Circuit Breaker Identification Guide
Proper circuit breaker identification is essential when replacing a faulty breaker, upgrading an electrical panel, or locating a hard-to-find replacement. Many circuit breakers look similar, but differences in manufacturer, amperage, voltage rating, and panel compatibility can make selecting the correct replacement challenging.
This Circuit Breaker Identification Guide will help homeowners, electricians, contractors, and facility managers identify circuit breakers and locate compatible replacement breakers for residential, commercial, and industrial electrical systems.
Why Circuit Breaker Identification Matters
Installing the wrong breaker can create safety hazards, cause nuisance tripping, or damage electrical equipment. Before replacing a breaker, it is important to identify:
- Manufacturer and brand
- Breaker model number
- Amperage rating
- Voltage rating
- Breaker type
- Panel compatibility
Correct identification helps ensure safe operation and compliance with electrical codes.
Step 1: Identify the Breaker Manufacturer
The first step is determining who manufactured the breaker. Most breakers have the manufacturer's name printed on the handle, side label, or front face.
Common circuit breaker manufacturers include:
- Square D
- Siemens
- Cutler Hammer / Eaton
- General Electric (GE)
- Federal Pacific (FPE)
- Zinsco
- Challenger
- Bryant
- Pushmatic
- Westinghouse
If the label is damaged or missing, a qualified electrical supplier may still be able to identify the breaker based on its physical design.
Step 2: Locate the Amperage Rating
The breaker amperage is usually displayed prominently on the breaker handle.
Common breaker sizes include:
- 15 Amp
- 20 Amp
- 30 Amp
- 40 Amp
- 50 Amp
- 60 Amp
- 100 Amp
- 200 Amp
Learn more in our Circuit Breaker Amperage Guide.
Step 3: Determine the Breaker Type
Several breaker styles are commonly used in residential and commercial electrical systems.
- Single-Pole Breakers
- Double-Pole Breakers
- Tandem Circuit Breakers
- GFCI Circuit Breakers
- AFCI Circuit Breakers
- Bolt-On Circuit Breakers
- Molded Case Circuit Breakers
Identifying the breaker type is often necessary before purchasing a replacement.
Learn more about Tandem Circuit Breakers and GFCI Circuit Breakers.
Step 4: Check the Model Number
Most breakers include a manufacturer part number or catalog number printed on the side or rear label. This number is often the easiest way to locate an exact replacement breaker.
Examples may include:
- QO120
- QO220
- QP120
- BR120
- THQL1120
Having the model number available can greatly speed up the identification process.
Identifying Obsolete Circuit Breakers
Many older electrical systems still contain obsolete breakers that are no longer manufactured. These breakers often require specialized sourcing through surplus and obsolete electrical suppliers.
Some of the most commonly requested obsolete breakers include:
- Federal Pacific (FPE)
- Zinsco
- Challenger
- Pushmatic
- Bryant
- Bulldog
Learn more on our Obsolete Circuit Breakers page.
How to Identify a Replacement Circuit Breaker
When searching for a replacement breaker, compare the following:
- Manufacturer
- Model number
- Amperage rating
- Voltage rating
- Physical dimensions
- Panel compatibility
Many breakers may appear similar but are not approved for use in the same electrical panel.
Visit our Circuit Breaker Compatibility Guide for more information.
Hard-to-Find Circuit Breakers in San Diego
Electrical Supplies Unlimited specializes in identifying and sourcing hard-to-find circuit breakers in San Diego. Our inventory includes new, used, surplus, and obsolete breakers from many leading manufacturers.
Whether you're looking for a discontinued breaker, replacement panel component, or obsolete electrical equipment, our experienced staff can often help locate the correct part.
Visit our Hard to Find Circuit Breakers San Diego page to learn more.
Need Help Identifying a Circuit Breaker?
If you're unsure which breaker you have, bring your breaker into Electrical Supplies Unlimited or contact our team. We can often identify difficult-to-read model numbers, obsolete breakers, and compatible replacement options.
With over 40 years of experience, ESU is one of San Diego's trusted sources for circuit breakers, transformers, electrical panels, and hard-to-find electrical equipment.