Free Shipping Over $99
Siemens EF3B125 Molded Case Circuit Breaker
- 125A
- 3 Pole
- Bolt-On
Siemens
EF3B125
Molded Case Circuit Breaker
Brand
Siemens
SKU
EF3B125
Quantity
Shop with Confidence
Add an extra year of protection in your cart.
Siemens EF3B125 - 125A 3 Pole Molded Case Circuit Breaker
Re-Certified
Quantity
Similar Items
30A 3 Pole Molded Case Circuit Breaker
20A 3 Pole Molded Case Circuit Breaker
20A 3 Pole Molded Case Circuit Breaker
Description
Serving as a robust protection solution, the Siemens EF3B125 is a 125A, 3-pole molded case circuit breaker. It utilizes fixed thermal and magnetic trip elements to safeguard commercial circuits up to 600VAC. Designed for bolt-on installation, it fits into Siemens P1, P2, and P3 panelboards as well as older I-T-E systems. While this legacy EF-frame model is highly sought after, it is replaced by the ED63B125. The breaker provides a 14kAIC rating at 480VAC and accommodates 4-3/0 AWG wire.Specifications
| Brand | Siemens |
|---|---|
| Part Number | EF3B125-R |
| Series | EF |
| Amperage | 125A |
| 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 P1, P2, P3 Panelboards, Legacy I-T-E Panelboards |
| Wire Gauge | 4-3/0 AWG (Cu/Al) |
| Max Wire | 3/0 AWG |
| Min Wire | 4 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 | Load Side Lugs Included |
| Standards | NEMA AB-1, UL 489 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, Non-Interchangeable Trip |
Product FAQs
5 answersWhich panelboards are compatible with the EF3B125 circuit breaker?
This bolt-on breaker is designed to fit modern Siemens P1, P2, and P3 panelboards. It is also fully backwards compatible with legacy I-T-E panelboards that accept E frame breakers.
What is the current replacement for the legacy EF3B125?
The EF3B125 is part of the legacy EF frame series. For new installations or direct replacements, Siemens now offers the Sentron ED frame equivalent under catalog number ED63B125.
Are the thermal and magnetic trip elements adjustable on this model?
No, this breaker utilizes a fixed thermal and fixed magnetic trip unit. It provides standard long time and instantaneous (LI) protection but cannot be adjusted in the field.
Can this breaker be used in direct current (DC) applications?
Yes, while primarily used in AC systems up to 600VAC, the EF3B125 is also rated for 250VDC systems with a 10kA interrupting capacity.
Does the EF3B125 include both line and load side lugs?
No, as a panelboard-mounted bolt-on breaker, the line side connects directly to the panel bus. It comes complete with load side lug terminals that accept 4 AWG to 3/0 AWG copper or aluminum wire.
SuperClub
Join free. Get 500 SuperPoints.
Earn points on eligible purchases and redeem them at checkout.
100 SuperPoints = $1 off.
Warranties
Add an extra year of protection
60-Day Warranty
Your purchase includes 60 days of SuperBreakers warranty coverage.
Add a 1-year warranty extension in your cart.
Get a Quote
Don’t see what you’re looking for?
We source obsolete and hard-to-find parts every day.
Shipping
Free Shipping Policy
Parcel shipments with item value over $99 qualify for free economy shipping within the continental US. Please call to confirm special handling instructions. We do not charge a handling fee or require a minimum amount on any order. SuperBreakers does not ship on customer accounts.
Same Day Shipping
We strive to ship out your items the same day the order is placed. In rare circumstances SuperBreakers may reserve up to 5 business days to consolidate orders for complete shipment.
Expedited Shipments
Orders being shipped via Next Day Air, 2 Day Shipping or 3 Day Shipping must be received by 3 PM EST to guarantee same-day shipments. Expedited orders only ship on normal business days. Shipments will NOT be sent out on Saturdays and Sundays.
International Shipping
All International orders require a $1,000 minimum order threshold. Due to the special nature of these shipments, we require that these be placed with a SuperBreakers representative. Additional shipping and instructions will apply. All International Orders are Non-Cancel and Non-Refundable.
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
Search
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.