Every wiring method has its own article, and they all answer the same six questions
Learn the six questions once and you can navigate an article you have never opened.
On this page
The pattern every Chapter 3 article follows
Chapter 3 gives each wiring method its own article, and those articles are structured almost identically.
- Where it is permitted to be used.
- Where its use is restricted, which is a separate list from the permitted one.
- Size limits, minimum and maximum.
- Support and securing intervals.
- Bends, and how many between pull points.
- Termination and fittings.
Once you know that, an unfamiliar article stops being intimidating. You are looking for one of six things and they appear in roughly that order.
The uses permitted and uses not permitted pairing
Almost every method article has a permitted section immediately followed by a not permitted section.
Read both. A question describing an installation is nearly always answered by one of those two lists, and the not permitted list is the one that gets skipped.
The distinction usually turns on exposure: damp, wet, corrosive, subject to physical damage, direct burial, or embedded in concrete.
Support intervals are the mechanical answer
Each method article gives a distance at which the wiring is supported and a shorter distance within which it is secured after a box or fitting.
Those two numbers are different and they are asked about separately. Securing near a termination is a shorter distance than the general support interval.
These live in the article for that method, not in a general table, which is why a question naming the method is pointing you at an article rather than a chapter.
How to navigate under time pressure
Identify the method the question names. Go to its article. Ask which of the six questions is being asked. Read that section.
Do not try to hold support intervals for a dozen methods in your head. The book has them and you are permitted to use it.
What is worth holding is the article number for the common methods, because that is the lookup that costs you time.
What this page cites
- NEC 300.6 Protection against physical damage, which applies across methods.
- NEC 314.16 Box fill, which pairs with any wiring method question involving a box.