I've got an old house and an ungrounded cloth wired three way circuit with 2 lights and 2 switches.

At the top of my basement stairs is a switch tethered to another switch in the basement. This switch only has a neutral wire coming in and then down to the other switch in the basement and back up and out. From tracing the wire I know it goes down to a junction box in the basement ceiling. In this junction box the hot wire comes in and then hot and neutral connect to Romex that goes out to the 2 light fixtures.

I want to install a plug in my basement stairwell (other side from where the switch is) and this is the only circuit I can easily tap to do it. It's going to be for a dyson vacuum cleaner charger.

The problem is that the hot and neutral wires are in separate junction boxes about 5 feet apart. I can easily access them and run wires to the location where I want the plug but is there a reasonable/safe/to code way to do this? I could run Romex and only use 1 wire in each run but this seems like a code violation. Can't imagine it's that dangerous but wondering what the best way to do this is without replacing the antique wiring. The basement was finished at some point and I'm guessing this circuit was too much of a pain in the a$$ to update which is why it wasn't updated.

Any thoughts? Thanks in advance for the advice.

 

The switch that you are indicating a "neutral" is not a neutral. Always keep in mind, that not all white wires are neutrals. In your case the white wire you are pointing to is not a neutral. Where is the power coming in from? Is it at the ceiling junction box?

You would pick up the neutral in the same cable/romex that the hot is in. According to your diagram the hot is coming in at the light fixture box. This would be where you have to run your romex from to a new receptacle.

 

Your diagram has the 2 switches wired in series. This means both switches must be closed for the lights to be on and either switch opened will turn lights off. Is this the operation of your switches?

 

There are a variety of old (pre-1950) home wiring systems where neutral and hot run separately. For example leg A hot along the front, leg B along the back, and neutral through the middle.

There are also a variety of obsolete 3 way wiring diagrams that cannot be modernized without restringing all new wiring.

One such 3 way plan chooses hot or neutral from one source and chooses neutral or hot from another location (requires both hot and neutral along the front and both hot and neutral through the middle if those are the two respective switch locations). If both switches choose hot then the light is off. If one switch chooses not and the other chooses neutral then the light is on. At the light you see the "hot" and the "neutral" go singly in different directions. This is another example that requires stringing a lot of new cable to modernize.

Modern wiring requires that the hot and neutral follow each other. Except when going from a light only to a switch where you do not need two neutrals on the same path, one following the raw hot down to the switch and the other following the switched hot back to the light. Here only one neutral needs to tee off of a feed neutral entering at the light and go to the switch. Older unmodified installations with no neutral going down to the switch are grandfathered.

 

Switching neutral is a code violation today and hopefully back then because the load is still at a voltage even though any load indication is not lit with the switch open. Even back then there must have been plug fuses installed. What and where is the electrical protection for this circuit today?

 

Sounds like the existing is knob-and-tube (or a modified K&T). I believe current codes forbid modifications and extensions of K&T wiring.

 

Please double check your drawing - makes no sense. Please look at your wiring again.

Lights can't be working with your diagram as I don't see a neutral coming into the junction box in the basement; at least you have not labeled a neutral in that box I realize you said that the neutral is elsewhere. You can't run lights with just a hot wire but in the diagram you show neutrals connected to the lights but don't show where it is coming from.

Even if this is knob and tube (is it?) you have to have a neutral and hot at each light no matter what.

If the lights are presently working then you diagram is incorrect.

Double check your two switch boxes. Double check your light fixture box. Indicate correctly what the wires are and how they are connected.

 

Thanks for all the responses so far! For some reason I couldn't post yesterday I kept getting an error.

I've clarified the drawing as to what I think is happening.

I wired up a switch using neutral from the top of the stairs box and hot from the basement ceiling box. I turned the circuit back on and using my circuit tester it showed a constant 120v with open ground and a red fault light. When I turned the switches on and off it didn't affect the reading on the tester. I also used an extension cord from a different outlet/circuit and tested with my multimeter to confirm the hot and neutral. I'm pretty sure the diagram below is accurate.

Some other info is that the circuit is coming from an updated electrical box with proper romex and grounding. Somewhere in the walls is where this mess is happening.



