To determine if you have a Neutral, you must first disable the live circuit from your electrical junction box to your switch.
- For the load you are verifying - start with the light on and switch the circuit breaker or pull the fuse to ensure the load turns off.
- Note, just because the load is off, it is possible to have more than one live circuit in the box. Be certain power is removed to any adjoining loads in box.
- With power to the box turned off, unscrew and remove the wall plate and existing switch.
- DO NOT disconnect any wires.
Use the following as a guideline to determine if you have a Neutral. Installation should be performed by a professional electrician, not all structures are wired the same; therefore, results may be different than described below.
Power is delivered to the switch box or load over 3 conductors:
- Black – Hot
- White – Neutral
- Bare copper – Earth ground (may be missing in older homes)
If you have a Neutral:
- There must be at least two bundles coming into the box
- Bundles are often referred to as Romex or BX; multiple conductors in a single jacket
- There are two bundles coming into the box
- Whites are currently tied together
- One black wire is going to the pole on the existing switch and the other black wire is going to the second pole on the existing switch
If you don't have a Neutral:
- Only one bundle coming into the box
- One black wire is going to a pole on the existing switch and the white wire is going to the second pole on the existing switch.
- Unfortunately, even though you have a white, you do not have a Neutral.
- This wiring is known as a switched Hot. The Hot and Neutral from the electrical box was fed to the load first. The Hot was fed down to the switch box on black and returns to the load on white.
- To install Decora Smart Z-Wave device and stay within NEC code, a Neutral needs to be fed to the electrical switch box.
If additional information on determining if you have a neutral, view this video.