Electrical Circuit Breakers – The Ultimate Guide to Brands and Compatibility

By James R. Leichter

The reason I wrote this article was because as I was updating our flat rate pricing system, I realized just how much the business of electrical circuit breakers has changed since I last updated that part of our inventory system. I decided to educate myself on the latest information and I decided to make an article out of it. I hope other people find it useful and maybe I’ll save them a little bit of trouble. I did use AI to help with fact checking. More importantly I used AI to serve as my editor – catching grammar, usage, and spelling errors. I make a lot of those kinds of errors.

Article Summary:

18 Minute Read Time

This guide provides a practical overview of residential circuit breakers, focusing on major brands, product lines, and compatibility concerns. It clarifies confusion around common breaker names such as Square D QO vs. Homeline, Eaton vs. Cutler-Hammer, and the use of tandem, twin, thin, and miniature breakers. Each brand’s residential offerings are listed, with insights into visual identification, typical usage, and interchangeability.

A detailed compatibility chart shows which breakers are approved or UL-classified for use in various electrical panels, with critical notes to help users avoid unsafe or non-compliant replacements. The guide emphasizes the importance of using manufacturer-approved breakers and understanding the difference between physical fit and true electrical compatibility.

It also explains the roles of modern breaker technologies, including AFCI, GFCI, dual-function, plug-on neutral, and thermal/hydraulic magnetic mechanisms. A glossary of key breaker terms is included, offering concise definitions for professionals and DIYers alike. There is an FAQ section.

The article further includes a section on discontinued or obsolete brands such as Zinsco, Federal Pacific, and ITE, warning against their continued use, and introduces Schneider Electric’s commercial PowerPact series for readers exploring higher-capacity solutions.

Written for homeowners, electricians, and HVAC technicians, this article aims to demystify circuit breakers and promote safer, more informed decisions when working with load centers and service panels.

Circuit Breaker Brands and Compatibility:

There are a lot of questions about brands and compatibility. Let’s try and clear some of them up.

Residential Breaker Brands (as of today):

1. Eaton®
2. Eaton Cutler-Hammer®
3. Siemens®
4. GE Q-Line®
5. Square D QO®
6. Square D Homeline®
7. Leviton®

Square D QO:

• Made for commercial use.
• They have trip indicators.
• In short, Square D compatible breakers are Siemens, Cutler Hammer, Eaton, GE Breaker, Murray, Westinghouse, and Home Fitline. Homeline and Square D QO breakers are explicitly NOT interchangeable.

Square D Homeline:

• Example Part Number: HOM120CP
• A product line by Square D, which is still in production.​
• The brand also makes a bolt-on kind called QOB. QOB breakers will work with panels meant for old style Square D breakers like NQ and NQOB.

Square D vs. Homeline:

• Both are made by Schneider Electric.
• QO (Qwik-Open) is the premium line, with a visual trip indicator and V-shaped metal bus, used in both residential and light commercial.
• Homeline is the economy residential line, no trip indicator, uses a flat aluminum bus.
• QO and Homeline are NOT interchangeable.

Eaton:

• Cutler-Hammer and the Eaton family of products are the same and compatible. Part numbers are the same.

Eaton vs. Cutler-Hammer:

• Eaton owns Cutler-Hammer, acquired in 1978. This brand’s products are still being manufactured.
• Residential breakers are often branded simply “Eaton”, especially the BR series (used in many home panels).
• Cutler-Hammer name is still used, mainly for legacy and commercial/industrial lines (e.g., CH series).

Key Visual Cues:

• BR breakers: Thinner, black, common in residential (home) panels.
• CH breakers: Tan or gray handles, premium line, usually commercial, more expensive, different bus stab design.

Breaker Types

Most manufacturers categorize their breakers by types. Not every manufacturer uses that term, but most have some type of type or category to distinguish the breaker’s purpose. Here’s an extended and organized list of circuit breaker types by manufacturer, with additional model lines and brief notes to help distinguish them.

Eaton / Cutler-Hammer Types

BR Series: Residential, plug-in type, commonly found in newer home panels. Thin profile.

CH Series: Premium residential and light commercial, bolt-on style. Known for tan handles.

