Article 90 – Introduction
Properly placed at the beginning of the National Electrical Code, Article 90 is essential to correctly applying its requirements. The first thing it covers is the purpose of the code. Generally speaking this deals with safeguarding against fire and electric shock by installing and maintaining electrical systems free of hazards.
It’s also clear that the National Electrical Code is intended to be used by people who understand these hazards and are properly trained to safely deal with them. If you can’t identify what the hazard is and know how to limit or prevent it, then you have no business going any further.
Many people including some so-called experts argue over what the wording of an article actually says. These people clearly need training. If you know the articles intent then how it’s worded doesn’t really matter. If it could be better worded then request a change for consideration during the next code update cycle.
If you are using the wording of an article to bypass its intent, then you’re clearly unqualified to use the National Electrical Code.
Article 90 of the National Electrical Code also states exactly what is and isn’t covered in 90.2. This outlines the scope of its overall application.
Next up is 90.3 which is where many get turned around and misapply articles or believe some to be contradictory. This section explains the arrangement of the code sections and their relationship to one another.
90.3 identifies Chapters 1-4 as being general to all installations. Chapters 5, 6, and 7 supersede the general articles for special circumstances and can supplement or modify the general rules.
The limited energy and communications articles like Chapter 8 are standalone and the general rules only apply to them where they are specifically referenced.
Annexes and Informational Notes (FPN prior to 2011) are additional information and are not enforceable rules.
Lastly, let’s highlight 90.5. This article covers the terms that identify rules as either mandatory or permissive. If you have to do something or aren’t allowed to, it will say “shall” or “shall not”. If you can do something or don’t have to, it will say “shall be permitted” or “shall not be required”.
Often people mistake permissive rules that allow other options or methods as being additional requirements. They are not, they are normally used to allow alternate means to meet an intent. Again, if you knew the intent of what you are trying to accomplish in the first place that would’ve been clear.
The moral of this story is that if you know what you are doing, then your installations will be consistent with the intent of the National Electrical Code, but maybe not the words. If you don’t, you likely aren’t protecting anyone including yourself and should immediately seek training. You’re probably doing more than you need to sometimes and not enough others.