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National Electrical Code Top Ten Tips: Article 406 -- Receptacles, Cord Connectors, and Attachment Plugs

by Mark Lamendola

Based on the 2023 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.

  1. Donít dismiss receptacles as not deserving your attention. There's a reason why the NEC finally devoted an entire Article to them with the 2020 revision. Even the trade magazines, such as EC&M, are writing about receptacles.
  2. If you use a receptacle with aluminum wiring, make sure the receptacle is marked CO/ALR. Otherwise, don't use it [406.3(C)]. Where possible, replace the aluminum wiring.
  3. 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.
  4. 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. 3-wire).
  5. 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)].
  6. 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)].
  7. 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)].
  8. This requirement was removed with the 2023 revision: "Don't install receptacles face-up in countertops [406.5(E)]." Now 406.5(E) says receptacles installed in counterops must be listed for countertops. You still do not want them face-up, because what happens if someone knocks over a glass of water or bowl of soup into that receptacle?
  9. 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...." With the 2023 revision, the hinged covers of outlet box hoods must be able to open at least 90 degrees (or fully open if the cover isn't designed to be at 90 from closed position to open position).
  10. 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! [406.9(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 replace the 2x4 box unless you obtain a 4 or 6 outlet receptacle that is designed to be installed in a 2x4 box; the face of it sticks out from the wall for obvious reasons.

    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.

    Perhaps some day, the typical home builder will design a bathroom with the novel concept that whoever occupies that home might also want to use the bathroom without pretending it's 1950. Built-in cabinets with LED lighting, UV lamps, and receptacles added to them would be a good start. Electric razor, electric toothbrush, electric manscaper, curling iron, hair dryer, space heater, flosser, electric hair clippers, etc. tend to be in most modern bathrooms. Having a receptacle for the electric mop (to keep the linoleum clean) and a vacuum cleaner (since a vacuum cleaner receptacle was stupidly left out of the hallway where it's needed) would also be nice. And a bidet power source will probably be an NEC requirement some day, why not be ahead of that?