Building Code Glossary
Circuit Breaker: Building Code Definition
How the IRC 2009 define circuit breaker, where the wording differs, and which chapters depend on the term.
On this page
Last updated September 7, 2026 · Definitions quoted from the 2009 International Codes as transcribed in this site's building-codes collection, with the source chapter linked for each quotation. Usage counts are computed over the chapters hosted here, one copy per code. The [ICC code library](https://codes.iccsafe.org/codes) publishes the current model text and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) show which edition a jurisdiction has adopted; those sources control.
Direct answer
Circuit breaker is a defined term in the International Residential Code (IRC) 2009, in Electrical Definitions. The code's own words are: “A device designed to open and close a circuit by nonautomatic means and to open the circuit automatically on a predetermined overcurrent without damage to itself when properly applied within its rating.” No other I-Code in this corpus defines it, so the IRC 2009 definition is the one to work from. The term is used in 8 chapters of this corpus, most often in Services (IRC 2009), Devices and Luminaires (IRC 2009), Branch Circuit and Feeder Requirements (IRC 2009). These pages transcribe the 2009 model text; verify the definition against the edition and amendments your authority having jurisdiction has adopted.
Content and cited inputs reviewed by Scott Barrington, Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.
What does this term mean?
Circuit Breaker — IRC 2009, Electrical Definitions:
A device designed to open and close a circuit by nonautomatic means and to open the circuit automatically on a predetermined overcurrent without damage to itself when properly applied within its rating.
What must be verified before using this guidance?
Circuit Breaker is defined once in this corpus, in the Electrical Definitions chapter of the International Residential Code (IRC) 2009:
A device designed to open and close a circuit by nonautomatic means and to open the circuit automatically on a predetermined overcurrent without damage to itself when properly applied within its rating.
Where circuit breaker is used in the code
The term appears in 8 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.
| Chapter | Code | Mentions |
|---|---|---|
| Services | IRC 2009 | 11 |
| Devices and Luminaires | IRC 2009 | 10 |
| Branch Circuit and Feeder Requirements | IRC 2009 | 6 |
| Electrical Definitions | IRC 2009 | 3 |
| Commercial Energy Efficiency | IECC 2009 | 1 |
| Welding and Other Hot Work | IFC 2009 | 1 |
| Appliance Installation | IRC 2009 | 1 |
| Power and Lighting Distribution | IRC 2009 | 1 |
The term in use
How the code actually writes about circuit breaker, quoted from the 2009 text hosted here:
Overcurrent devices shall not be connected in series with a grounded service conductor except where a circuit breaker is used that simultaneously opens all conductors of the circuit.
Where single-throw switches or circuit breaker handles are operated vertically rather than rotationally or horizontally, the up position of the handle shall be the ON position.
A switch or circuit breaker shall be provided so that fixed electric welders and control equipment can be disconnected from the supply circuit.
The terms circuit breaker is built out of
The definition above leans on 2 other defined terms. Each carries its own code definition, and a local amendment to any of them changes what circuit breaker covers:
- Overcurrent — IRC 2009: Any current in excess of the rated current of equipment or the ampacity of a conductor.
- Device — IRC 2009: Aunit of an electrical system that carries or controls electrical energy as it principal function.
Circuit Breaker: what to open, and in what order
Every row is a document this term depends on. The ICC code library and the ICC adoption maps cover the middle rows.
| Check | Where | Confirmed |
|---|---|---|
| Read the definition in the adopted IRC | Electrical Definitions | |
| Re-check the requirement that uses it | Services (IRC 2009) | |
| Re-check the requirement that uses it | Devices and Luminaires (IRC 2009) | |
| Re-check the requirement that uses it | Branch Circuit and Feeder Requirements (IRC 2009) | |
| Re-check the requirement that uses it | Electrical Definitions (IRC 2009) | |
| Confirm the dependent definition | Overcurrent | |
| Confirm the dependent definition | Device | |
| Local amendment to any of the above | Jurisdiction's amendment list |
A research aid, not a code determination. The authority having jurisdiction decides which edition and which amendments apply.
Where can you explore related guidance?
- Explore all glossary guidance
- Overcurrent: Building Code Definition
- Device: Building Code Definition
Sources and method
Definitions quoted from the 2009 International Codes as transcribed in this site's building-codes collection, with the source chapter linked for each quotation. Usage counts are computed over the chapters hosted here, one copy per code. The ICC code library publishes the current model text and the ICC adoption maps show which edition a jurisdiction has adopted; those sources control.
Source links
Frequently asked questions
What is the code definition of circuit breaker?
The International Residential Code (IRC) 2009 defines it in Electrical Definitions as: “A device designed to open and close a circuit by nonautomatic means and to open the circuit automatically on a predetermined overcurrent without damage to itself when properly applied within its rating.” The 2009 model text is reproduced here; the definition that binds your project is the one in the edition your jurisdiction has adopted, as amended locally.
Which parts of the code depend on circuit breaker?
In this corpus the term is used across 8 chapters, led by Services in the IRC 2009. Those are the sections whose scope moves if the definition is amended locally, so read them together with Chapter 2 rather than on their own.
What is the definition of circuit breaker?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IRC 2009 states, in Electrical Definitions: “A device designed to open and close a circuit by nonautomatic means and to open the circuit automatically on a predetermined overcurrent without damage to itself when properly applied within its rating.” It is defined in IRC 2009. Because it is a defined term, whatever the adopted edition says it means is what every section using it means — so check Chapter 2 of that edition and any local amendment before relying on this wording.
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