National Electrical Code Articles and Information

Code Quiz: Article 358

Based on the 2014 NEC

Questions and answers written by Mark Lamendola, who has worked as a master electrician, electrical inspector, and design engineer. Mark is an IEEE Senior Member, and the Code article author for Codebookcity.com. Since 1996, he has been writing National Electrical Code articles for electrical trade magazines and has an extensive portfolio of hundreds of NEC articles..

The Chapter Three Articles on wiring methods run in multiple series. Article 350 was the last in the sets of series about metallic conduits. Article 352 starts a series on nonmetallic conduits and after this series, a series of tubing starts with Article 358.

Article 358 provides the requirements for Electrical Metallic Tubing (EMT), by far the most popular type of raceway used in commercial applications. It's not the most popular for residential applications; Non-metallic sheathed cable (Article 334) holds that honor. Industrial facilities are also typically heavy users of EMT though in some types of plants you won't find it at all.

EMT is light and, because it assembles with pressure-type connectors, relatively easy to install. You'll need to set up your tubing bender (typically, a conduit bender with a tubing shoe) but you won't need a threader because EMT isn't threaded as conduits are.

Notice the distinction just made several times between tubing and conduit. EMT is not conduit. Many people mistakenly call it conduit, but that mistake can prove costly when trying to apply the NEC.

1. Article 358 is the twenty first in a series of Chapter 3 articles addressing specific wiring methods and the first one (of three) to address tubing. Which wiring method does it address, and what are its defining characteristics?
    

2. Name three permitted uses for this wiring method.
    

3. Name the prohibited uses for this wiring method.
    

4. What type hardware is permitted for supporting this wiring method?
    

5. What restriction is there on using couplings and connectors with this conduit?

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