CL Series: UL Classified breakers, designed to fit competitor panels (e.g., Square D, GE).

CHT Series: Tandem version of CH breakers for space-saving installs.

BQ / BAB Series: Commercial-grade, bolt-on style, used in panelboards and load centers.

GFCB / AFCI: Ground Fault and Arc Fault circuit interrupters for BR/CH series.

CAFCI / DF: Combination Arc Fault or Dual Function (AFCI + GFCI), available in BR and CH.

Siemens Types

QP Series: Most common plug-in residential breaker. Compatible with Siemens and Murray panels.

MP Series: Equivalent to QP; used interchangeably depending on panel labeling.

QT Series: Tandem breakers, fits two circuits in one slot (space-saving).

QAF / QPF Series: AFCI (QAF) and GFCI (QPF) breakers for residential panels.

QA/QJ Series: Commercial applications; QJ is bolt-on for higher amp loads.

HQP / HED / ED Series: Heavy-duty or commercial use (HED and ED are MCCBs).

Square D (by Schneider Electric) Types

QO Series: Premium residential/light commercial breakers with trip indicator and V-shaped bus.

QOB Series: Bolt-on version of QO for use in commercial panelboards (e.g., NQ, NQOB).

Homeline (HOM) Series: Budget residential line, plug-in style, not compatible with QO.

HOMT Series: Tandem Homeline breakers for adding circuits.

CAFI / DF Series: Arc Fault and Dual Function breakers for both QO and Homeline.

PowerPact Series: MCCBs for commercial/industrial applications (Q, H, J, L frames).

EHB / EDB / EGB / EJB Series: Industrial bolt-on types for panelboards and switchboards.

General Electric (GE) Types

THQL Series: Most common residential plug-in GE breaker.

THQP Series: Thin-style breakers. They allow more circuits in same space.

THQB / THHC / THLC: Bolt-on types for commercial panels.

GFEP / AFCI / Dual Function: Specialized breakers for AFCI/GFCI protection.

Spectra Series: Commercial/industrial MCCBs, often found in facility distribution panels.

Leviton Types

Smart GFCI / AFCI / Dual Function: Plug-on Neutral breakers with diagnostic LEDs.

LEV Series: Residential breaker line, part of Leviton’s whole load center system.

LEVQ Series: Qwik-Connect plug-in version with no pigtail needed.

Circuit Breaker Compatibility:

Ensuring the compatibility of circuit breakers with their respective panels is crucial for safety and compliance. Below is a general compatibility chart for common residential circuit breaker brands. Always consult the panel’s labeling and manufacturer documentation before making any replacements.​

Circuit Breaker Compatibility Chart:

Important Considerations:

• UL Classified Breakers: Some manufacturers produce breakers classified by Underwriters Laboratories (UL) for use in competitors’ panels. For instance, Eaton’s CL Series breakers are UL-classified for use in various panels, including certain Square D, Siemens, and GE models. Always refer to the breaker and panel documentation to confirm compatibility.
• Physical Fit vs. Electrical Compatibility: A breaker may physically fit into a panel but may not be electrically compatible or safe. Always ensure that any breaker used is both mechanically and electrically suitable for the panel.​
• Consult Manufacturer Documentation: Panel labels and manufacturer guidelines provide the most reliable information on compatible breakers. Deviating from these recommendations can lead to safety hazards and may violate electrical codes.​

⚠️ For a detailed and authoritative compatibility assessment, always refer to the panel’s labeling and consult with a licensed electrician.​

Discontinued or Obsolete Breaker Brands:

Federal Pacific: Known for the “Stab-Lok” line, Federal Pacific Electric’s circuit breakers were primarily manufactured between 1950 and 1980. Due to safety concerns and design flaws, these breakers are considered obsolete and are no longer in production. It’s recommended to replace these panels entirely with modern equipment from manufacturers like Eaton, GE, Siemens, or Square D. ​

ITE: Acquired by Siemens in the 1980s. Original ITE breakers are discontinued, but Siemens produces compatible replacements for many ITE models.​

Westinghouse: Acquired by Eaton Corporation in 1994. Many original Westinghouse circuit breakers, such as the EL300 series, have been discontinued and are considered obsolete. Eaton now produces compatible breakers that can serve as replacements. ​

