Siemens / ITE JK3B125 Molded Case Circuit Breaker
- 125A
- 3 Pole
- Bolt-On
Quantity
Siemens / ITE JK3B125 - 125A 3 Pole Molded Case Circuit Breaker
Re-Certified
Quantity
Description
Providing robust overcurrent protection, the Siemens JK3B125 is a 3-pole, 125A molded case circuit breaker. It is designed for commercial power distribution systems. This bolt-on breaker installs into Siemens P4 and P5 panelboards, as well as legacy ITE CDP enclosures. It is an exact fit for older installations, while the JXD63B125 serves as the modern replacement. Featuring an interchangeable trip unit, it delivers 22 kAIC at 480VAC and includes adjustable magnetic settings.Specifications
| Brand | Siemens / ITE |
|---|---|
| Part Number | JK3B125-R |
| Series | JK |
| Amperage | 125A |
| Poles | 3 |
| Mounting Style | Bolt-On |
| Voltage | 240VAC, 480VAC, 600VAC, 250VDC |
| Phase | 3 |
| AIC Rating | 25kA @ 240VAC, 22kA @ 480VAC, 18kA @ 600VAC, 10kA @ 250VDC |
| Frame Type | JK |
|---|---|
| Terminal Type | Lugs |
| For Use With | Siemens P4 Panelboards, Siemens P5 Panelboards, ITE CDP Panelboards, Switchboards |
| Wire Gauge | 4 AWG - 300 kcmil (Cu/Al) |
| Max Wire | 300 kcmil |
| Min Wire | 4 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, Alarm Switch, Undervoltage Release, Lug Kits, Padlock Attachment |
|---|---|
| Accessories | Lugs |
| Standards | UL 489, NEMA AB-1, CSA C22.2 No. 5 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | Interchangeable Trip Unit, HACR Rated |
Product FAQs
6 answersWhich panelboards are compatible with the JK3B125 circuit breaker?
This bolt-on breaker is designed to mount directly into Siemens P4 and P5 panelboards, legacy ITE CDP panelboards, and compatible commercial switchboards.
What type of conductors can be terminated on the JK3B125?
The included factory lugs are dual-rated for both copper and aluminum conductors, accepting wire sizes from 4 AWG up to 300 kcmil. Ensure proper torque specifications are followed during installation to maintain a secure connection.
How does the trip unit on the JK3B125 operate?
It utilizes a thermal magnetic trip unit with a fixed thermal element for standard overload protection and an adjustable magnetic element. The adjustable magnetic setting allows electricians to fine-tune the instantaneous short-circuit response to coordinate with downstream devices.
What is the modern replacement for the legacy JK3B125?
The Siemens JXD63B125 serves as the direct modern cross-reference and exact fit replacement for older installations requiring a 125A, 3-pole J-frame breaker.
Is the JK3B125 suitable for direct current systems?
Yes, in addition to standard AC systems, this thermal magnetic breaker is rated for use in DC applications up to 250VDC, where it provides an interrupting capacity of 10kA.
What safety precautions are required when installing this bolt-on breaker?
Always de-energize the panelboard or switchboard before installation. Verify that power is completely disconnected using a properly rated voltage tester to prevent arc flash and electrical shock hazards during the bolt-on process.
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