National Electrical Code Articles and Information
National Electrical Code Top Ten Tips: Article 406 -- Receptacles,
Cord Connectors, and Attachment Plugs
by Mark Lamendola
Based on the 2020 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 406 items we deem most important, based
on the pervasiveness of confusion and the potential costs of same.
- Donít dismiss receptacles 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
- If you use a receptacle with aluminum wiring, make sure it's marked CO/ALR.
Otherwise, don't use it [406.3(C)]. Where possible, replace the aluminum wiring.
- If you install a 3-wire (grounded) receptacle, you must ensure you have a
ground wire running to that receptacle. If you have a two-wire system, then
use GFCIs rather than regular receptacles [406.4]. GFCIs do not require a ground to operate. Any good GFCI comes with a sticker denoting a two-wire connection; affix that sticker. As with any GFCI installation, ensure you identify and correctly connect the Load and Line wires.
- Use a receptacle designed and rated for the voltage of the circuit in
which you are installing it. Ditto for attachment plugs. Receptacle and plug
configurations exist for a reason--they are supposed to "idiot proof" plugging
something into the correct voltage and wiring scheme (e.g., 4-wire vs.
- If your receptacle mounting box is set back from the finished surface,
mount the receptacle such that the mounting yoke or strap of the receptacle is
held rigidly to the finished surface [406.5(A)].
- If your receptacle mounting box is flush to the finished surface, mount
the receptacle such that the mounting yoke or strap of the receptacle is held
rigidly against the box or box cover [406.5(B)].
- Make sure that your receptacle faces are flush with (or project slightly
from) plastic faceplates (or other insulating face plates). If you use a metal
faceplate, your receptacle must project at least 0.4mm from the faceplate [406.5(D)].
- Don't install receptacles face-up in countertops [406.5(E)].
- If you install a 120V or 250V receptacle of 15A or 20A in a wet location,
the enclosure for that receptacle must be weatherproof. This doesn't mean only
when the cord isn't plugged in--the enclosure must protect the receptacle from
water even if that receptacle is in use [406.9(B)]. The actual wording is "...weatherproof whether or not the attachment plug cap is inserted...."
- You can't install a receptacle within or directly over a bathtub or shower
stall. It doesn't matter if that receptacle is a GFCI--don't put it in there! [4069.(C)].
The NEC has not moved past the typical 1960 home in terms of mandating receptacles, so builders typically put one receptacle in a bathroom because legally they can get away with that. This idiotic practice ignores the fact that people actually own and use electric shavers, dental irrigators, hair dryers, electric tweezers, and other grooming/hygiene products and may also want to set a boombox or radio in the room for when they are showering or engaging in other grooming activities. One reason people were installing receptacles over a tub or shower (and thus this rule was created) was the could tap into the wiring for the light that is there.
But the typical builder installs a bathroom receptacle on the same wall to which a vanity abuts. The obvious solution here is to go inside the vanity and cut a hole into the wall for a receptacle. You can fish wires down from the other receptacle. Now you have an additional receptacle. Another option is to replace the duplex with a quadplex, but that works only if you can replce the 2x4 box. Since the bathroom receptacle is a GFCI, you don't want to plug a multi-outlet device into and thus over it, since that will block the test and reset buttons. But you may find a suitable solution for adding more places to plug things in by touring the electrical aisle(s) of your local hardware store or home center. Keep in mind that whatever you have to plug in must sit somewhere and the vanity top usually is not suitable. You may need to install a shelf. If that's the case, you could simply install the shelf and mount a surge strip above or below it, powering that strip from the bathroom receptacle that's always been there.
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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