True or False: A reading of 24 volts across a limit switch indicates that it is open.

A reading of 24 volts across a limit switch indicates that it is open. When a limit switch is open, it is part of a series circuit where the voltage is present, but the current cannot flow through the switch because it is not making contact. The 24-volt reading comes from the voltage supplied by the control circuit confirming that the circuit is energized. If the switch were closed, you would typically see a different behavior, like a lower voltage reading or the voltage being present in a manner that indicates current flow through the circuit.

In HVAC systems, limit switches are safety devices that shut down the equipment when certain parameters are exceeded. A voltage reading across an open switch serves as a diagnostic tool, confirming the status of the switch. When troubleshooting, understanding that a voltage presence indicates an open condition is crucial for diagnosing issues and determining whether a limit switch needs to be replaced or if there's another problem in the control circuit.