Siemens LGB3K125B Molded Case Circuit Breaker
- 125A
- 3 Pole
- Bolt-On
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Siemens LGB3K125B - 125A 3 Pole Molded Case Circuit Breaker
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Description
Part of the SENTRON family, the Siemens LGB3K125B is a 3-pole, 125A molded case circuit breaker engineered for commercial and industrial power distribution. It features fixed thermal and fixed magnetic trip units to provide dependable long-time and instantaneous (LI) protection. This bolt-on MCCB installs into Siemens P1, P2, and P3 panelboards. It accepts 8-1/0 AWG copper or 8-2/0 AWG aluminum wire via load-side lugs.Specifications
| Brand | Siemens |
|---|---|
| Series | LGB |
| Amperage | 125A |
| Poles | 3 |
| Mounting Style | Bolt-On |
| Voltage | 240VAC, 480Y/277VAC, 600Y/347VAC, 125/250VDC |
| Phase | 3 |
| AIC Rating | 100kA @ 240VAC, 65kA @ 480Y/277VAC, 25kA @ 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 |
|---|---|
| Accessories | Load Side Lugs |
| Standards | CSA C22.2 No. 5, UL 489 |
| Approval | CE, CSA, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, Reverse Feed |
Product FAQs
6 answersWhich Siemens panelboards are compatible with the LGB3K125B?
This bolt-on breaker is designed for use in Siemens P1, P2, and P3 panelboards.
What wire sizes and materials are supported by the terminals on this breaker?
The included lugs accept 8 to 1/0 AWG copper wire or 8 to 2/0 AWG aluminum wire.
Can the LGB3K125B be used in DC voltage systems?
Yes, this breaker is rated for DC applications up to 125/250VDC with a 14kA interrupting capacity.
What is the difference between Siemens LGB, NGB, and HGB breakers?
These breakers share the same physical GB frame and mounting dimensions but differ in their short circuit interrupting ratings. The LGB provides standard interrupting capacity, while the NGB and HGB models offer higher ratings.
Are the thermal and magnetic trip settings adjustable on the LGB3K125B?
No, this breaker features fixed thermal and fixed magnetic trip settings for its long-time and instantaneous (LI) protection functions.
Does this breaker provide ground fault or arc fault protection?
No, the LGB3K125B is a standard thermal magnetic breaker with long-time and instantaneous trip functions. It does not include GFCI or AFCI protection.
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Reviews
Review summary
Customers rate this product 5.0 out of 5 based on 1 review.
- RSRon S.Verified BuyerReviewingSiemens LGB3B045B - 45A 3 Pole Molded Case Circuit BreakerI recommend this productRated 5 out of 5 stars9/27/26Siemens Breaker
The breaker was exactly what I needed, and it came within a couple days. The price was in line of what it should’ve been. This was my third purchase from Super Breakers. I will definitely use them again in the future.