Siemens KM3B300 Molded Case Circuit Breaker
- 300A
- 3 Pole
- Bolt-On
Quantity
Siemens KM3B300 - 300A 3 Pole Molded Case Circuit Breaker
Re-Certified
Quantity
Description
A reliable solution for power distribution, the Siemens KM3B300 is a 300A, 3-pole molded case circuit breaker. It offers fixed thermal and adjustable magnetic trip functions to safeguard commercial and industrial electrical infrastructure. This unit installs into Siemens P4, P5, S4, and S5 panelboards and SB series switchboards. When transitioning to newer equipment, the HJD63B300 serves as its replacement. Operating at up to 600VAC, it provides a 50kA interrupting capacity at 480V.Specifications
| Brand | Siemens |
|---|---|
| Part Number | KM3B300-R |
| Series | KM |
| Amperage | 300A |
| Poles | 3 |
| Mounting Style | Bolt-On |
| Voltage | 600VAC |
| Phase | 3 |
| AIC Rating | 65kA @ 240VAC, 50kA @ 480VAC, 22kA @ 600VAC |
| Frame Type | KM |
|---|---|
| Terminal Type | Lugs |
| For Use With | Siemens P4, P5, S4, S5 Panelboards, SB1, SB2, SB3 Switchboards, Motor Control Centers |
| Wire Gauge | 1/0 AWG - 500 kcmil (Cu/Al) |
| Max Wire | 500 kcmil |
| Min Wire | 1/0 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed Thermal, Adjustable Magnetic |
| Available Options | Shunt Trip, Auxiliary Switch, Undervoltage Release, Alarm Switch |
|---|---|
| Accessories | Load Side Lugs Included |
| Standards | UL 489, CSA C22.2 No. 5 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | Interchangeable Trip Unit, Trip-Free Mechanism, HACR Rated |
Product FAQs
5 answersWhich Siemens distribution panels and switchboards accept the KM3B300 breaker?
You can install this breaker in Siemens P4, P5, S4, and S5 panelboards. It is also compatible with SB1, SB2, and SB3 switchboards, as well as standard motor control centers.
What type of conductors can be used with the terminals on this breaker?
The factory lugs are rated for both copper and aluminum wire, accepting conductor sizes from 1/0 AWG up to 500 kcmil.
Does the KM3B300 offer adjustable trip settings?
Yes, while the thermal element for long-time overload protection is fixed, the magnetic trip element is adjustable to allow customization of the instantaneous short-circuit response.
What is the maximum fault current this breaker can safely interrupt?
The interrupting capacity depends on the system voltage. It is rated to safely clear faults up to 65kA at 240VAC, 50kA at 480VAC, and 22kA at 600VAC.
Is the KM3B300 part of a current or legacy Siemens product line?
This model is part of the legacy Siemens M Frames group, specifically the KM frame series.
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