Siemens REF3B050 EF3B050 - 50A 3 Pole Molded Case Circuit Breaker
- 50A
- 3 Pole
- Bolt-On
Siemens
REF3B050
EF3B050 - 50A 3 Pole Molded Case Circuit Breaker
Brand
Siemens
SKU
REF3B050
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Siemens EF3B050 - 50A 3 Pole Molded Case Circuit Breaker
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Description
Designed for commercial power distribution, the Siemens REF3B050 is a 3-pole, 50A molded case circuit breaker rated for 600VAC and 250VDC systems. This bolt-on unit installs into compatible Siemens and I-T-E panelboards or switchboards. It serves as an exact replacement for the legacy ED63B050, ensuring seamless integration into existing E-Frame setups. Featuring fixed thermal magnetic trip units, it delivers reliable LI protection with a 14kAIC rating at 480VAC.Specifications
| Brand | Siemens |
|---|---|
| Part Number | REF3B050-R |
| Series | EF |
| Amperage | 50A |
| Poles | 3 |
| Mounting Style | Bolt-On |
| Voltage | 600VAC, 250VDC |
| Phase | 3 |
| AIC Rating | 18kA @ 240VAC, 14kA @ 480VAC, 14kA @ 600VAC, 10kA @ 250VDC |
| Terminal Type | Lugs |
|---|---|
| For Use With | Siemens / I-T-E Panelboards, Switchboards |
| Wire Gauge | 10-1/0 AWG (Cu/Al) |
| Max Wire | 1/0 AWG |
| Min Wire | 10 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, Undervoltage Release |
|---|---|
| Accessories | Lugs |
| Standards | NEMA AB-1, UL 489 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | Non-Interchangeable Trip |
Product FAQs
7 answersWhich enclosures are compatible with the EF3B050?
This breaker is designed exclusively for Siemens and legacy I-T-E panelboards and switchboards that accept E-frame molded case circuit breakers.
How is the EF3B050 installed in a panelboard?
This is a bolt-on molded case circuit breaker. It fastens directly to the bus bar in compatible Siemens and legacy I-T-E panelboards or switchboards, providing a secure connection for commercial and industrial applications.
What does the LI trip function mean on this breaker?
The LI designation indicates that the thermal-magnetic trip unit provides both Long-Time overload protection and Instantaneous short-circuit protection. Both the thermal and magnetic settings are fixed on this specific model.
Is the EF3B050 rated for use in DC circuits?
Yes, in addition to its AC voltage ratings up to 600V AC, this breaker is rated for 250V DC applications with a maximum interrupting capacity of 10kA.
What wire sizes are compatible with the EF3B050 terminals?
The included load side lugs accommodate 10 AWG to 1/0 AWG wire. Both copper and aluminum conductors are supported for installation.
Is the Siemens EF3B050 still manufactured?
No, the EF series is a legacy molded case circuit breaker family. While no longer in active production, it serves as a direct replacement for existing E-frame breakers in older Siemens and I-T-E enclosures.
Can I install this breaker in a GE or Square D panel?
No. To maintain safety standards and UL compliance, the EF3B050 must only be installed in Siemens or I-T-E panelboards and switchboards specifically designed to accept E-frame bolt-on breakers.
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