Siemens KM3B800 Molded Case Circuit Breaker
- 800A
- 3 Pole
- Bolt-On
Quantity
Siemens KM3B800 - 800A 3 Pole Molded Case Circuit Breaker
Re-Certified
Quantity
Description
Engineered for industrial applications, the Siemens KM3B800 is a 3-pole, 800A molded case circuit breaker featuring an interchangeable thermal-magnetic trip unit. This bolt-on MCCB mounts into Siemens P4 and P5 panelboards, SB switchboards, and MCCs. It serves as a legacy solution, replaced by the HMD63B800 (adapter kit required). Rated for 600VAC, it delivers a 50kAIC interrupt capacity at 480V. Load side lugs are included for standard commercial installations.Specifications
| Brand | Siemens |
|---|---|
| Part Number | KM3B800-R |
| Series | KM |
| Amperage | 800A |
| 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 | 3 Cables: 250-500 kcmil (Cu/Al) OR 2 Cables: 500-750 kcmil (Cu/Al) |
| Max Wire | 750 kcmil |
| Min Wire | 250 kcmil |
| 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
6 answersWhat equipment is compatible with the KM3B800 circuit breaker?
This bolt-on MCCB mounts directly to the bus in Siemens P4, P5, S4, and S5 panelboards, as well as SB1, SB2, and SB3 switchboards and motor control centers.
What wire sizes are accepted by the lugs on this breaker?
The standard lugs accept either three cables ranging from 250 to 500 kcmil or two cables ranging from 500 to 750 kcmil per phase. Both copper and aluminum conductors are supported.
How does the trip unit operate on this breaker?
It features a thermal magnetic trip unit with Long-Time and Instantaneous (LI) functions. The thermal element is fixed, while the magnetic instantaneous trip is adjustable to coordinate with your specific system requirements.
Is the KM3B800 still in active production?
The KM frame is a legacy Siemens product. When sourcing a direct modern replacement, the HMD63B800 is often used, though it requires a specific adapter kit to fit into the existing panelboard or switchboard space.
Can the trip unit be swapped or replaced in the field?
Yes, the KM3B800 features an interchangeable trip unit design. This allows the trip unit to be removed and replaced without having to unbolt the entire breaker frame from the panelboard.
Can this breaker be used in direct current (DC) applications?
No, the KM3B800 is specifically rated for alternating current (AC) systems up to 600VAC. It is not listed for use in DC applications.
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