The 3RB1253-0FG00: Size S6 mounts on a busbar or individual base — continuous mounting or standalone. The main circuit is busbar-connected, so the relay sits in a power distribution bus rather than a dedicated contactor base. Auxiliary wiring is screw-terminal, which is field-friendly for a service tech: no special crimp tool, just a screwdriver. The control voltage is AC 110-120 V, common in North American panels and older European installations. If you're swapping one in a live panel, the busbar connection means you're pulling the whole Size S6 block — no shop, no crane, but you'll want the busbar dead before you break the connection.
Siemens 3RB1253-0FG00 Overload Relay, 50-205 A, Size S6
MPN3RB1253-0FG00
Siemens SIRIUS 3RB12 overload relay, Size S6, 50...205 A, discontinued product, busbar main circuit, screw terminal aux, AC 110-120 V 50/60 Hz.
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Jul 2026
Product details
Frequently asked questions
Where can I buy the 3RB1253-0FG00 and get a price?
This part is sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time — submit an RFQ and we'll check the surplus channel for you.
What is the adjustment range and trip class on the 3RB1253-0FG00?
It covers 50...205 A with an adjustable trip class from 5 to 30 F, so you can match the thermal characteristic to the motor's starting profile — slow for high-inertia loads, fast for standard starts.
MPN
3RB1253-0FG00