Wiring Methods And Materials

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WIRING METHODS AND MATERIALS

Chapter 2 provided the general rules for wiring and protection of conductors, and was primarily concerned with the correct sizing of circuits and the means of protecting them. This differs from the purpose of Chapter 3, which is to correctly install the conductors that make up those circuits.

Chapter 2 was a bit of an uphill climb, because many rules had a kind of abstract quality to them. Chapter 3, on the other hand, gets very specifi c about conductors, cables, boxes, raceways, and fi ttings. It’s also highly detailed about the installation and restrictions involved with wiring methods.

It’s because of that detail that many people incorrectly apply the Chapter 3 wiring methods rules. Be sure to pay careful attention to the details, rather than making the mistake of glossing over something. This is especially true when it comes to applying the Tables.
The type of wiring method you’ll use depends on several factors: Code requirements, the environment, need, and cost are among them.

Power quality is a major concern today. The cost of poor power quality runs into the millions of dollars each month in the United States alone. Grounding and bonding defi ciencies (refer back to Article 250) constitute the number one cause of power quality problems. Violations of the Chapter 3 wiring methods rules constitute the number two cause of power quality problems. Code violations can also lead to fi re, shock, and other hazards. This is particularly true of Chapter 3 violations. Chapter 3 is really a modular assembly of articles, each detailing a specifi c area of an electrical installation. It starts with wiring methods [Article 300], covers conductors [Article 310], and then enclosures [Articles 312 and 314]. The next series [Articles 320 through 340] addresses specifi c types of cables, with Articles 342 through 390 covering specifi c types of raceways. We close with Article 392, a support system, and the last string [Articles 394 through 398] for open wiring.

Notice as you read through the various wiring methods that, for the most part, the section numbering remains the same in each article. This makes it very easy to locate specifi c requirements in a particular article. For example, the rules for securing and supporting can be found in 3xx.30 of each article. In addition to this, you’ll fi nd a “uses permitted” and “uses not permitted” section in nearly every article.