Understanding the National Electric Code is crucial to building safe, successful solar projects. But sometimes it can be difficult to interpret. What kind of source material goes into the NEC anyway, and how do standards come out of it?
Marvin R. Hamon
I saw a great presentation that provided some answers to these questions at Solar Power International 2016. The speaker, Marvin R. Hamon, P.E., principal at Hamon Engineering, has been involved with renewable energy since the late 1970s, and participated in creating each edition of the NEC since 2005. He did a nice job of explaining how to read the NEC, how to access and use source material from the NEC version update process to interpret the NEC, and how NEC interpretations become industry standards.
Here are five things I learned that may be interesting to you too.
1. NEC development is headed and published by the National Fire Protection Association (NFPA). It’s been adopted in all 50 states (but not by law) and serves as the benchmark for safe electrical design, installation and inspection to protect people and property from electrical hazards. The NEC addresses the installation of electrical conductors, equipment and raceways; signaling and communications conductors, equipment and raceways; and optical fiber cables and raceways in commercial, residential, and industrial sectors.
2. The NEC is published every three years. Though headed by the NFPA, it’s completely volunteer based any any individual can contribute. Some people form or join working groups to contribute to the NEC collectively. The first edition was published in 1897, the current edition is 2014 and so the next edition will be 2017. The code is adopted in most states within a couple of years.
3. Anyone or any group can recommend proposals or changes to the code in between editions. Sometimes these proposals are made into tentative interim amendments to the code. Suggesting a proposal is as easy as filling out a form, but you must include a “substantiation” of why you want to make the addition or change so that your intention is clear. NFPA then publishes all proposals online and it’s open to, as Hamon said, “public harassment,” or open to comments from everyone. Everyone, “fights it out in a sausage making party,” again as Hamon eloquently, but probably accurately, puts it. Hamon said eventually a single interpretation tends to “bubble up to the top” and is adopted as a industry standard.
4. As you may imagine, the resulting code ends up not being so straight forward. Hamon likens it to a kind of legal document open to interpretation. The same code paragraph can mean different things to different people. The code development process also results in poor wording, even with proofreading errors. To help make things a little clearer there’s an NEC style manual, which serves as a guide to how words and style are used in the NEC (because they may not be the words you would use in every day conversations), what words you can’t use and even how articles are numbered, etc.
5. There are resources outside of the NEC to help interpret it by asking questions, and getting feedback. These include online forums like Mike Holt’s code forum and RE-wrenches’ email list.
6. Article 690, the solar part of the code, has the most changes every year because we’re in such a fast-paced industry. Meanwhile, areas like transformers may not have changes in 20 or 30 years.
7. The NEC is typically adopted by states and municipalities as they try to standardize their enforcement of safe electrical practices. But in some cases it may be amended, altered and or even rejected in lieu of regional regulations voted on by local governments. Group trainers, professional associations and publications serve as teachers to AHJs.
8. The NEC doesn’t define standards; UL does. For example, the NEC may say there must be arc-fault detection but not which devices to use. UL then determines qualifications and creates a specification that is given to products that meet its requirements.