metal box. I am not knowledgeable at all about how to use a multimeter so not sure if that proves anything. The old receptacle was wired normally (white to neutral, black to hot) and did not work for as long as I can remember.

I plan on hiring an electrician eventually to take a look at this but unfortunately I cannot afford it at the moment. In the meantime, I plan on capping the 2 wires and covering it with a blank wall plate. Pretty curious as to how this happens. Greatly appreciate any enlightenment!


Wait, are they metal boxes? Are the wires in conduit or AC cable? The conduit/cable is a valid ground path.

Your neutral is that way because neutral is disconnected somewhere between this point and your panel. Somewhere on this side of it, you have a load plugged in, and it's pulling the voltage up toward 120V.

  • Wow, thanks for the info. I did not think to check the cables. Yes, the boxes are metal and yes the original wires are in flexible metal conduit. I just assumed no ground wire = no ground. I'll check the wiring again to see if there are any issues. Could be one of the lights. Appreciate the response! – user116503 Apr 29 '20 at 14:13
  • Checked the light downstairs (closest to the breaker box). Fairly positive this is where the problem is coming from. It has 5 sets of wires. I assume 1 from breaker, 3 branches to the room above, and one to the switch. It is wired beyond my capability to figure out. 3 whites capped together with 1 black. 4 blacks connecting to the black from the light fixture and the 2 remaining whites connected to the white from the light fixture. Glad to at least know where the issue with the receptacle stems from at least. Thanks for pointing me in the right direction. – user116503 Apr 29 '20 at 17:46
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    @user116503 Good. Pull stuff back, take some good photos, and ask another question.... also don't overlook the neutral bar in the service panel, that's a top place for trouble and nobody thinks about it... – Harper - Reinstate Monica Apr 29 '20 at 17:51
  • I isolated all the lines and was able to find the hot black coming from the breaker. Then I checked each black line with the hot line to see where they led to downstream. Capped all the white lines together except for the white from the switch and included a pigtail. Connected the light - white to pigtail, black to the white (now taped black) from the switch. I am pretty sure this is correct? The white line in the problem receptacle is neutral again and everything is working. Kind of amazed the light worked the way it was previously wired.Learned a lot. Hope I didn't miss anything. Thank you! – user116503 Apr 29 '20 at 20:42

When wires run parallel the hot can induce a voltage on the non energized wire. Put your meter on voltage and measure the potential from the black wire to the white wire as long as you have 120v you have a hot and a neutral. Connect up the GFCI with the black wire on the gold screw and the white wire on the neutral (both on the load side of the GFCI) turn the breaker back on press the test and reset and when the GFCI receptacle works all is well. You will need to identify the breaker for each chain of receptacles and sometimes you may find a chain branching 2 or 3 directions , in these cases a GFCI breaker in the panel will work for them all or one at the start of each break out. Don’t put multiple GFCI’s in 1 chain or a GFCI feeding another GFCI even if there are a few outlets in between 1 is all that is needed 2 may become difficult to reset and cause more false trips.

  • I tried black to white and did not get 120v (seemed to be jumping around the <1 range). Going to check to see if there is a disconnected neutral somewhere. Thank you for the advice on the GFCI installation. I wasn't expecting the multiple branches. – user116503 Apr 29 '20 at 14:54

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