I’ve recently guided an electrician on the wiring required for Z-Wave wall switch. Before successfully installing the Z-Wave switch, he actually used a neutral wire from some other part of the house and it caused a power trip. So, I invited him to my place to look at the wiring as reference and he eventually managed to install the switches successfully.
In this short article, I’d like to take this opportunity to show you how a normal light switch is being wired and how you should ask your electrician to lay neutral wire to the light switch. I’d also take the chance to explain why Z-Wave light switches require neutral wire. (Disclaimer: I am not an electrician nor have a degree in electrical engineering but my explanation is based on logic, research and some basic electrical knowledge from secondary school.)
Wiring for Conventional Light Switch
Wiring for Z-Wave Switches
Closed circuit in off state
Closed circuit in on state
For Z-Wave switch, in off state, the neutral wire keeps the circuit closed to power the switch module. This is the reason a neutral is required for Z-Wave switches.
Wiring for Conventional Dimmer
Wiring for Z-Wave Dimmer (on or off state)
For Z-Wave dimmers, in the off state, the circuit is always closed and a small current is always running through the lights to power the dimmer module, except that the current is not sufficient to light up the bulb. This is the reason a neutral wire is not required for Z-Wave dimmers.
I hope you will be able to use the above information to guide your electrician who is not versed in installing Z-Wave switches.