National Electrical Code Articles and Information
National Electrical Code Top Ten Tips: Article 404 -- Switches
by Mark Lamendola
Based on the 2017 NEC
Please note, we do quote from copyrighted material. While the NFPA
does allow such quotes, it does so only for the purposes of education
regarding the National Electrical Code. This article is not a substitute
for the NEC.
These are the 10 NEC Article 404 items we deem most important, based
on the pervasiveness of confusion and the potential costs of same.
- Donít dismiss switches as not deserving your
attention. There's a reason why the NEC has finally devoted an entire
Article to them. Even the trade magazines, such as EC&M, are writing about
- You must wire switches such that you are switching only the ungrounded
(hot) conductor [404.2(B)]. Don't switch the neutral or the ground.
- Put switches in enclosures listed for such a use [404.3(A)]. Putting a switch in an
enclosure that is not listed for use as a switch enclosure puts you at risk
for liability, and puts the switch users at risk of injury to property and
- Don't run other wiring through switch enclosures [404.3(B)]. These enclosures have
one purpose: to act as switch enclosures. They are not pullboxes, junction
boxes, or raceways.
- If you put a switch in a wet location, use an enclosure rated for wet
locations . Don't use a GFCI as a license to violate this rule. A GFCI is not
intended to overcome all problems that may arise from putting a switch in an
enclosure not rated for the intended use.
- Mount switches such that gravity won't close them [404.6]. That means "OFF" is
down and "ON" is up.
- If you are grouping or ganging switches, arrange them so they are
operating at similar voltages [404.8]. The NEC requirement is that the voltage
differential not be more than 300V, unless you accommodate the difference by
placing such switches in their own enclosures.
- Faceplates must completely cover the opening in which a switch is mounted [404.9].
- You can use general-use dimmer switches only for the control of
permanently installed incandescent luminaires, unless they are listed for
other loads and you install them per manufacturer's directions [404.14(E)].
- You must observe the wire-bending space requirements of 404.3 and Table
How the NEC is arranged
- The first four Chapters of the NEC apply to all installations.
- Article 90 precedes Chapter One, and establishes the authority of the NEC.
- Article 80 follows the body of the NEC; it exists as Annex H. It provides the requirements for administration.
- Chapters 5, 6, and 7 are the "special" chapters, covering special: occupancies, equipment, and conditions (in that order).
- Chapter 8 provides the requirements for communications systems.
- Chapter 9 provides tables.
- The appendices provide mostly reference information.
- Appendix D contains examples that every NEC user should study.
Try your NEC moxy:
- Do you know the difference between bonding and grounding? Hint: Look in the NEC, Article 100.
- Does the NEC refer to grounding incorrectly in any of its articles? Yes! So be careful to apply the Article 100 definitions. Don't ground where you should bond.
- When doing motor load calculations, which Article covers hermetic motors? Answer: While Article 440 covers the application of hermetic motors, it does so only by amending Article 430 because hermetic motors are a special case of motors. For motor load calculations, refer to Article 430.
- Does the NEC provide a voltage drop requirement? Yes! It does so in a special case, which is Article 648 Sensitive Electronic Equipment. But for general applications, it does not provide a requirement; it merely provides a recommendation in a couple of FPNs.
- Take our Code Quizzes.
Remember other applicable codes, rules, standards, and references:
- OSHA's electrical worker safety rules.
- IEEE standards.
- NETA standards.
- NFPA standards.
- International Codes (if applicable to the installation).
- State Codes (if the state has them).
- Local ordinances and permit requirements.
- Local fire codes.
- Manufacturer requirements or guidelines.
- Customer security requirements.
- Industry standards.
- Your company's own internal standards, practices, and procedures.
- Engineering drawing notes.
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