Tried searching for a solution but still having problems. I am currently trying to install a single zwave on off switch on a preexisting switch. However, it’s in a 2 gang next to a 3 way switch. Each control different lights. The current single pole switch i’m trying to replace doesn’t have a neutral. Should I be re-wiring it to make it work? I even tried to tie the neutrals together but it doesn’t seem to work. Any help would be appreciated.
Standard Electrical Disclaimer: Always work with circuit breaker off, and test for current before working. Safety is priority. Small details can have dangerous consequences, like wire nut size, wire gauge, and pig tailing limits. Be sure your work meets NEC electrical code standards.
Typically switches don’t require neutral connections. Current electrical code requires a neutral in the electrical box, but many homes were built before the recent code implementation. It’s important not to tie neutrals from separate circuits together. It’s possible the 3way switch is on a different circuit than the single pole switch in your situation. You can test by turning off the breaker to the box and see if one of the switches is still HOT. If both switches are on the same circuit, then you can pigtail into the neutral pigtail that already exists in the back of the electrical box right behind the switches. If there isn’t a neutral pigtail in the back of the box, you’ll need an electrician to pull a new romex.
It sounds like in your situation, there is a neutral in the switch box and you’ve pig-tailed the neutral from the smart switch with the existing neutral in the switch box. If that’s the case, and it’s still not working, you might have switched the line and load or have an open neutral (poor or loose pigtail).
Thanks for the response
I’ve attached a pic. There seems to be a neutral line but based on how it’s wired, the pre-existing single pole doesn’t have one. However, when I replaced the single with the zwave and piggyback the neutral to the existing 3 way, it throws off the zwave and will only work if 3 way is flipped on.
3-way switches do not use neutral. White wire is not necessarily a neutral.
Use multimeter to verify.
I also felt that way also but didn’t know how I should reconfigure the
wiring since the swap out from the single pole to the zwave requires a
neutral. That’s where I am now. Tried YouTube and Google searches without
success
looks to me like a possible 4-way switch setup and a single pole switch. There doesn’t appear to be a neutral in the switch box. Guessing here but it appears the white wire is the load to the 4way switched light fixture. Are there two other switches for that light fixture?
standard 3 and 4 way switches do not utilize a neutral wire. 
Just one switch. The single controls the side door light. The 3 way
controls the staircase leading down into the side door. Also down the
staircase is the other switch linked to the 3 way
3 ways can get tricky since there’s so many different combinations. With standard 3 way switches there is no neutral wired to the switch. So if you wire those two switches back to how they were before, it’s likely there will be no unused neutral wire capped in the back of the switch box. In which case you’ll need a neutral added to the box.
Tomorrow will be my first stab at doing a 3 way switch, hoping it goes half as well as the 2 single poles I did today…
1 Like
thanks. The thing I’ve run into in with my 2 switch replacements is the red in my house seems to run to load and not exclusively the traveler. It’ll be interesting to see what they use for traveler when I crack open my 3 way switches.
1 Like
Yeah for me finding where each wire actually runs is the hard part. Once I find which one actually goes to the light, the battle is over. Smart 3 ways are easier than standard 3 way switches imo Since the travelers are all connected to the main switch traveler out. All that traveling line hot stuff is confusing.
1 Like
The key to the puzzle is looking at your existing dumb 3way switches before you remove the wires. There is a black screw on them and one of them will have the load to the fixture and the other will have the line from breaker. The other wires, regardless of color will be travelers.
1 Like
Dumb question, but how do I id the line switch vs the load switch? I swear they both had line voltage on black wires. I have a dimmer on one of them and since it was closest to the light, I assumed it was the line switch. In the end, I had to cut my losses and returned to the original switches after they had been adequately cursed out.
Line switch has power when light is off; load does not
Each box in a circuit has a line from the panel, typically is 2-wire with the black bringing the power line in. The black from the 2 or 3-wire romex going to the light fixture is considered load. The switch just connects and disconnects the load and line. Smart switches use power 24/7 even when off so they require a neutral.
both the single pole switches I’ve replaced has red as the load, drives me nuts…
1 Like
Ugh. So the 2 gang box they used is on the small side, the corners are curved and not 90 degree square. Therefore there’s not enuf room for even 1 zwave switch.
Anyone know of a low profile zwave switch?
my switches are curved at the corners. Many smart switches have heat dissipation elements that are removable for multi gang boxes. Did you pry them off already?