If a three-wire capacitive sensor has two terminals connected to the power supply, what should be connected to the output terminal?

• A. Controller input terminal
• B. Ground
• C. Neutral
• D. Live supply

Answer: (A)

The output wire on a three-wire capacitive sensor is the switched signal that feeds the controller. With two wires already powered, the remaining wire is meant to connect to the controller’s input so the controller can read the sensor’s state. The sensor’s internal switch drives this output based on detection, and the controller input is designed to sense that signal (often with its own pull-up or pull-down as needed). Connecting the output to ground or to live/neutral would bypass the intended signal or create an improper path, so the correct connection is to the controller input.