If this is all true I think I have a few options:

• Leave this circuit as is. It might be grandfathered in.
• Update all the wiring (this might be hard and costly - not gonna do it myself as it might involve outlets on the first and second floor as well)
• Improve the existing wiring by running a HOT line from the basement ceiling junction box to the switch and change the wiring so HOT switches the lights instead of neutral. I have access to all these boxes so I could improve the existing wiring. This would definitely be safer afaik. It would allow me to then tap power from the switch to the outlet. The separate run of neutral and hot wires would still exist in the walls however I would be bringing the wires back together at the switch and then running them together throughout the rest of the circuit.
• Pull power from somewhere else
• Pull power from this circuit anyway as is. How dangerous can it be? Probably how it would have been done back in the day. There could be other outlets on this circuit already wired this way, I'm not 100% sure.

 

Something is still not correct.

Hot must go to one of the two 3 way switches to the "common" screw.
No "neutral" actually gets connected to either of the two 3 ways witches. *Note: if there is a white wire connected to either or both of the 3 way switches it is not a neutral.*
"Load" wire running to light must connect to the "common" screw of the other switch.

 

Really appreciate all the replies so far thanks for bearing with me as I try and figure this out. At this point, I'm more interested in how this works than anything.

AFJES Thanks for giving me more feedback. I'm very confused at this point.
AllanJ This seems like what you were describing.
beelzebob I think you are correct.

Attached is an image using my non-contact voltage tester at the switch, ceiling junction box, and one of the lights.




I'm confused by these readings. With the lights turned off every wire in the ceiling junction box, and one of the ceiling lights show voltage running through them - and in the switch, only the red wire shows it has voltage. With the lights turned on, no wire in the switch shows voltage running through it and only the black wires in the one light box and ceiling junction box show voltage.

Of note is that in one of the light boxes there is black tape over all 3 wire nuts. I know this to mean hot from a book I have and when the light is switched off the hot and neutral both appear to have voltage running through them.

Also in terms of wire colors, my drawing has the colors of the wires as they appear in the boxes, I just made a guess at the hot and neutral wires coming into the boxes but now I think that's wrong.

So here is my original image with the hot/neutral markings removed as I honestly have no idea which is which anymore and am just very confused about this circuit. The colors in this image are just as they are in the boxes.

Can anyone look at this diagram of wires in these boxes and make sense of this given all the wires in the ceiling junction box and at the light have voltage running through them when the lights are off, including the red wire in the switch, but when the lights are on, only the black wires show voltage and no wires in the switch show voltage?

 

Doing some more research maybe this is a "Carter 3-way" or a "California 3-way?"

On Wikipedia it says about the "Carter system"

"The major problem with this method is that in one of the four switch combinations the socket around the bulb is electrified at both of its terminals even though the bulb is not lit."

 

You need to identify the "common" screw in your diagram on each of the two 3 way switches. It should be a darker colored screw where as the other two are more silver. Make note in the diagram which wire is connected to the common screw. If there is not a darker colored screw then look on the back of the switches there may be either a "C" or "Common" imprinted on the back.

Non-contact testers are really not going to help you much here. They can pick up stray voltage and fool you. They/I use them just to see if a box has hot wires in them before I work on the box wires.

You need a meter. Suggest a analog (with dial and needle) not a digital.. Digital will pick up phantom voltage where analog will not. They are very cheap. Don't get a meter which just shows lights for 120 240 etc, get an actual meter.

Appreciate the photos but hard to determine what wires are connected to other wires in the boxes etc. Need clear photos. Be sure the power is off on this circuit (at the breaker) not just that the switches are turned off and pull the switches out so we can see the wires. Do the same on the junction box.

If we have clear photos to work with you may not need a meter at this time.

Any white wires that have tape on the ends by where the wire is stripped is indicating that that white wire is being used as a not wire and is not a neutral wire.

Do not disconnect any wires, just show good clear pictures of the boxes and wires.

 

Thanks for the feedback. My drawing is accurate. This circuit switches neutral. I ran a wire from the common on the switch and touched it to the neutral on the light and the light lit up. I also touched it to the hot and it arc flashed. I was able to run power from another circuit that's wired correctly and grounded. For now I'm gonna leave this poorly wired circuit alone.