Old house, what is going on in this junction box?

[WallyWest]

I've done basic wiring, not a pro by any means. But I know enough to not electrocute myself, which is why I'm not touching this until I understand it. Pic below.

I want to replace that old black cable going from this box to an outlet over my workbench. It's the two wire, no ground type cable and everything else is modern. So just swap cables, replace the outlet with a grounded one, and we're good. Or so I thought. Then I saw that mess.

Here's where all those cables are going.

The black one, as I said is heading over to an outlet. That's it, end of the line.

The two cables coming in from the top of the box both go to the breaker box. One goes straight there, nothing else in between. This, I believe, is the line I'm actually working on. If I turn off the breaker my outlet goes dead. As expected.

But then it gets weird. The other cable also goes to the breaker box, but helpfully has a light outlet in the path. That cable, in the junction box pictured, I don't understand. The neutral wire is hanging, not connected to anything. The hot wire is spliced into the red wire heading out the left of the box. Ground is twisted together with all the other grounds.

The hot wire for the circuit I'm working on is twisted together with the hot from both the black cable and the cable going out the left of the box. Same for the neutral.

The cable going out the left of the box goes to another light socket, and then onto the other side of the basement, and ultimately up to my third floor for some reason. I know that because I have mapped out all the breakers and what they power.

If I turn the breaker that feeds the outlet I want to work on, at the other end of that black cable, it goes dead. The lights however, on both sides of the junction box stay on. I have to flip a different breaker to kill those lights. I took the twist caps off the main connections there, the two sticking down. If I kill the outlet and not the lights I get nothing on a multimeter when I check those wires. But the hot and neutral wire from the left cable, going to a light that is very much on, is twisted into those wires.

Anyone have the slightest idea what's going on here? The obvious answer is to kill both breakers, do what I need to do, and call it a day. But I'd also like to know if this is seriously messed up and I should be looking into it further. I don't understand the left cable. It's got four wires. The normal white, black, and green, and also a red that is spliced into the hot wire from the top that has a dangling neutral wire.

 

[James]

It is not easy to see or fully understand from the description.

However, it seems like you may have 2 circuits sharing the same cable.
In the uk this would be ok, as long as each circuit had its own neutral.
Not sure about the regs where you are.

 

[littlespark]

From this side of the pond, it looks as though someone has “borrowed” a neutral from another circuit.

I’m sure someone like @Megawatt will be able to tell.

 

[Dustydazzler]

Could it not be a 3 plate lighting box ?

 

[Mike Johnson]

I think Dusty has it, looks like a three way lighting box that someone has tapped into for a socket.

 

[Timbo]

What about the switch for the light? Where does that fit in to this circuit?

 

[Lucien Nunes]

The hot and neutral of your outlet circuit are both present in the cable to the left (black and white) along with the red switched hot returning to the light nearer the panel via the 3rd wirenut. But the switch is not taking its power from that black hot, because when you kill that breaker, the lights stay on. Another hot from the second breaker must arrive at the switch via a different route to power the lights.

If you ignore the red switched hot passing through the J-box to the light, everything seems normal, it's just power arriving straight from the panel and splitting to your outlet and the cable to the left. The light has its own neutral back to the panel, it's not sharing the neutral in this box as you point out the white wire is not connected. So far, there is no evidence that the two circuits are cross-connected in a way that would violate code. The pecularity is that the 4-wire cable contains hot and neutral of the outlet circuit heading away from the box, and a switched hot for the light circuit heading towards it. I am not sure if that is code-compliant if they are not part of one multi-wire branch circuit.

What would be interesting though, would be to look in the light between this box and the switch, and find out where it gets its neutral from. If it uses the neutral in this cable (which belongs to the outlet circuit) it's a cross-connection (aka borrowed neutral) and probably a violation. If a neutral belonging to the light circuit arrives from the direction of the switch or panel, again it could be OK.

Some pics of the light and switch would be revealing.

 

[Megawatt]

I've done basic wiring, not a pro by any means. But I know enough to not electrocute myself, which is why I'm not touching this until I understand it. Pic below.

I want to replace that old black cable going from this box to an outlet over my workbench. It's the two wire, no ground type cable and everything else is modern. So just swap cables, replace the outlet with a grounded one, and we're good. Or so I thought. Then I saw that mess.

Here's where all those cables are going.

The black one, as I said is heading over to an outlet. That's it, end of the line.

The two cables coming in from the top of the box both go to the breaker box. One goes straight there, nothing else in between. This, I believe, is the line I'm actually working on. If I turn off the breaker my outlet goes dead. As expected.

But then it gets weird. The other cable also goes to the breaker box, but helpfully has a light outlet in the path. That cable, in the junction box pictured, I don't understand. The neutral wire is hanging, not connected to anything. The hot wire is spliced into the red wire heading out the left of the box. Ground is twisted together with all the other grounds.

The hot wire for the circuit I'm working on is twisted together with the hot from both the black cable and the cable going out the left of the box. Same for the neutral.

The cable going out the left of the box goes to another light socket, and then onto the other side of the basement, and ultimately up to my third floor for some reason. I know that because I have mapped out all the breakers and what they power.

