Building Code Glossary
Panelboard: Building Code Definition
How the IRC 2009 define panelboard, 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
Panelboard is a defined term in the International Residential Code (IRC) 2009, in Electrical Definitions. The code's own words are: “A single panel or group of panel units designed for assembly in the form of a single panel, including buses and automatic overcurrent devices, and equipped with or without switches for the control of light, heat or power circuits, designed to be placed in a cabinet or cutout box placed in or against a wall …” 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 7 chapters of this corpus, most often in Branch Circuit and Feeder Requirements (IRC 2009), Swimming Pools (IRC 2009), General 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?
Panelboard — IRC 2009, Electrical Definitions:
A single panel or group of panel units designed for assembly in the form of a single panel, including buses and automatic overcurrent devices, and equipped with or without switches for the control of light, heat or power circuits, designed to be placed in a cabinet or cutout box placed in or against a wall, partition or other support and accessible only from the front.
What must be verified before using this guidance?
Panelboard is defined once in this corpus, in the Electrical Definitions chapter of the International Residential Code (IRC) 2009:
A single panel or group of panel units designed for assembly in the form of a single panel, including buses and automatic overcurrent devices, and equipped with or without switches for the control of light, heat or power circuits, designed to be placed in a cabinet or cutout box placed in or against a wall, partition or other support and accessible only from the front.
Where panelboard is used in the code
The term appears in 7 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.
| Chapter | Code | Mentions |
|---|---|---|
| Branch Circuit and Feeder Requirements | IRC 2009 | 15 |
| Swimming Pools | IRC 2009 | 15 |
| General Requirements | IRC 2009 | 11 |
| Power and Lighting Distribution | IRC 2009 | 10 |
| Building Services and Systems | IFC 2009 | 5 |
| Electrical Definitions | IRC 2009 | 1 |
| Services | IRC 2009 | 1 |
The term in use
How the code actually writes about panelboard, quoted from the 2009 text hosted here:
All conductors for multiwire branch circuits shall originate from the same panelboard or similar distribution equipment.
The junction box, transformer enclosure, or other enclosure in the supply circuit to a wet-niche or no-niche luminaire and the field-wiring chamber of a dry-niche luminaire shall be grounded to the equipment grounding terminal of the panelboard.
The space equal to the width and depth of the panelboard and extending from the floor to a height of 6 feet (1829 mm) above the panelboard, or to the structural ceiling, whichever is lower, shall be dedicated to the electrical installation.
The terms panelboard is built out of
The definition above leans on 5 other defined terms. Each carries its own code definition, and a local amendment to any of them changes what panelboard covers:
- Overcurrent — IRC 2009: Any current in excess of the rated current of equipment or the ampacity of a conductor.
- Accessible — IBC 2009: A site, building, facilityor portion thereof that complies with this chapter.
- Cutout Box — IRC 2009: An enclosure designed for surface mounting and having swinging doors or covers secured directly to and telescoping with the walls of the box proper (see "Cabinet").
- Automatic — IBC 2009: As applied to fire protection devices, a device or system providing an emergency function without the necessity for human intervention and activated as a result of a predetermined temperature rise, rate of temperature rise or combustion products.
- Control — IRC 2009: A manual or automatic device designed to regulate the gas, air, water or electrical supply to, or operation of, a mechanical system.
Panelboard: 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 | Branch Circuit and Feeder Requirements (IRC 2009) | |
| Re-check the requirement that uses it | Swimming Pools (IRC 2009) | |
| Re-check the requirement that uses it | General Requirements (IRC 2009) | |
| Re-check the requirement that uses it | Power and Lighting Distribution (IRC 2009) | |
| Confirm the dependent definition | Overcurrent | |
| Confirm the dependent definition | Accessible | |
| Confirm the dependent definition | Cutout Box | |
| 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
- Cutout Box: Building Code Definition
- Accessible: Building Code Definition
- Automatic: 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 panelboard?
The International Residential Code (IRC) 2009 defines it in Electrical Definitions as: “A single panel or group of panel units designed for assembly in the form of a single panel, including buses and automatic overcurrent devices, and equipped with or without switches for the control of light, heat or power circuits, designed to be placed in a cabinet or cutout box placed in or against a wall, partition or other support and accessible only from the front.” 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 panelboard?
In this corpus the term is used across 7 chapters, led by Branch Circuit and Feeder Requirements 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 a panelboard?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IRC 2009 states, in Electrical Definitions: “A single panel or group of panel units designed for assembly in the form of a single panel, including buses and automatic overcurrent devices, and equipped with or without switches for the control of light, heat or power circuits, designed to be placed in a cabinet or cutout box placed in or against a wall …” 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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