The Siemens 3RT1054-1LA06 is a SIRIUS power contactor in size S6, rated for switching motor loads up to 124 A at 480 V (AC-3 duty). The contactor also carries a 25 hp rating at 230 V, giving a quick cross-check for North American panel specs. Mechanical life is listed at 10,000,000 operations typical, with an AC-3 switching rate up to 1,000 cycles per hour. That means it's built for continuous-duty panels where the contactor cycles several times a minute — not just a start-stop once a shift. The auxiliary switch (included) handles pilot-duty loads: 10 A at 24 V, 2 A at 48/60 V, 1 A at 110 V, 0.9 A at 125 V, 0.3 A at 220 V, 3 A at 400 V, 1.4 A at 440 V, 2 A at 500 V.
Fastening is screw fixing (not DIN rail), so plan for a drilled backplate or mounting channel. Those are minimum air gaps for arc containment and heat dissipation; crowding them shortens contact life. Main power terminals accept stranded wire from 16 to 70 mm² — that's a heavy cable range, consistent with the 124 A rating. The coil terminals are screw-type, and the auxiliary terminals accept solid or stranded: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), max 2x (0.75 to 4 mm²). Strip and torque per the nameplate; the spring-cage variants in the same family use a different termination feel.
Operating conditions
Switching frequency varies by duty: AC-1 max 800 cycles/h, AC-2 max 400, AC-3 max 1,000, AC-4 max 130.