If I turn the breaker that feeds the outlet I want to work on, at the other end of that black cable, it goes dead. The lights however, on both sides of the junction box stay on. I have to flip a different breaker to kill those lights. I took the twist caps off the main connections there, the two sticking down. If I kill the outlet and not the lights I get nothing on a multimeter when I check those wires. But the hot and neutral wire from the left cable, going to a light that is very much on, is twisted into those wires.

Anyone have the slightest idea what's going on here? The obvious answer is to kill both breakers, do what I need to do, and call it a day. But I'd also like to know if this is seriously messed up and I should be looking into it further. I don't understand the left cable. It's got four wires. The normal white, black, and green, and also a red that is spliced into the hot wire from the top that has a dangling neutral wire.View attachment 63831

I've done basic wiring, not a pro by any means. But I know enough to not electrocute myself, which is why I'm not touching this until I understand it. Pic below.

I want to replace that old black cable going from this box to an outlet over my workbench. It's the two wire, no ground type cable and everything else is modern. So just swap cables, replace the outlet with a grounded one, and we're good. Or so I thought. Then I saw that mess.

Here's where all those cables are going.

The black one, as I said is heading over to an outlet. That's it, end of the line.

The two cables coming in from the top of the box both go to the breaker box. One goes straight there, nothing else in between. This, I believe, is the line I'm actually working on. If I turn off the breaker my outlet goes dead. As expected.

But then it gets weird. The other cable also goes to the breaker box, but helpfully has a light outlet in the path. That cable, in the junction box pictured, I don't understand. The neutral wire is hanging, not connected to anything. The hot wire is spliced into the red wire heading out the left of the box. Ground is twisted together with all the other grounds.

The hot wire for the circuit I'm working on is twisted together with the hot from both the black cable and the cable going out the left of the box. Same for the neutral.

The cable going out the left of the box goes to another light socket, and then onto the other side of the basement, and ultimately up to my third floor for some reason. I know that because I have mapped out all the breakers and what they power.

If I turn the breaker that feeds the outlet I want to work on, at the other end of that black cable, it goes dead. The lights however, on both sides of the junction box stay on. I have to flip a different breaker to kill those lights. I took the twist caps off the main connections there, the two sticking down. If I kill the outlet and not the lights I get nothing on a multimeter when I check those wires. But the hot and neutral wire from the left cable, going to a light that is very much on, is twisted into those wires.

Anyone have the slightest idea what's going on here? The obvious answer is to kill both breakers, do what I need to do, and call it a day. But I'd also like to know if this is seriously messed up and I should be looking into it further. I don't understand the left cable. It's got four wires. The normal white, black, and green, and also a red that is spliced into the hot wire from the top that has a dangling neutral wire.View attachment 63831

could you please separate all the wires and leave the wires nuts on them, also the grounds need a wire nut on them so they can’t separate

 

[Megawatt]

could you please separate all the wires and leave the wires nuts on them, also the grounds need a wire nut on them so they can’t separate

Send us a different picture with everything so we can trace all the wires

 

[Megawatt]

I've done basic wiring, not a pro by any means. But I know enough to not electrocute myself, which is why I'm not touching this until I understand it. Pic below.

I want to replace that old black cable going from this box to an outlet over my workbench. It's the two wire, no ground type cable and everything else is modern. So just swap cables, replace the outlet with a grounded one, and we're good. Or so I thought. Then I saw that mess.

Here's where all those cables are going.

The black one, as I said is heading over to an outlet. That's it, end of the line.

The two cables coming in from the top of the box both go to the breaker box. One goes straight there, nothing else in between. This, I believe, is the line I'm actually working on. If I turn off the breaker my outlet goes dead. As expected.

But then it gets weird. The other cable also goes to the breaker box, but helpfully has a light outlet in the path. That cable, in the junction box pictured, I don't understand. The neutral wire is hanging, not connected to anything. The hot wire is spliced into the red wire heading out the left of the box. Ground is twisted together with all the other grounds.

The hot wire for the circuit I'm working on is twisted together with the hot from both the black cable and the cable going out the left of the box. Same for the neutral.

The cable going out the left of the box goes to another light socket, and then onto the other side of the basement, and ultimately up to my third floor for some reason. I know that because I have mapped out all the breakers and what they power.

If I turn the breaker that feeds the outlet I want to work on, at the other end of that black cable, it goes dead. The lights however, on both sides of the junction box stay on. I have to flip a different breaker to kill those lights. I took the twist caps off the main connections there, the two sticking down. If I kill the outlet and not the lights I get nothing on a multimeter when I check those wires. But the hot and neutral wire from the left cable, going to a light that is very much on, is twisted into those wires.

Anyone have the slightest idea what's going on here? The obvious answer is to kill both breakers, do what I need to do, and call it a day. But I'd also like to know if this is seriously messed up and I should be looking into it further. I don't understand the left cable. It's got four wires. The normal white, black, and green, and also a red that is spliced into the hot wire from the top that has a dangling neutral wire.View attachment 63831

I need you to separate the black wire nut and the red so I can see exactly what is going on