A neutral wire is required to install a Brilliant Control. Normal electrical switches do not consume any power - they simply connect the power line to the light bulb. The Brilliant Control requires power, and power has to flow from the power line through the Brilliant, back out through the neutral. It needs a complete circuit to function. The neutral wire is usually the only white wire(s) inside your wall box. However, this is not always the case.
The first step to checking for your neutral wire is to turn off your circuit breaker for the switch you'd like to check.
Then, you'll need to unscrew your old switch from the wall. You can leave the wires attached to the screws on the switch.
Standard rocker and toggle switches will not have a neutral wire connected. If you do find a white wire connected to a rocker or toggle switch, it is likely not a neutral wire. You can check out our support article on common switches to help identify which wire this will be. You may have to pull the loose wires far out of the gangbox to see if you can find the white neutral wire.
If your switch is a dimmer, it may have a neutral wire connected. Look on your dimmer where the wires connect and on the wires themselves for labels that identify which wires go where. If you see an "N" or "neutral" - you can assume this is the neutral wire.
In some cases, the neutral wire will not be white (light gray is another common color) or may not be present at all. If you are unsure, it is best to call an electrician.
If you only have three types of wires in your wall box (red and/or black wires and copper or green wires), or if there is a white wire but it was connected to a rocker or toggle switch, then you likely do not have a neutral wire and cannot install a Brilliant without additional electrical work to add the neutral wire.