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Siemens EF3B050 Molded Case Circuit Breaker
- 50A
- 3 Pole
- Bolt-On
Siemens
EF3B050
Molded Case Circuit Breaker
Brand
Siemens
SKU
EF3B050
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Siemens EF3B050 - 50A 3 Pole Molded Case Circuit Breaker
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Description
Operating as a crucial safety device for commercial facilities, this 50A molded case circuit breaker features fixed thermal and magnetic trip elements. Installation is straightforward as it bolts into older FC-1 panelboards and FC-20 switchboards from Siemens or I-T-E. When a modern equivalent is required, the ED63B050 serves as the official factory replacement. With an 18kAIC rating at 240VAC, it provides substantial short-circuit protection for aging electrical infrastructure.Specifications
| Brand | Siemens |
|---|---|
| Part Number | EF3B050-R |
| Series | EF |
| Amperage | 50A |
| Poles | 3 |
| Mounting Style | Bolt-On |
| Voltage | 240VAC, 480VAC, 600VAC, 250VDC |
| Phase | 3 |
| AIC Rating | 18kA @ 240VAC, 14kA @ 480VAC, 14kA @ 600VAC, 10kA @ 250VDC |
| Frame Type | EF |
|---|---|
| Terminal Type | Lugs |
| For Use With | Siemens / I-T-E Panelboards, FC-1 Panelboards, FC-20 Switchboards |
| Wire Gauge | 14-1/0 AWG (Cu), 12-1/0 AWG (Al) |
| Max Wire | 1/0 AWG |
| Min Wire | 14 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, Undervoltage Release, Alarm Switch |
|---|---|
| Accessories | Load Side Lugs (LN1-E100) |
| Standards | UL 489, NEMA AB-1 |
| Approval | UL, CSA |
| Temp Rating | 40C |
| Construction Features | Non-Interchangeable Trip |
Product FAQs
6 answersWhich panelboards and switchboards are compatible with the EF3B050 circuit breaker?
The EF3B050 is designed for use in legacy Siemens and I-T-E distribution equipment, specifically FC-1 panelboards and FC-20 switchboards. It requires a bolt-on connection.
What wire sizes are accepted by the lugs on the EF3B050?
The standard lugs on this breaker accept 14 to 1/0 AWG copper (Cu) wire, or 12 to 1/0 AWG aluminum (Al) wire.
Can the Siemens EF3B050 be used in DC applications?
Yes, this thermal magnetic breaker is rated for up to 250VDC with a maximum interrupting capacity of 10kAIC.
Why is the EF3B050 sometimes labeled as I-T-E instead of Siemens?
Siemens acquired I-T-E and continued manufacturing their breaker lines. The EF3B050 is a legacy E-Frame breaker that may carry either the I-T-E or Siemens brand name depending on its production date, but both versions are the exact same physical and electrical component.
Are the trip settings on the EF3B050 adjustable?
No, the EF3B050 features a fixed thermal and fixed magnetic trip unit. It provides standard Long-Time and Instantaneous protection functions that cannot be adjusted in the field.
Is the Siemens EF3B050 circuit breaker still actively manufactured?
No, the EF3B050 is a legacy E-Frame breaker that has been discontinued by the manufacturer. It is currently sourced to maintain and service existing Siemens and I-T-E panels rather than for new installations.
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Reviews
Review summary
Customers rate this product 5.0 out of 5 based on 2 reviews.
Total 5 star reviews: 2 Total 4 star reviews: 0 Total 3 star reviews: 0 Total 2 star reviews: 0 Total 1 star reviews: 0
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Rating
2 reviews
- VGVictor G.Verified BuyerRated 5 out of 5 stars11/6/25Breakers fit my needs
I wish I would of shopped this I found exact breaker for 400.00 cheaper
- RFRobert F.ReviewingSiemens EF3A100 - 100A 3 Pole Motor Circuit ProtectorI recommend this productRated 5 out of 5 stars7/25/22Fast order and service for a part in good condition
Fast order and service for a part in good condition.