--- title: The NEMA Numbering System description: Interpower Explains the NEMA Numbering System image: https://blog.interpower.com/hubfs/Interpower_March2018/Images/NEMA_5-15P_drawing.png --- [![Interpower Facebook](https://blog.interpower.com/hubfs/Interpower_March2018/Images/facebook-button-black.png "Interpower Facebook")](https://www.facebook.com/interpowercorporation) [![Interpower LinkedIn](https://blog.interpower.com/hubfs/Interpower_March2018/Images/linkedin-button-black.png "Interpower LinkedIn")](https://www.linkedin.com/company/interpower-corporation) [![Interpower Twitter](https://blog.interpower.com/hubfs/Interpower_March2018/Images/twitter-button-black.png "Interpower Twitter")](https://twitter.com/interpowergroup) **PHONE:U.S.** [(641) 673-5000 |](tel:6416735000) **Toll Free:** [(800) 662-2290 |](tel:8006622290) **UK** [+44 (0)1908 295300 |](tel:+4401908295300) **Freephone:**[00800 5566 5566](tel:0080055665566) [![Interpower](https://blog.interpower.com/hubfs/Interpower_March2018/Images/IC-white-site-heading.png "Interpower") ![Interpower](https://blog.interpower.com/hubfs/Interpower_March2018/Images/mobile-logo.png "Interpower")](http://interpower.com) - 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[Why observe international product safety requirements?](http://www.interpower.com/ic/designers/designing-for-export/Why-Observe-International-Product-Safety-Requirements.html) - [Conforming to Local Safety Requirements](http://www.interpower.com/ic/designers/designing-for-export/Conforming-to-Local-Safety-Requirements.html) - [What standards must electronic or electrical equipment meet?](http://www.interpower.com/ic/designers/designing-for-export/What-Standards-Must-Electronic-or-Electrical-Equipment-Meet.html) - [European & International Standards Writing Agencies](http://www.interpower.com/ic/designers/designing-for-export/european-international-standards-writing-agencies.html) - [What is the CE Marking?](http://www.interpower.com/ic/designers/designing-for-export/What-is-the-CE-Marking.html) - [What is the ENEC Mark?](http://www.interpower.com/ic/designers/designing-for-export/What-is-the-ENEC-Mark.html) - [Who enforces international safety standards?](http://www.interpower.com/ic/designers/designing-for-export/who-enforces-international-safety-standards.html) - 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[Heat Shrink Tubing](http://www.interpower.com/ic/designers/in-depth-product-line-information/more-information-on-heat-shrink-tubing.html) - [Plugs and Sockets](http://www.interpower.com/ic/designers/in-depth-product-line-information/More-info-on-Plugs-and-Sockets.html) - [High Power Pin & Sleeve Devices](http://www.interpower.com/ic/designers/in-depth-product-line-information/More-Information-on-High-Power-Pin-and-Sleeve-Devices.html) - [Connector Locks](http://www.interpower.com/ic/designers/in-depth-product-line-information/More-information-on-Connector-Locks.html) - [Cable](http://www.interpower.com/ic/designers/in-depth-product-line-information/More-Information-on-Cable.html) - [Odd Sizes in AWG Flexible Cable](http://www.interpower.com/ic/designers/in-depth-product-line-information/odd-sizes-in-AWG-flexible-cable.html) - [Strain Reliefs](http://www.interpower.com/ic/designers/in-depth-product-line-information/More-Information-on-Strain-Reliefs-Cable-Glands.html) - [Terminal Blocks](http://www.interpower.com/ic/designers/in-depth-product-line-information/More-Information-on-Terminal-Blocks.html) - 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[Tweet](https://twitter.com/share) NEMA (National Electrical Manufacturers Association) has a variety of standards for electrical manufacturers. This is so that consistency and safety can be achieved. A numbering system has been created to standardize the description and rating of NEMA plug and socket patterns. The NEMA pattern and numbering system consists of four main identifiers. ## First Identifier The first identifier can be blank or have the letter “L.” This determines whether the device will use straight or locking blades. ## Second Identifier The second identifier is a number which determines the voltage rating. For example: - “1” identifies that the configuration is rated for 125VAC, Class II - “5” identifies that the configuration is rated for 125VAC, Class I - “6” identifies that the configuration is rated for 250VAC, Class I The rating given is the highest voltage allowed