What does a zero ohm reading indicate if measured across a switch?

A zero ohm reading measured across a switch indicates that there is continuity, which means that the switch is closed. In this state, electricity can flow through the switch, and the low resistance reading reflects that there is no obstruction to the electrical current. This is an important concept in HVAC systems and electrical circuits, as identifying whether a switch is open or closed helps determine the operational status of different components within the system.

When a switch is functioning correctly and is in the closed position, the expected resistance is near zero because the conductive path is complete. Such readings are crucial for troubleshooting, as they provide clear information about the electrical state of the switch and can help determine if power is being directed to necessary components, like a motor or a heating element, within the HVAC system.

In contrast, if the switch were open, a high resistance or infinite reading would be indicated, meaning that no current can flow. Understanding these readings is fundamental when diagnosing issues in HVAC equipment to ensure safe and efficient operation.