The LADN31A is an auxiliary contact block from the TeSys Deca range, designed to snap onto the front of a contactor or reversing starter to add extra control-circuit signalling or interlocking contacts. It provides three normally-open and one normally-closed instantaneous poles — a 3NO + 1NC configuration that covers most feedback and logic needs without requiring two separate blocks. Rated operational current depends on the duty: 6 A at 120 V AC-15 (typical for contactor coils and solenoid valves), 1.04 A at 690 V AC-15, and 0.55 A at 125 V DC-13 or 0.1 A at 600 V DC-13 for DC switching. The conventional free-air thermal current is 10 A at 60 °C, which sets the wiring and fuse limit — protect with a 10 A GG fuse per the spec. The block carries approvals to EN/IEC 60947-5-1, UL 60947-5-1, and CSA C22.2 No 60947-5-1, so it's accepted in North American and European control panels without extra qualification.
The 10 A thermal current (Ith) is the continuous current the block can carry in free air at 60 °C — this is the rating to use for bus-bar or common-feed wiring through the block, not the switching rating. For actual load switching, use the AC-15 or DC-13 values: at 120 V AC the block can switch 6 A of inductive load, enough for a bank of contactor coils; at 690 V AC the current drops to 1.04 A, reflecting the higher arc energy. Minimum switching capability is 5 mA at 17 V — below that, the contacts may not reliably wet the circuit. This matters for PLC digital inputs or dry-contact signals where the leakage current is very low. The block is not rated for electronic-level switching below those thresholds. It is intended for clean, dry panel environments, not washdown or outdoor locations. Operating altitude is rated to 3000 m (9842 ft) without derating; above that, air density reduction may affect dielectric withstand.
Front-mounting snaps directly onto the contactor or reversing starter without tools. The snap-in terminals accept 1 to 4 mm² flexible or rigid wire (with or without cable end), with two terminal positions per pole — one for the incoming wire, one for daisy-chaining to the next block. Terminal 1 accepts up to 4 mm², terminal 2 accepts up to 2.5 mm² with a cable end or 4 mm² without. Dimensions are compact: 44 mm wide, 42 mm deep, 48 mm tall — it adds minimal depth to the contactor footprint. The dark grey housing matches the TeSys Deca aesthetic and makes the block visually distinct from the main contactor body.