for use with the device by the standard, ANSI/NEMA WD-6. In a Class I application, the component must have the ability to provide grounding. In a Class II application, no grounding is required. ## Third Identifier The third identifier is also a number. This specifies the amperage rating. The amperage rating, like the voltage rating, is the highest amperage allowed for use with the device by the standard. ## Fourth Identifier The fourth identifier is a letter. “P” stands for a plug and “R” stands for a receptacle (also referred to as an outlet or a socket). ## Examples 1-15R is a 125V, Class II, 15-amp receptacle L5-20P is a locking, 125V, Class I, 20-amp plug 6-15P is a 250V, Class I, 15-amp plug ## NEMA Plug Patterns | ![The NEMA Numbering System](https://blog.interpower.com/hs-fs/hubfs/Interpower_March2018/Images/NEMA_1-15P_drawing.png?width=130&height=130&name=NEMA_1-15P_drawing.png) NEMA 1-15P | ![The NEMA Numbering System](https://blog.interpower.com/hs-fs/hubfs/Interpower_March2018/Images/NEMA_1-15P_drawing.png?width=130&height=130&name=NEMA_1-15P_drawing.png) NEMA L1-15P |   |   | | --- | --- | --- | --- | | ![The NEMA Numbering System](https://blog.interpower.com/hs-fs/hubfs/Interpower_March2018/Images/NEMA_5-15P_drawing.png?width=130&height=130&name=NEMA_5-15P_drawing.png) NEMA 5-15P | ![The NEMA Numbering System](https://blog.interpower.com/hs-fs/hubfs/Interpower_March2018/Images/NEMA_L5-15P_drawing.png?width=130&height=130&name=NEMA_L5-15P_drawing.png) NEMA L5-15P | ![The NEMA Numbering System](https://blog.interpower.com/hs-fs/hubfs/Interpower_March2018/Images/NEMA_5-20P_drawing.png?width=130&height=130&name=NEMA_5-20P_drawing.png) NEMA 5-20P | ![The NEMA Numbering System](https://blog.interpower.com/hs-fs/hubfs/Interpower_March2018/Images/NEMA_L5-20P_drawing.png?width=130&height=130&name=NEMA_L5-20P_drawing.png) NEMA L5-20P | | ![The NEMA Numbering System](https://blog.interpower.com/hs-fs/hubfs/Interpower_March2018/Images/NEMA_6-15P_drawing.png?width=130&height=130&name=NEMA_6-15P_drawing.png) NEMA 6-15P | ![The NEMA Numbering System](https://blog.interpower.com/hs-fs/hubfs/Interpower_March2018/Images/NEMA_L6-15P_drawing.png?width=130&height=130&name=NEMA_L6-15P_drawing.png) NEMA L6-15P | ![The NEMA Numbering System](https://blog.interpower.com/hs-fs/hubfs/Interpower_March2018/Images/NEMA_6-20P_drawing.png?width=130&height=130&name=NEMA_6-20P_drawing.png) NEMA 6-20P | ![The NEMA Numbering System](https://blog.interpower.com/hs-fs/hubfs/Interpower_March2018/Images/NEMA_L6-20_non-polarized.png?width=130&height=130&name=NEMA_L6-20_non-polarized.png) NEMA L6-20P | ## NEMA Nomenclature Chart For a detailed listing of the NEMA numbering system, please see the NEMA Nomenclature chart below. [![NEMA Nomenclature Chart](https://blog.interpower.com/hubfs/Interpower_March2018/Images/nema-nomenclature-chart.png)](http://www.interpower.com/ic/designers/designing-for-export/guides-and-charts/nema-nomenclature-guide.html) Other resources to consult include the [North American Non-Locking NEMA Configurations](http://www.interpower.com/ic/designers/designing-for-export/guides-and-charts/North-American-Nonlocking-NEMA-Configurations.html) and [Connect to North America](https://blog.interpower.com/hubfs/Interpower_March2018/Docs/NEMA-w-cable-poster.pdf). Interpower offers free technical support. For further assistance, please see Interpower’s contact information below. **Source:** ANSI/NEMA WD-6 ## Stay In-The-Know with *InfoPower* The monthly *InfoPower* blogs are created to assist you in designing, building, and maintaining products for worldwide markets by providing you with information on topics relevant to power system components. ### Subscribe to Email Updates ### Recent Posts ### Posts by Topic ## [InfoPower Archive](http://www.interpower.com/ic/infopower-archive.html) ### United States 100 Interpower Ave Oskaloosa, IA 52577 | [info@interpower.com](mailto:info@interpower.com) Toll-Free Phone: (800) 662-2290 | Toll-Free Fax: (800) 645-5360 Phone: (641) 673-5000 | Fax: (641) 673-5100 ### United Kingdom 10 Kelvin Drive | Knowlhill, Milton Keynes | Buckinghamshire, MK5 8NH | UK | [uk@interpower.com](mailto:uk@interpower.com) **UK, Ireland, Germany, Switzerland, Austria** Freephone: 00800 5566 5566 | Freefax: 00800 5655 5655 **International:** Phone: +44 (0)1908 295 300 | Fax: +44 (0)1908 295301 © 2026 Interpower. 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