Zinsco: Acquired by GTE-Sylvania in 1973, and the product line was later rebranded as Challenger. Due to design flaws leading to safety concerns, Zinsco panels and breakers are considered obsolete. Replacement with modern panels from manufacturers like Eaton, GE, Siemens, or Square D is recommended. ​

Breaker Part/Model Number Nomenclature

Circuit breaker manufacturers utilize specific part numbering conventions to convey essential information about their products, including series, amperage, poles, voltage rating, and special features. Understanding these conventions aids in selecting the appropriate breaker for a given application. It also helps you know what breaker you are looking at just by having the part number. The breaker description may not always tell you what you need to know, especially when looking at an inventory stocking list or flat-rate pricing book.

Example:

Series or type (e.g., BR, QO)
Amperage (e.g., 20, 30)
Number of poles (e.g., 1, 2)
Special features (e.g., GFCI, AFCI, DFC)

This is the part number for a type “QO”. 2-pole, 20-amp tandem (aka: twin) breaker: QO220220

✅ Understanding a little bit about breaker nomenclature helps me determine whether I have an adequate part description or possibly I have the wrong item number for a given item description. This helps me update our truck stocking lists and flat-rate pricing books.

Below is an overview of the part numbering schemes for Eaton (including Cutler-Hammer), Siemens, and Square D.​

Eaton / Cutler-Hammer

Prefixes:

• BR: Indicates the Type BR series, commonly used in residential applications.
• CH: Denotes the Type CH series, known for its tan handle and typically used in residential and light commercial settings.​

Suffixes and Infixes:

• Digits (e.g., 1520, 2020): Represent the amperage rating of the breaker. For instance:​
  • BR1520: A tandem breaker with one 15A and one 20A circuit.
  • CH260: A 60A, double-pole breaker.
• GF: Indicates a Ground Fault Circuit Interrupter (GFCI) breaker.​
  • CH230GF: A 30A, double-pole GFCI breaker.​
• AF: Signifies an Arc Fault Circuit Interrupter (AFCI) breaker.​
• DF: Stands for Dual Function, combining both GFCI and AFCI protections.​
  • BRAFGF120CS: A 20A, single-pole breaker with both AFCI and GFCI protections.

Siemens

Prefixes:

• Q: Denotes the Siemens Type Q series.​
  • QP: Standard plug-in breakers for residential use.​
  • QT: Tandem (twin) breakers, allowing two circuits in one space.​
  • QF: Ground Fault Circuit Interrupter breakers.​
  • QAF: Arc Fault Circuit Interrupter breakers.​

Numbering:

• Digits (e.g., 230, 250): Indicate the amperage rating and number of poles.​
  • Q230: A 30A, double-pole breaker.​
  • Q250: A 50A, double-pole breaker.

Square D

Prefixes:

• QO: Represents the QO® (Qwik-Open) series, known for its quick trip mechanism and visual trip indicator.​
• HOM: Indicates the Homeline® series, designed for residential applications.​

Suffixes and Infixes:

• Digits (e.g., 120, 230): Denote the amperage and number of poles.​
  • QO120: A 20A, single-pole breaker.​
  • HOM230: A 30A, double-pole breaker.​
• CP: Stands for Clamshell Packaging, indicating the type of packaging.​
  • HOM2100CP: A 100A, double-pole breaker in clamshell packaging. ​
• DFC: Denotes a Dual Function Circuit Breaker, providing both GFCI and AFCI protections.​
  • HOM115DFC: A 15A, single-pole dual function breaker. 

📌 Note: While these conventions are standard, it’s essential to consult the manufacturer’s documentation or a licensed electrician to ensure the correct breaker selection for specific applications. They may (and often do) change over time.

Breaker Item Description Advice

When creating inventory stocking lists or flat-rate pricing books, the item description is important. As an example, here is my recommendation for a Square D, model number QOB120VH breaker:

Breaker 1P 20A, Bolt-on 22KAIC QO Miniature, Square D, [QOB120VH]

📌 Note: The part number at the end is optional. Personally, I like to include it. If you include it, I recommend enclosing it in brackets. That makes it easier to find and remove that information, if needed.

