Why low voltage (40 Volts) at outlet

[ktnwin]

First, I have to apologize for the following really long description. I guess if I draw a diagram, most of the text below will disappear. I will draw diagrams to attach to this topic.

I need advise on this situation (40 Volts at outlet).

When I plug Xmas light in one outlet near the patio door of my living room, the lights do not lit up.
Plugging into a different one , Xmas lights lit up. All outlets in my living room are on same circuit, same breaker. I knew this when I replace all the (40 yrs) old receptacles with new ones and verify all are done properly with 3 prong receptacle tester.
The problematic outlet is NOT on the same circuit,, only get 40 Volts between hot and neutral.
The outlet is near the floor and above it at shoulder level, there is a switch for outdoor light and this works. \I tracked and found the 40 Volts come from the box containing the switch.

I expect to see 3 Romex: an active Romex goes in to bring in electricity. The second Romex goes down to the outlet below. And the third Romex goes to the light outdoor. And the connection should be as below:
The active black should be connected to the black going to the outlet and connected to the switch, the second terminal of the switch is connected to black wire for the light, All the 3 white wires are connected together and so are the 3 ground wires. Pretty straight forward. Right ?

However, what I see is something very abnormal: there are actually 3 white wires connected together, 2 of them have been stripped off in the middle about 1 inch exposing bare copper, the intact one goes to the outlet below. The 4-th white wire goes to the outdoor light and is connected to the black wire going to the outlet below !!! This wire also goes into a terminal of the switch, the other terminal is connected to the black wire going to the light outdoor.

Sorry for the long long description.

OK, I went ahead to take a picture of the connection and disconnect ALL at the switch box.
To my surprise, no wire carry electricity EXCEPT the white wire that goes to (or comes from) the light outdoor. I measure the voltage of this white wire to the other 3, I got 40 volts. That how the outlet below gets 40 Volts.

I have searched the Internet and many people have this same issue, but no one seems to have a solution. All just described the problem briefly.

I greatly appreciate any help I could get. (pictures will be added)

 

[Maji236]

Hi Lucian,

I totally agree with you on this outlet that has no neutral.
Connecting neutral to ground is only done at the main panel, and not allowed in any other place.

I will remove the receptacle and put a blank cover on this outlet. The ROMEX cable from the switch box above to this outlet box is not connected to anything at present time. Can I leave it this way or must do something about this cable ?

Ideally, I could remove this cable, remove the outlet box, do some drywall work to patch up the outlet opening then paint it. This is much more work but still within my DIY abilities.

I have removed more than a dozen low power devices embedded in the walls (Radio , Intercom, Alarm systems, their power adapters, alarm sensors) of this home and patched up the wall openings when my home went thru completely remodeling / painting, etc ... 9 months ago. Those are state of the art 40 years ago and now become state of the lost art.

Just putting a blank on it will suffice.

Back in the day (10 years ago or so) the US electrical codebook (NEC) started requiring a neutral to be brought to switchboxes. Until then, we usually didn't.

 

[Megawatt]

I think what you have now is a functioning circuit that is still potentially dangerous and not code-compliant. As I understand it, the original outlet in question is running its neutral current down the ground wire of the cable to the nearby light, which is now going across your link to the other light and some unspecified route of ground wires back to the panel.

Could @Megawatt, @Maji236 or someone US-based please comment?

@Lucien all I told the OP to try and combine the neutral to the ground wire just as a test ONLY to see if it started working. By no means did I think he would leave it like that

 

[Megawatt]

Just putting a blank on it will suffice.

Back in the day (10 years ago or so) the US electrical codebook (NEC) started requiring a neutral to be brought to switchboxes. Until then, we usually didn't.

Install wire nuts on each wire for safety and install a blank cover on it

 

[Lucien Nunes]

all I told the OP to try and combine the neutral to the ground wire just as a test ONLY

I didn't mean that was your suggestion. There was no neutral from the beginning, the outlet was already using the ground wire as neutral, and we had already proven that the connection was broken. I was curious as to whether a combined neutral/ground conductor had ever been acceptable to the NEC for grounding ordinary outlet circuits in domestic wiring, excluding known special situations such as the 10-30 dryer outlet.

 

[Megawatt]

I didn't mean that was your suggestion. There was no neutral from the beginning, the outlet was already using the ground wire as neutral, and we had already proven that the connection was broken. I was curious as to whether a combined neutral/ground conductor had ever been acceptable to the NEC for grounding ordinary outlet circuits in domestic wiring, excluding known special situations such as the 10-30 dryer outlet.

@Lucien you nailed it and yes at one time the grounding conductor was always used on dryers, and stoves. Of course now if you work on a house you have to pull new wire to them 2 appliances only if they buy new ones. I was under a house one day and was installing new wire for a stove they had bought and after disconnecting the wires and cut what I was thought was the stoves old cable with my ratchet cutters and POP, I had cut the dryer cable. He got his dryer rewired for free. ?

 

[DrPossum]

Gentlemen, thank you for this riveting post. I read every response and was at the edge of my seat working through it post by post with yall

 

[DrPossum]

I registered just to say that lol