Another handy Article in the National Electrical Code (NEC) every electrical apprentice must master is Art. 406, which covers a few basic rules to remember, such as receptacle rating requirements, receptacle type selection, cord connectors, and attachment plugs (cord caps). It contains important guidelines to keep in mind as you begin installing and replacing receptacles in various environments like the subset of assembly occupancies described in Art. 518, which includes, but is not limited to:
- Dormitories
- Auditoriums
- Skating rinks
- Gymnasiums
- Wet locations
- Dwelling units
- Damp locations
- Child care facilities
- Places of awaiting transportation
- Preschools and elementary education facilities
- Guest rooms and guest suites of hotels and motels
- Business offices, corridors, waiting rooms and the like
- Clinics, medical and dental offices, and outpatient facilities
Mastering NEC technical terms
On your continued quest to navigate (and ultimately master) the NEC, always pay attention to key terms listed in the Definitions section of Art. 100 (2023 edition of the Code). It’s important that you familiarize yourself with “technical terms” used in the Code book to become more adept in its language; you’ll reap the benefits of this habit long term.
Here are some important terms you’ll need to know that specifically apply to Art. 406:
Child Care Facility. A building or structure, or portion thereof, for educational, supervisory, or personal care services for more than four children seven years old or less. (Note: This is an example of a term that prompts readers to identify the specific type of receptacles required in a designated special occupancy type that requires tamper-proof receptacles.)
Outlet Box Hood. This was a new term added in the 2017 edition. A housing shield intended to fit over a face‐ plate for flush-mounted wiring devices or an integral component of an outlet box or of a faceplate for flush-mounted wiring devices. The hood does not serve to complete the electrical enclosure; it reduces the risk of water coming in contact with electrical components within the hood, such as attachment plugs, current taps, surge protective devices, direct plug-in transformer units, or wiring devices.
Attachment Plug (Plug Cap) (Plug). A device that, by insertion in a receptacle, establishes a connection between the conductors of the attached flexible cord and the conductors connected permanently to the receptacle. Eventually, you may work in a variety of building types and ages. This may include retail stores, commercial buildings with older wiring, and newly constructed or existing residential homes (dwelling units).
Make sure any receptacle replacements match the circuit rating (voltage and load rating requirements) and building wiring methods. These requirements are listed in Sec. 406.3 (A)(B)(C) Receptacle Rating and Type and Receptacles for Aluminum Conductors. Always make sure the receptacle is listed and marked with the manufacturer’s name or identification and voltage and ampere ratings. Receptacles and cord connectors shall be rated not less than 15A, 125V, or 15A, 250V, and shall be of a type not suitable for use as lampholders. For buildings, equipment, or older homes with aluminum wiring (knob and tube), always make sure the receptacle is identified to be used with aluminum conductors. Receptacles rated 20A or less and designed for the direct connection of aluminum conductors shall be marked CO/ALR.
Always pay attention to Informational Notes
Hidden under Sec. 406.3 (B) is a requirement from Art. 210 in Sec. 210.21(B) for Single Receptacle(s) on an individual branch circuit. A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit., Informational notes become important because they give us additional pertinent information regarding the section and part just read, or it’s an expansion or further interpretation on what you just read; this is helpful with subject matters you may not be familiar with.
Article 406 also lists installation and location requirements for:
- Floor receptacles
- Controlled receptacles
- Grounding type receptacles
- Isolated ground receptacles
- Receptacle with USB charger
- Tamper-resistant receptacles
- Non-grounding type receptacles
- Generated mounted receptacles
- AFCI protection on receptacle circuits
- Receptacles in damp or wet locations
- Weather resistant and GFCI receptacles
General installation guidelines for receptacles in Sec. 406.4 (A)
Receptacles installed on 15A and 20A branch circuits shall be of the grounding type. Grounding-type receptacles shall be installed only on circuits of the voltage class and current for which they are rated. There are exceptions to this rule provided in Table 210.21(B)(2) and Table 210.21(B)(3). The handiest of these two tables is 210.21(B)(3) Receptacle Ratings for Various Size Circuits. This permits electricians to install 15A- or 20A-rated receptacles on a 20A circuit. Note: Please leave a comment in the box below with your opinion on why the NEC permits us to do this. This table is often referenced on licensing exams, so highlight this in your Code book — it may come in handy in the future.
Installing non-grounding-type receptacles
There are several rules you should begin to remember in replacing “non-grounding type” receptacles as discussed in Sec. 406.4 (D)(2)(a), Sec. 406.4 (D)(2)(b), and Sec. 406.4 (D)(2)(c). Keep in mind:
- A non-grounding-type receptacle(s) shall be permitted to be replaced with another non–grounding-type receptacle(s).
- A non-grounding-type receptacle(s) shall be permitted to be replaced with a (GFCI) ground-fault circuit interrupter-receptacle(s). When you use this method, remember you must apply a “No Equipment Ground” label on the cover plates for these receptacles.
In case you’re wondering, the equipment grounding conductor “shall not be connected” from the ground-fault circuit-interrupter-type receptacle to any outlet supplied from the ground-fault circuit-interrupter receptacle. But beware if you need to use this method, there are two important informational notes under Sec. 406.4 (D)(2)(c), which state some equipment or appliance manufacturers require that the branch circuit to the equipment or appliance includes an equipment grounding conductor. Informational Note No. 2: See Sec. 250.114 for a list of cord- and plug-connected equipment or appliances that require an equipment grounding conductor. Here are just a few to remember for residential occupancies: ranges, freezers, refrigerators, air conditioners, kitchen waste disposers, information technology equipment, sump pumps and electrical aquarium equipment, clothes-washing, clothes-drying, and dish-washing machines.
Follow my column for more practical how-to articles and tips for applying electric basics concepts in the field. Past columns include Everyday Instructions for Electricians, The Apprentices Guide to Special Equipment, The Apprentice’s Intro Guide to Motors, The Apprentice’s Guide to Service Entrance Cable, The Apprentice’s Guide to NEC Art. 382, and The Apprentice’s Guide to NEC Art. 550. For more information on why a structured approach is so important to navigating the NEC and how to put its requirements into practice in real-world settings, read “The NEC for Newbies.”
Harold De Loach, a master electrician and electrical trainer/instructor, is the founder of The Academy of Industrial Arts (www.taia-school.com) in Philadelphia. With more than 30 years of experience in the field, he writes regular exclusive content for the E-Train and can be reached at [email protected].