Generic or Universal Part Numbers

Many contractors create a generic part number for their technicians. This works when you control what breakers they stock on their trucks and where the technician does not need to worry about detailed breaker specifications. A 2-pole 20-amp breaker might have the following part number: BKR220. You may use “BKR220E” for Eaton and “BKR220CH” for Cutler Hammer. A 1-pole, 15-amp, GFCI by Eaton might be “BKR115GFCIE”.

👉 There are a lot of “correct” ways to do this. No matter what you decide, just be consistent.

Circuit Breaker Terms:

10KAIC: Interrupt rating of 10,000 amps; the breaker can safely stop a short circuit of this magnitude.

22KA: Interrupt rating of 22,000 amps; higher fault current capacity than 10KAIC.

AFCI (Arc Fault Circuit Interrupter): Detects and trips on dangerous arcing faults to prevent electrical fires.

ARC/GFI / Dual Function ARC/GFI with Pigtail: Combines AFCI and GFCI protection in one breaker; pigtail wire connects to the panel’s neutral bar.

ARC-Fault: Protects against electrical arcing that can cause fires; required in many living areas.

Bolt-In Mount: Breaker is secured with a screw or bolt, providing a more secure connection, often in industrial panels.

Branch Circuit: Wiring and breakers that serve individual loads (e.g., outlets, lights) from the panel.

Breaker Handle Tie: A clip or bar that joins two single-pole breakers for use on a 240V circuit.

CCVH Tenant Breaker / Tenant Breaker: A breaker used in multi-tenant panels (like apartments); often controls power to one unit.

CTL (Circuit Total Limiting): Modern standard that limits the number of breakers based on panel design.

Double Pole (2P): Controls a 240V circuit using two hot wires; takes up two breaker slots.

GFCI (Ground Fault Circuit Interrupter): Trips when detecting leakage current to the ground, protecting people from shock.

GFI: Common shorthand for GFCI; same function.

Hydraulic Magnetic Branch: Uses magnetic and hydraulic mechanisms for precise tripping, unaffected by ambient temperature.

KA (Kilo Amps): Often used as a shorthand for KAIC. For example, 22KA typically means 22,000 amp interrupting capacity.

KAIC (Kilo Ampere Interrupting Capacity): The maximum short-circuit current a breaker can safely interrupt without damage. For example, 10KAIC means it can interrupt up to 10,000 amps.

Load Center: Another term for the electrical panel or breaker box in a residence.

Main Breaker: The master breaker that disconnects all power to the panel.

Magnetic Trip (Short Circuit): Instantaneous trip when current exceeds a threshold (typically 5–10× rated current), tripping in milliseconds.

Miniature: A small-sized breaker designed for residential or light commercial panels; fits standard slots.

Non-CTL (Non-Circuit Total Limiting): Breakers that bypass UL limits for the number of circuits in a panel, used only in certain cases like replacement.

Nomenclature: While not specific to only breakers, this term is often used when discussing part numbers. It is the correct term when referring to the rules or system used for naming or numbering parts, including circuit breakers. In this context, “breaker nomenclature” refers to the standardized format manufacturers use to create part numbers

Pigtail: A short white neutral wire attached to some breakers (usually GFCI/AFCI) that connects to the neutral bar.

Plug-On Neutral: Breaker connects directly to the panel’s neutral bar without a pigtail wire, simplifying install.

Single Pole (1P): Controls one circuit and connects to one hot wire; typically 120V.

Snap-In Mount: Another name for stab; breaker snaps into panel slots to connect.

Stab Mount: Breaker pushes into place and makes contact with bus bars via spring clips.

Standard Breaker: A single-pole or double-pole breaker that occupies one or two full panel slots, respectively.

Subpanel: A secondary panel fed from the main panel, often used for detached garages or additions.

Tandem: A breaker that fits two circuits into one standard breaker slot, using a shared mounting base.

Thermal Magnetic Branch: Uses heat and magnetic fields to detect overloads and short circuits; common in residential use.

Thermal Trip (Overload): Slower trip based on sustained overcurrent (e.g., 135–200% of rated load). Time can range from seconds to minutes.

Thin: Describes narrow breakers like tandems or miniatures; takes up less panel space.

