Here are a few scenarios where "COM" might be used in electrical wiring diagrams:
1. Light Switches: In a light switch wiring diagram, "COM" may refer to the common terminal of a single-pole, single-throw (SPST) switch. This terminal is connected to the power source and is shared by both the "ON" and "OFF" positions of the switch. When the switch is in the "ON" position, the COM terminal is connected to the load (e.g., a light fixture), completing the circuit and allowing the light to turn on.
2. Relays: In a relay circuit, "COM" may represent the common terminal of the relay. This terminal is usually connected to the power source and serves as the shared connection point for the normally open (NO) and normally closed (NC) contacts. Depending on the energization or de-energization of the relay coil, the COM terminal will connect to either the NO or NC contact, completing or breaking the circuit.
3. Thermostat Wiring: In a thermostat wiring diagram, "COM" may indicate the common terminal of the thermostat. It is the connection point where multiple wires from different sensors and components converge. The COM terminal provides a common reference point for the thermostat to receive signals and control heating or cooling systems.
4. Audio Systems: In an audio amplifier or speaker wiring diagram, "COM" might denote the common ground point. It is the reference point for the audio signals and is shared by multiple components to ensure a consistent electrical potential and minimize noise.
It's important to note that the specific meaning of "COM" may vary depending on the context and the specific electrical system or device. Always consult the manufacturer's documentation or the specific wiring diagram to understand the exact function and connections associated with the "COM" terminal in a given application.
