[Electrical Help Needed] - No neutral in remote (3-way) box - odd wiring


Brand new to Smarthings - just got my setup yesterday. I’m normally pretty good with the DIY electrical, but this one has me stumped.

Originally had Eaton “smart” dimmers in a 3-way configuration on 3 separate sets of can lights (directions here. They worked perfectly as wired per the directions.

I am trying to install some GE Z-Wave dimmers (12724) and Add-on switches (12723) in the same locations and am running into a snag. I have neutrals in 2 of the boxes, but don’t in the third. (see pics below). I can’t seem to figure out the correct wiring to make this work.

Is the solution to run a neutral to the third box, or is there a way to eliminate the 3-way altogether (as I don’t really care about them - I can just blank the boxes off).

Thanks kindly in advance!



I made a quick diagram awhile back. It is here: https://community.smartthings.com/t/trouble-with-3-way-switch/38405/8

It really doesn’t matter which colors you use for what just make sure you know what they are. The proper way would be to use colored electrical tape to designate what colors they are.

The most confusing thing for people is trying to wrap their brain around how the new smart switches work vs old 3-way and 4-way setups.

Try to think of the Add-On switches not as a device that carries a LOAD (Light) / LINE (Power) but as a Toggle Switch that is triggering the Master Switch. All the magic happens inside the Master Switch. It carries the LOAD and it has the Relay inside of it that triggers the LINE to connect the LOAD.

All an Add-On switch does is sends a signal/command to tell the master switch to turn on/off. The master switch also is the device that has the Z-Wave or ZigBee wireless inside that talks to the Smartthings Hub. So to recap the Add-On switch is just a very simple device/switch and this is why they are ridiculously inexpensive when compared to the Master Switch.

The Master Switch needs to be located where the LOAD/LINE will be connected. You DO NOT want to have LOAD/LINE going to the Add-On switch. This will burn out your Master Switch and possibly the Add-On switch.

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Nice and clear pics but it would also help plenty if you could take the picture of the switches with the wires still attached. Include the wires on the C terminals of the switches. If possible, identify which wire goes to which romex. Since you have everything disconnected and you already know the neutral. Check for line hot and load if possible. You can use the bare wire to check for line hot if you are not sure about the neutral wire.

Edit : OK maybe it would be a pain to put back the old switches for pictures. Can you still remember the wires going to the C terminals of the 3 ways switches?


You need to identify power line and load line.
This should be the result (master is the leftmost). If you don’t need 3-way don’t use any slave.