# Fitting: Building Code Definition

> How the IRC 2009 define fitting, where the wording differs, and which chapters depend on the term.

- Canonical: https://harth.build/resources/glossary/fitting/
- Last updated: 2026-09-07
- Data source: 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.

## Key facts

| Fact | Value |
| --- | --- |
| Defined in | IRC 2009 (2009 editions transcribed in this corpus) |
| Primary source | IRC 2009 Electrical Definitions (model text, not a jurisdiction's adopted text) |
| Chapters using the term | 76 (counted across the codes hosted here) |
| Wording identical across codes | Single code (compare before citing one code's wording under another) |

## Direct answer

Fitting is a defined term in the International Residential Code (IRC) 2009, in Electrical Definitions. The code's own words are: “An accessory such as a locknut, bushing or other part of a wiring system that is intended primarily to perform a mechanical rather than an electrical function.” 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 76 chapters of this corpus, most often in Fuel Gas (IRC 2009), Water Supply and Distribution (IPC 2009), Sanitary Drainage (IRC 2009). These pages transcribe the 2009 model text; verify the definition against the edition and amendments your authority having jurisdiction has adopted. Record the jurisdiction, the adopted edition, the application date and any local amendment that rewrites the definition before you use it on a live project, because a term redefined by amendment changes every requirement that depends on it.

*Content and cited inputs reviewed by [Scott Barrington](https://nz.linkedin.com/in/barrington), Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.*

## What does this term mean?

**Fitting** — IRC 2009, Electrical Definitions:

> An accessory such as a locknut, bushing or other part of a wiring system that is intended primarily to perform a mechanical rather than an electrical function.

![Labeled code-term definition diagram: Fitting: Building Code Definition](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/glossary/fitting/diagram-1344.webp)

*How the IRC 2009 define fitting, where the wording differs, and which chapters depend on the term.*

## What must be verified before using this guidance?

**Fitting** is defined once in this corpus, in the [Electrical Definitions](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/electrical-definitions.md) chapter of the International Residential Code (IRC) 2009:

> An accessory such as a locknut, bushing or other part of a wiring system that is intended primarily to perform a mechanical rather than an electrical function.

## Where fitting is used in the code

The term appears in 76 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.

| Chapter | Code | Mentions |
| --- | --- | --- |
| [Fuel Gas](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/fuel-gas.md) | IRC 2009 | 118 |
| [Water Supply and Distribution](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/water-supply-and-distribution.md) | IPC 2009 | 83 |
| [Sanitary Drainage](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/sanitary-drainage.md) | IRC 2009 | 82 |
| [Water Supply and Distribution](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/water-supply-and-distribution.md) | IRC 2009 | 76 |
| [Sanitary Drainage](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/sanitary-drainage.md) | IPC 2009 | 72 |
| [Hydronic Piping](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/hydronic-piping.md) | IMC 2009 | 70 |
| [Power and Lighting Distribution](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/power-and-lighting-distribution.md) | IRC 2009 | 62 |
| [Hvdronic Piping](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/hvdronic-piping.md) | IRC 2009 | 39 |
| [Flammable and Combustible Liquids](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/flammable-and-combustible-liquids.md) | IFC 2009 | 38 |
| [Definitions](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/definitions.md) | IPC 2009 | 32 |
| [Definitions](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/definitions.md) | IRC 2009 | 31 |
| [Fixtures, Faucets and Fixture Fittings](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/fixtures-faucets-and-fixture-fittings.md) | IPC 2009 | 30 |

_64 further chapters mention the term._

### The term in use

How the code actually writes about fitting, quoted from the 2009 text hosted here:

> Metallic pipe and fitting threads shall be taper pipe threads and shall comply with ASME B1.20.1.

— [IRC 2009 §G2414.9](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/fuel-gas.md)

> Hot water and cold water manifolds installed with gridded or parallel connected individual distribution lines to each fixture or fixture fitting shall be designed in accordance with Sections 604.10.1 through 604.10.3.

— [IPC 2009 §604.10](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/water-supply-and-distribution.md)

> Joints between copper or copper-alloy tubing and galvanized steel pipe shall be made with a brass converter fitting or dielectric fitting.

— [IRC 2009 §P3003.18.2](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/sanitary-drainage.md)


## The terms fitting is built out of

The definition above leans on 1 other defined term. Each carries its own code definition, and a local amendment to any of them changes what fitting covers:

- **[System](https://harth.build/resources/glossary/system.md)** — IFC 2009: An assembly of equipment consisting of a tank, container or containers, appurtenances, pumps, compressors and connecting piping.

## Fitting: what to open, and in what order

Every row is a document this term depends on. The [ICC code library](https://codes.iccsafe.org/codes) and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-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 | Fuel Gas (IRC 2009) | |
| Re-check the requirement that uses it | Water Supply and Distribution (IPC 2009) | |
| Re-check the requirement that uses it | Sanitary Drainage (IRC 2009) | |
| Re-check the requirement that uses it | Water Supply and Distribution (IRC 2009) | |
| Confirm the dependent definition | System | |
| 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](https://harth.build/resources/glossary.md)
- [System: Building Code Definition](https://harth.build/resources/glossary/system.md)
- [Appliance: Building Code Definition](https://harth.build/resources/glossary/appliance.md)
- [Plenum: Building Code Definition](https://harth.build/resources/glossary/plenum.md)
- [Outlet: Building Code Definition](https://harth.build/resources/glossary/outlet.md)

## 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](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.

### Source links

- [codes.iccsafe.org](https://codes.iccsafe.org/codes)

- [iccsafe.org](https://www.iccsafe.org/advocacy/code-adoption-maps/)

## Frequently asked questions

### What is the code definition of fitting?

The International Residential Code (IRC) 2009 defines it in Electrical Definitions as: “An accessory such as a locknut, bushing or other part of a wiring system that is intended primarily to perform a mechanical rather than an electrical function.” 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 fitting?

In this corpus the term is used across 76 chapters, led by Fuel Gas 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 "fitting" in construction?

In the 2009 I-Codes hosted here it is a defined term rather than a description. The IRC 2009 states, in Electrical Definitions: “An accessory such as a locknut, bushing or other part of a wiring system that is intended primarily to perform a mechanical rather than an electrical function.” 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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