Running a neutral wire from an outlet to a switch

In a house that was built in 1908 and rewired in the 70s…

The outlets have black (hot), white (neutral), and bare (ground). The switches have black, white, and bare, but the white is not neutral because it is just used to complete the circuit. The actual neutral may be at the fixture or in a junction box somewhere. Am I correct?

You can run a neutral wire from an outlet to a switch to make it z wave compatible as long as its on the same circuit. This should be done with Romex with the black snipped off. Am I correct?


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First I am not an electrician. That being said. Colors don’t matter to what they are. Sounds like your black is probably your hot from the panel and the white is the wire going to fixture. Meaning you don’t have a neutral. If your not sure I highly hire an electrician and have them install 1 switch for you. While they are there nick their brain and ask lots of questions to determine if the rest of the switches you want to install are within your capabilities

I’m not an electrician either but you can run the neutral from the outlet to the switches and use that neutral for the ST compatible switches. It doesn’t have to be from the same circuit for it to work properly (although a thoughtful electrician might run two circuits on a single neutral on opposite phases of the panel to zero out the current on the neutral).

I agree with gopack2, the colors are meaningless although technically if using white or green or grey as a “hot” conductor it should be taped with black or colored electrical tape to identify it. This isn’t always done. It seems you have correctly deduced that the “white” at your switches" is actually a load conductor (or line conductor) and isn’t a neutral so good work there.

Regarding romex - if it is an interior wall and not in a garage you can use romex. You could snip the black wire off and use the neutral (or use the black but cover the exposed jacket in white tape per above). Personally I always cap off unused wires because one never knows if they will be useful in the future. If you “snip” it off you may not have access to it again and it’s a shame to lose that redundnacy.

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Just cap the extra wire and mark it “spare from outlet x”. Don’t just snip it off.

For adherence to electrical code, a return path wire (ie neutral or switch leg to dead end switch) must be in the same conduit or wire bundle as the incoming power. Do not run a neutral by itself from a receptacle to a light switch box. Run a new 3 wire Romex from light box to switch box instead. Running a neutral by itself from a different box is unsafe and not to code.

Alternately you could run both power and neutral from outlet to switch, and then switched power and neutral to the light, and cap off the other wires in the light box.

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I did exactly this and it worked out nicely. I was very lucky there was an outlet on the other side of the wall from the switch that was between the same two studs, and on the same circuit. Sometimes life deals you some pretty cards like that.

Hey everyone, this was a really good learning experience for me. Thank you for the information. The outlet is only about 18 inches from from the switch, so it wasn’t hard.

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Most people are not aware of the recent change in the NEC 2017 code in 404.2© where the ground conductor can extend to the neutral. But only for these smart switches. And no more than 5 of these on a circuit.

404.2© Switches Controlling Lighting Loads.

The grounded circuit conductor for the controlled lighting circuit shall be installed at the location where switches control lighting loads that are supplied by a grounded general-purpose branch circuit serving bathrooms, hallways, stairways, or rooms suitable for human habitation or occupancy as defined in the applicable building code. Where multiple switch locations control the same lighting load such that the entire floor area of the room or space is visible from the single or combined switch locations, the grounded circuit conductor shall only be required at one location. A grounded conductor shall not be required to be installed at lighting switch locations under any of the following conditions:

(1) Where conductors enter the box enclosing the switch through a raceway, provided that the raceway is large enough for all contained conductors, including a grounded conductor

(2) Where the box enclosing the switch is accessible for the installation of an additional or replacement cable without removing finish materials

(3) Where snap switches with integral enclosures comply with 300.15(E)

(4) Where lighting in the area is controlled by automatic means

(5) Where a switch controls a receptacle load.

The grounded conductor shall be extended to any switch location as necessary and shall be connected to switching devices that require line-to-neutral voltage to operate the electronics of the switch in the standby mode and shall meet the requirements of 404.22.

Exception: The connection requirement shall become effective on January 1, 2020. It shall not apply to replacement or retrofit switches installed in locations prior to local adoption of 404.2© and where the grounded conductor cannot be extended without removing finish materials. The number of electronic lighting control switches on a branch circuit shall not exceed five, and the number connected to any feeder on the load side of a system or main bonding jumper shall not exceed 25. For the purpose of this exception, a neutral busbar, in compliance with 200.2(B) and to which a main or system bonding jumper is connected shall not be limited as to the number of electronic lighting control switches connected.

Officially you have to hook the black in the Romex to the hot of the same circuit, as it needs to have a counter balancing wire to the neutral. There is EMF created by the voltage imbalance carried by the neutral, and the neutral can get hot. So having the hot connected balances the circuit.

Yes the new code works, but not for all areas of the country. Your local code supersedes the NEC code. In my area, my local code still want grounds at all locations.

Just to be clear. You cannot substitute the ground for neutral and the changed to that section just means you don’t need to run the ground to those locations you mentioned but only if your house has raceway or be able to run the ground later without removing drywall and such. The code will be change again in 2020 which you will need neutral at all locations so homeowners won’t have this issue and substitute the ground for neutral.

That is correct. The code is really specific. You can’t just be lazy.

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