Use this normally‑closed (NC) auxiliary when you need a control circuit that changes state the moment a contactor energizes - ideal for safety chains, interlocks, and “run/stop” logic that must fail safe. In practice, NC auxiliaries are often used to break a circuit when equipment starts (for example, disabling a second function, preventing simultaneous operation, or signaling a controller that a stage has engaged). It’s also useful for troubleshooting and service because it gives technicians a straightforward way to confirm control sequencing without probing high‑voltage conductors. This auxiliary is part of the new A2L‑compliant auxiliary switch range for compatible contactors. It’s also specifically called out internally as compatible with the larger A2L transition contactor family that accepts the 61598–61605 auxiliaries, making it a practical choice when standardizing parts during upgrades or replacements.