Statement of Problem and Substantiation for Public Input
This public input, along with the others I am providing, is a direct consequence of my investigation of a fire in a GFCI receptacle mounted on the outside of my house which could have been catastrophic, but thankfully wasn’t. I am a licensed engineer. A detailed report was prepared. The existing Table 210.21(B)(3) has an entry for “not over 15” and an entry for “40 or 50,” both under the column heading “Receptacle Rating.” There are no NEMA blade configurations for receptacles rated less than 15 amps or for 40 amp receptacles. The existing table by showing “not over 15” suggests that receptacles less than 15 amps are acceptable. This understanding is not correct. In addition, 406.3(B) specifically states that receptacles shall be rated not less than 15 amps. Receptacles rated 50 amps shall be limited to 50 amp circuits. In general, the ampacity of receptacles should correspond with the ampacity of circuits. A receptacle undersized for the circuit can become a safety problem through overloading which doesn’t trip the circuit breaker, while a receptacle oversized for the circuit can result in nuisance tripping which could result in a safety problem in terms of operation of equipment, or at least an inconvenience. The unique problem of 15 amp receptacles on a 20 amp circuit is addressed separately in another public input I am making but for the purposes of matching receptacles with circuits, it is necessary that the rating of a receptacle correspond with the blade configuration of the receptacle. However, this does not prevent a NEMA 5-15R receptacle, for example, from having an appropriate internal design to allow placement in a 20 amp circuit with full protection from a 20 amp breaker. The usual method of circuit sizing is to determine load, then the wire size based on the sum of the non-continuous load and 125% of continuous load (with consideration for adjustment factors). Then the breaker size is selected to match wire size, except the breaker size can be bumped up to the next standard size if the calculated breaker size would otherwise fall between two standard sizes. Therefore, it should follow that the receptacle size is chosen first, and then the circuit size matched accordingly. It is understood that accepted practice often determines the number of receptacles that are known to be workable for a particular circuit rating. This approach is often the determining factor for use of 20 amp circuits with 15 amp receptacles, the approach the existing table takes. A line for a 60 amp receptacle, with a 60 amp circuit rating, was added to complete the listing of the available amperage ratings of receptacles in accordance with NEMA blade configurations. It is acknowledged that Part II. Branch Circuit Ratings, 210.18 Rating., specifically recognizes 15, 20, 30, 40, and 50 amp branch circuits. The new table proposed eliminates the problem of having no receptacle rating available for a 40 amp circuit. Lastly, the present table Table 210.21(B)(3) duplicates information presented in Table 210.24 and therefore it is redundant.
Committee Statement
The text in the table has been modified to match existing receptacles that are available. The title of the table has been changed to make it clear that this table applies to circuits with more than one receptacle or receptacle outlet as the parent language of the table states.[/quote
There was a Public Comment for the 2026 that would have fixed this, but the second draft meeting minutes show this as reject so it would not have gone to the formal written ballot. The reject statement in the meeting minutes said:
Insufficient substantiation was provided to required receptacle ratings to conform to Table 210.21(B)(3). The branch circuit should be
protected by the proper sized OCPD.
