# Nameplate Horsepower: Building Code Definition > How the IECC 2009 define nameplate horsepower, where the wording differs, and which chapters depend on the term. - Canonical: https://harth.build/resources/glossary/nameplate-horsepower/ - 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 | IECC 2009 (2009 editions transcribed in this corpus) | | Primary source | IECC 2009 Definitions (model text, not a jurisdiction's adopted text) | | Chapters using the term | 5 (counted across the codes hosted here) | | Wording identical across codes | Single code (compare before citing one code's wording under another) | ## Direct answer Nameplate horsepower is a defined term in the International Energy Conservation Code (IECC) 2009, in Definitions. The code's own words are: “The nominal motor horse-power rating stamped on the motor nameplate.” No other I-Code in this corpus defines it, so the IECC 2009 definition is the one to work from. The term is used in 5 chapters of this corpus, most often in Commercial Energy Efficiency (IECC 2009), Fire Protection Systems (IBC 2009), Definitions (IECC 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? **Nameplate Horsepower** — IECC 2009, Definitions: > The nominal motor horse-power rating stamped on the motor nameplate. ![Labeled code-term definition diagram: Nameplate Horsepower: Building Code Definition](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/glossary/nameplate-horsepower/diagram-1344.webp) *How the IECC 2009 define nameplate horsepower, where the wording differs, and which chapters depend on the term.* ## What must be verified before using this guidance? **Nameplate Horsepower** is defined once in this corpus, in the [Definitions](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/definitions.md) chapter of the International Energy Conservation Code (IECC) 2009: > The nominal motor horse-power rating stamped on the motor nameplate. ## Where nameplate horsepower is used in the code The term appears in 5 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next. | Chapter | Code | Mentions | | --- | --- | --- | | [Commercial Energy Efficiency](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/commercial-energy-efficiency.md) | IECC 2009 | 9 | | [Fire Protection Systems](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-protection-systems.md) | IBC 2009 | 2 | | [Definitions](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/definitions.md) | IECC 2009 | 2 | | [Fire Protection Systems](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/fire-protection-systems.md) | IFC 2009 | 2 | | [Exhaust Systems](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/exhaust-systems.md) | IMC 2009 | 2 | ### The term in use How the code actually writes about nameplate horsepower, quoted from the 2009 text hosted here: > Each HVAC system having a total fan system motor nameplate horsepower (hp) exceeding 5 horsepower (hp) shall meet the provisions of Sections 503.2.10.1 through 503.2.10.2. — [IECC 2009 §503.2.10](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/commercial-energy-efficiency.md) > Motors driving fans shall not be operated beyond their nameplate horsepower (kilowatts), as determined from measurement of actual current draw, and shall have a minimum service factor of 1.15. — [IBC 2009, Fire Protection Systems](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-protection-systems.md) > Motors driving fans shall not be operating beyond their nameplate horsepower (kilowatts) as determined from measurement of actual current draw. — [IMC 2009, Exhaust Systems](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/exhaust-systems.md) ## Nameplate Horsepower: 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 IECC | Definitions | | | Re-check the requirement that uses it | Commercial Energy Efficiency (IECC 2009) | | | Re-check the requirement that uses it | Fire Protection Systems (IBC 2009) | | | Re-check the requirement that uses it | Definitions (IECC 2009) | | | Re-check the requirement that uses it | Fire Protection Systems (IFC 2009) | | | 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) - [Building: Building Code Definition](https://harth.build/resources/glossary/building.md) - [Construction Documents: Building Code Definition](https://harth.build/resources/glossary/construction-documents.md) - [Registered Design Professional: Building Code Definition](https://harth.build/resources/glossary/registered-design-professional.md) - [Dwelling Unit: Building Code Definition](https://harth.build/resources/glossary/dwelling-unit.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 nameplate horsepower? The International Energy Conservation Code (IECC) 2009 defines it in Definitions as: “The nominal motor horse-power rating stamped on the motor nameplate.” 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 nameplate horsepower? In this corpus the term is used across 5 chapters, led by Commercial Energy Efficiency in the IECC 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 nameplate horsepower? In the 2009 I-Codes hosted here it is a defined term rather than a description. The IECC 2009 states, in Definitions: “The nominal motor horse-power rating stamped on the motor nameplate.” It is defined in IECC 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. --- - Continue in Harth (open this topic in the Harth agent): https://app.harth.build/agent?context=%2Fresources%2Fglossary%2Fnameplate-horsepower%2F - View this page in a browser: https://harth.build/resources/glossary/nameplate-horsepower/ - All resources for agents: https://harth.build/llms.txt