How should safety controls be wired in a circuit that includes operating controls?

Wiring safety controls in series with operating controls is a fundamental practice in electrical control systems, particularly in HVAC and refrigeration applications. This configuration is essential because it ensures that the safety controls can effectively interrupt the circuit in the event of unsafe conditions.

When safety controls are wired in series, they become part of the same circuit path as the operating controls. This means that if a safety control, such as a high-pressure switch or a temperature limit switch, detects a condition that may pose a risk to the system (like excessive pressure or temperature), it can break the circuit, shutting down the operation and preventing potential damage or hazards.

This setup guarantees that the operating controls cannot energize the equipment if the safety control is activated, ensuring a higher level of operational safety. In contrast, wiring safety controls in parallel would allow the operating controls to function independently of the safety controls, defeating their purpose and potentially leading to unsafe operation.

Overall, the series wiring method is crucial for maintaining safe and reliable function in HVAC systems, as it integrates safety mechanisms closely with the operational controls.