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Siemens LGB2B125B Molded Case Circuit Breaker
- 125A
- 2 Pole
- Bolt-On
Siemens
LGB2B125B
Molded Case Circuit Breaker
Brand
Siemens
SKU
LGB2B125B
Quantity
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Siemens LGB2B125B - 125A 2 Pole Molded Case Circuit Breaker
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Description
Built for industrial power distribution, the Siemens LGB2B125B delivers thermal-magnetic protection in a 2-pole configuration. It provides dependable long-time and instantaneous trip functions for commercial facilities. The breaker installs into Siemens P1, P2, and P3 panelboards. It is officially replaced by the 3VA5112-6EC21-0AA0, which requires an additional mounting strap kit for proper integration. Equipped with load side lugs only, it achieves a 65kAIC rating at 480Y/277V.Specifications
| Brand | Siemens |
|---|---|
| Series | LGB |
| Amperage | 125A |
| Poles | 2 |
| Mounting Style | Bolt-On |
| Voltage | 240VAC, 480Y/277VAC, 600Y/347VAC, 125/250VDC |
| Phase | 1 |
| AIC Rating | 100kA @ 240VAC, 65kA @ 480Y/277VAC, 14kA @ 600Y/347VAC, 14kA @ 125/250VDC |
| Frame Type | LGB |
|---|---|
| Terminal Type | Lugs |
| For Use With | Siemens P1, P2, P3 Panelboards |
| Wire Gauge | 8-1/0 AWG (Cu), 8-2/0 AWG (Al) |
| Max Wire | 1/0 AWG (Cu), 2/0 AWG (Al) |
| Min Wire | 8 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed Thermal, Fixed Magnetic |
| Available Options | Shunt Trip, Auxiliary Switch, Alarm Switch, Padlock Attachment |
|---|---|
| Accessories | Load Side Lugs |
| Standards | CSA C22.2 No. 5, IEC 60947-2, UL 489 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, Reverse Feed, Non-Interchangeable Trip, Quick-Make/Quick-Break, Trip-Free Mechanism, Common Trip |
Product FAQs
7 answersWhat panelboards are compatible with the Siemens LGB2B125B?
This bolt-on breaker is designed for use in Siemens P1, P2, and P3 series panelboards that are configured for xGB frame breakers. Note that panelboard branch spaces are typically configured for either BL/BQD frames or xGB/3VA41 frames, so verify your panel interior accepts the LGB frame.
How does the LGB frame compare to NGB and HGB breakers?
The LGB, NGB, and HGB breakers share the same physical xGB frame size and mount in the same panelboard spaces. The difference is their interrupting capacity. The LGB offers the highest interrupting rating in this family, providing up to 100kA at 240V and 65kA at 480/277V.
What does the LI trip function indicate on this breaker?
The LI designation indicates a thermal-magnetic trip unit providing Long-Time (thermal) overload protection and Instantaneous (magnetic) short-circuit protection. Both the thermal and magnetic trip points are fixed on this model.
Is the LGB2B125B rated for direct current (DC) systems?
Yes, this breaker carries a DC interrupting rating of 14kA at 125/250VDC, making it suitable for specific direct current applications alongside its standard AC ratings.
How does the LGB2B125B connect to the panelboard bus?
It features a bolt-on connection style, meaning it secures directly to the panelboard busbars with screws or bolts rather than snapping into place. Ensure the panel is de-energized before installation.
Does the LGB2B125B accept aluminum wiring?
Yes, the factory lugs are rated for both copper and aluminum conductors. They accept 8 AWG to 1/0 AWG copper wire, or 8 AWG to 2/0 AWG aluminum wire.
Can this breaker be installed while the panelboard is energized?
No. Because this is a bolt-on breaker that requires physically screwing the terminals to the busbars, the panelboard must be completely de-energized before installation to prevent arc flash and shock hazards.
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