This is the second article in a series on learning how to find our way through the National Electrical Code. These articles are aimed at providing insight into how the NEC is often taught to those just getting into the trade. After all, the Code is not meant to be an instruction manual for untrained people. 

Last month, I wrote about how the overall layout of the NEC spans nine chapters laid out by common themes. In this article, I dive a little deeper into what takes place once we have pinpointed the overall area we should be searching in.

Here’s a brief recap. The NEC chapters are organized by whether they apply generally to all installations or to special scenarios. Once you understand whether your inquiry fits into one of those buckets, or potentially both, then you can narrow it down further. Are you in the planning/layout stage, building or using electricity stage? Does your question involve special locations, equipment or conditions? Or are you installing communications systems? Once you answer these important questions, you can get a better sense of where to look.

Ask the right questions

So, this is where we find ourselves. We dug in and determined what chapter in the NEC we need to search in. However, this doesn’t have to be a search for a needle in a chapter haystack. This is where the NEC article comes into the picture. 

Take Chapter 2, for instance. We identified it as being where to find requirements for the planning and layout of electrical systems from a generalized viewpoint. This means that Chapter 2 applies to all installations unless modified by an article in chapters 5, 6 or 7. 

Chapter 2 includes 10 different articles, many of which are well over 100 pages long. If we just stopped after getting to Chapter 2, we would be stuck combing through hundreds of pages to find the right section.

So, what article do we look in? Staying with our example of Chapter 2, we need to look at what part of the installation we are planning or laying out. Is it a branch circuit? Maybe a feeder? Are we looking to calculate the capacity of the electrical system we need to install? Or maybe our question involves grounding and bonding, the ever popular topic. And—new for 2023—if your question involves an installation above 1,000V, there is also an article for that.

If we ask the right questions, it should be relatively easy to determine what article to explore. However, keep in mind that we might need to look in multiple articles to find the answer. For example, if we are determining what size branch circuit to install to feed the new EV charging stations at a hospital, we might need to look in Article 625 for supply requirements of electric vehicle supply equipment. We also might need to look in Article 517 for healthcare facilities to see if there are any special requirements. We will certainly need to look in articles 210 and 220 for guidance.

Article dissection

But we aren’t done once we know what article to access. Now we get to dissect the anatomy of the article to understand where exactly to look for the answer. Articles are broken up further into parts that organize the requirements even more by certain characteristics. 

Take Article 230 as an example. This article covers the requirements for services and is broken up into several parts such as overhead service conductors, underground service conductors, service-entrance conductors and the service disconnecting means, just to name a few. We can understand what part of Article 230 we need to be in once we know what part of the service we are dealing with. 

Although services are tricky, as there are so many terms for conductors and other service equipment, we might need to brush up on our definitions. This just means a quick trip into Article 100, because a recent change in the NEC Style Manual has put all NEC and NFPA 70E definitions into Article 100, even those specific to a single article.

Look in the proper section

Once we know the part of the article to look in, it is simply a matter of finding the proper section for the specific question. Over the years there have been several revisions to the Code aimed at helping us find the correct section and make the usability of the NEC easier for those trying to find the answer. 

Maybe the most notable usability feature is the standardization of the numbering system throughout the Chapter 3 articles. This was done to allow the user to always find the same type of information in the same section of the article regardless of the specific wiring method. For instance, if the wiring method is a raceway, you will find the requirement for number of conductors in that raceway in 3XX.22. Likewise, securing and supporting requirements will be found in 3XX.30 and listing requirements in 3XX.6. Other notable standardized sections:

The first section of every article will be the scope statement for that article (e.g., 110.1, 334.1, 430.1)

If other specific articles apply, it will typically be called out in the third section (e.g., 240.3, 425.3, 800.3).

If an article contains “uses permitted” or “uses not permitted,” these requirements will be found in the tenth and twelfth sections (e.g., 242.12, 334.10, 400.12).

Once we have a solid understanding of how to apply this methodology to finding our place in the NEC, there really is no subject we can’t find the answer to. 

There will, however, be times when the confusing part will be understanding what is being asked. This is always the toughest part of using the NEC. Do you understand the question to begin with? 

Most frustration with navigating the Code stems from this misunderstanding. It is easy when the question is as straightforward as, “How many conductors am I permitted to install in a trade size ¾-inch EMT?” But sometimes the question is a bit more ambiguous, such as, “What size conductors do I need on the secondary side of a 75-kVA transformer?” Questions like this take a bit more legwork.

Next month’s article will explore what it takes to drill down and answer tough or ambiguous questions like the last one. We’ll also look at a couple of other tools that exist in the NEC to help us know where to go on our quest to answer those burning questions we need answered. 

Until next time, stay safe and remember to always test before you touch.

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