30 A across-the-line block — 4 NC poles, 24 VAC coil
The ABB A16-04-00-81 is a 4-pole contactor rated 30 A at 440 V, with all four poles configured normally-closed (4NC). The 24 VAC 50/60 Hz coil pulls in the armature to open the NC contacts — so in its de-energized state the load circuit is closed, and powering the coil breaks the circuit. That makes it a fit for fail-safe or interlock schemes where the load must stay connected unless the control signal is actively present. Main power terminals accept 10–18 AWG; the auxiliary terminal range is 18–14 AWG. The contactor is rated for 690 V maximum across the poles, and the across-the-line block construction means no add-on aux contact blocks are fitted — the four poles are the full switching complement.
End-of-life sourcing — last-time-buy window
Because there is no direct pin-compatible successor from ABB, a panel originally built around the A16-04-00-81 will likely need a wiring review if you switch to a different contactor. The 4NC pole configuration and 24 VAC coil are the binding constraints for any substitute.