Twin: Another name for a tandem breaker; allows two circuits in one slot.

UL Classified: Means the breaker is tested for use in another manufacturer’s panel; not original equipment but approved.

UL Listed: Indicates the breaker is certified by Underwriters Laboratories for safety and performance.

Frequently Asked Questions:

Question: Are there any specifications for how fast a breaker will trip?
Answer: Yes, breakers have trip curves or time-current characteristics that define how quickly they trip under different overload or fault conditions.

Types of Trip Curves (mainly in industrial/commercial use):

• Type B: Trips at 3–5× rated current (used for residential/light loads).
• Type C: Trips at 5–10× rated current (used for motor loads).
• Type D: Trips at 10–20× rated current (used for high inrush equipment).

💡 In residential use, exact timing isn’t always specified but follows UL standards (e.g., UL 489), ensuring consistent performance.

📌 Also see definitions for Thermal Trip (Overload) and Magnetic Trip (Short Circuit).

Question: Is Twin and Tandem the same?
Answer: Yes, typically interchangeable terms depending on manufacturer.

Question: Is Miniature and Thin the same?
Answer: Often used interchangeably, but “thin” refers more to form factor; “miniature” to type.

Question: Are GFI and GFCI the same thing?
Answer: Yes, GFI is an informal term for GFCI.

Question: Can I use any brand of breaker in my panel?
Answer:  No. Use only breakers listed on the panel label or UL-classified for that panel.

Question: What’s the difference between QO and Homeline?
Answer:  QO is Square D’s premium line with more features; Homeline is the budget line. They are not interchangeable.

Question: Can I replace a tandem breaker with two single breakers?
Answer:  Only if the panel has space and allows two breakers. Tandems are used to save space.

Question: What is a Plug-On Neutral panel?
Answer:  A panel that allows breakers to connect to the neutral bus without a pigtail, simplifying GFCI/AFCI installs.

Question: What causes a breaker to trip repeatedly?
Answer:  Possible causes include overload, short circuit, ground fault, or arc fault.

Question: Can I mix AFCI and GFCI protection?
Answer:  Yes. Use a dual-function breaker or combine AFCI breaker with a GFCI outlet when code allows.

Question: Are old panels compatible with modern breakers?
Answer:  Often not. Older panels may require obsolete or special-order breakers. Check with a licensed electrician.

Commercial Dedicated Breakers:

This article is mainly written for residential and cross residential/commercial breakers. These breakers are some of the more common for commercial use.

PowerPact® Family:
A family of molded case circuit breakers (MCCBs) by Schneider Electric, designed for commercial and industrial use. Offers a wide range of frame sizes, interrupt ratings, and advanced protection features.

PowerPact Q®
A specific model within the PowerPact family. The Q-frame breakers are 240V-rated, available up to 250A, and commonly used in light industrial and commercial panels. They offer thermal-magnetic or electronic trip units.

• Up to 250A, 240V
• Common in light commercial/industrial applications
• Thermal-magnetic and electronic options
• Compact footprint

PowerPact Q®

• Up to 250A, 480Y/277V
• Higher interrupting ratings than Q-frame
• For heavier-duty commercial loads
• Common upgrade from Q-frame for added protection

PowerPact J

• Up to 400A, 600Y/347V
• Ideal for mid-sized commercial/industrial panels
• Electronic trip options (LSI protection)
• Often used in distribution panels and motor control centers

PowerPact L

• Up to 600A, 600V
• Larger frame for industrial applications
• Advanced trip settings for selective coordination
• Supports communications and metering integration

Trademark and Copyright Acknowledgment:

All trademarks and copyrights are the property of their registered owners. Aptora® or the author makes no claims to these trademarks and copyrights. Aptora® is a registered trademark of Aptora Corporation.

About the Author
James R. Leichter has been called “the most trusted voice in the HVAC industry.” James is the founder and president of Aptora, makers of the HVAC industry’s top field service management software. He is a renowned HVAC business consultant, author, expert witness, master mechanic, and public speaker. James has built businesses from the ground up. His “been there and done that” experience means he can relate to anyone from technicians, administrators, to owners and executives. His highly motivational presentations provide practical insights that audiences can implement immediately.