NEC Mistake

[Maxwell'sLaw]

Greetings, hope your doing well.
The reason I am contacting you:

I just saw the post on the topic of the "Mistake in the NEC" that Steven120volts recently put up; here's the link in case you want to review it:

91K views · 1.7K reactions | MISTAKE in the NEC!!!!!! | Stevenj120volts

MISTAKE in the NEC!!!!!!

www.facebook.com

Whilst I understand clearly what he is articulating, and while I have much respect for Steven120volts, as well as AnGry Sparky, and Paul Abernathy, in staying true to my philosophical tagline : "I am a seven footer chopped in half of a latino hillbilly, who's thirst for knowledge far exceeds my limitations",
I am concerned with how do we reconcile the wording of that particular article with the actual laws of physics regarding balanced forces and ampacity thresholds between the receptacle(s) as a unit which serves as a power supply bridge for energizing equipment, the conductors, and the OCPD?

I'd greatly appreciate it if you would kindly grace me with a few minutes or your time to enlighten me on this. In case you want to have a live conversation with me regarding this seemingly contradictory topic.

In the meantime, may Lord Almighty continue to bless you richly and immensely in countless ways each and every day.

 

[tortuga]

Nice video thanks for sharing, its not a mistake, section 210.21 deals with the minimum rating, its the floor section 406.4(E) deals with the interchangeability issue. It was inconsistent to have one rule for single receptacles, which always existed, and another rule for duplex.
I once ran across a NEMA 10-30 receptacle that had been installed on a 2-pole 15 on 14/3 wire in a basement. Since there were no other NEMA 14-30 receptacles in the building , and nothing plugged in no NEC violation existed. If someone plugged a 5500W clothes dryer in there would be a violation of the various articles that cover branch circuit load calculations, as you'd violate the load calc how 210.11, 220.10, 210.22, 210.18 etc.. interplay
I have also herd an argument that if a NEMA 14-50 is used for a 40A branch circuit it cannot be used for a 50A branch circuit.

 

[don_resqcapt19]

This is nothing more than a coordination issue between code sections that was not caught at the time the change to 210.21(B)(3) was made. It can be corrected by changing the reference in 406.12(A) [2026 code, 406.4(A) in the 2023 code]. The current reference is to Table 210.21(B)(3), but should have been changed to Section 210.21(B)(3) to avoid the conflict.
The installation of single receptacles having a rating greater than the rating of the branch circuit has been permitted for a very long time. The 2023 change in 210.21(B)(3) just applied that same rule to multiple receptacles on a branch circuit.
There is no hazard in either case as the branch circuit OCPD is sized to protect the circuit conductors and will open where the load exceeds what is permitted by the breaker time current curve.

 

[don_resqcapt19]

This has been in various forums, so I would expect a PI to either reverse the 2023 change in 210.21(B)(3) or one to remove "table" from 406.12(A) to be filed for the 2029 code.

 

[tortuga]

The way I read it 406.4(F) address limits receptacles interchangeability at a single premises, types of voltage / frequency and current I think 210 is more concerned with the minimum ratings in general. Interchangeability at a premises and minimum ratings are different issues, I think many AHJ's have local rules around that I have seen places that allow the same receptacles to be used for 208 and 240 for example a 6-30. Some clarification would be good for sure.

 

[don_resqcapt19]

The way I read it 406.4(F)

The issue is in 406.4(A), or in the 2023 code or 406.12(A) in the 2026.

406.12(A) Grounding Type.
Except as provided in 406.12(D), receptacles installed on 15- and 20-ampere 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, except as provided in 210.21(B)(1) for single receptacles or in Table 210.21(B)(2) and Table 210.21(B)(3) for two or more receptacles.

The language in 406.12(A) only references Table 210.21(B)(3) and the table limits you to 15 amp receptacles on a 15 amp circuit. By referencing only the table, you lose the language in the text of second level subdivision 210.21(B)(3).

210.21(B)(3) Receptacle Ratings.
Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall not be less than the values listed in Table 210.21(B)(3), or, where rated higher than 50 amperes, the receptacle rating shall not be less than the branch-circuit rating.

The language I have made bold in Section 210.21(B)(3) is the language that actually permits multiple receptacles with a rating greater that that of the branch circuit to be installed.

 

[tortuga]

Say I have a garage (premises) panel and I put in five two pole circuit breakers
15, 20, 30, 40 and 50A,
Then run I run five branch circuits to five individual receptacles and use a NEMA 14-50 for each, Article 210 is happy because the minimum ampacity of the receptacle is met:

Receptacle : Current
50A >= 15A
50A >= 20A
50A >= 30A
50A >=40A
50A = 50A​

406.4(F) says I need a unique configuration be used for each type of voltage frequency and current. Voltage is 120/240 frequency is 60 hz but the current is the issue.

 

[don_resqcapt19]

Say I have a garage (premises) panel and I put in five two pole circuit breakers
15, 20, 30, 40 and 50A,
Then run I run five branch circuits to five individual receptacles and use a NEMA 14-50 for each, Article 210 is happy because the minimum ampacity of the receptacle is met:

Receptacle : Current
50A >= 15A
50A >= 20A
50A >= 30A
50A >=40A
50A = 50A​

406.4(F) says I need a unique configuration be used for each type of voltage frequency and current. Voltage is 120/240 frequency is 60 hz but the current is the issue.

That section does not say amounts of current ....it says types of current.

406.12(F) Noninterchangeable Types.
Receptacles connected to circuits that have different voltages, frequencies, or types of current (ac or dc) on the same premises shall be of such design that the attachment plugs used on these circuits are not interchangeable.

 

[tortuga]

I figured thats your take on it, I interpret the parenthetical "(ac or dc)" to naturally expand the "types of current" to include AC types or DC types but does not limit the sub types of AC and DC current.

 

[don_resqcapt19]

I figured thats your take on it, I interpret the parenthetical "(ac or dc)" to naturally expand the "types of current" to include AC types or DC types but does not limit the sub types of AC and DC current.

Even without the parenthetical (ac or dc), there is no way to read that "types of current" is equal to "amount of current".
There was an intentional change between the 1999 and the 2002 codes.
In the 1999 code, receptacles were still in Article 410, and were placed into their own article 406 in the 2002 code.

410-56 (i) Noninterchangeability.
Receptacles, cord connectors, and attachment plugs shall be constructed so that receptacle or cord connectors will not accept an attachment plug with a different voltage or current rating than that for which the device is intended; however, a 20-ampere T-slot receptacle or cord connector shall be permitted to accept a 15-ampere attachment plug of the same voltage rating. Nongrounding-type receptacles and connectors shall not accept grounding-type attachment plugs.

That became 406.3(F) in the 2002 code and the current language first appeared in the 2002 code. If the 1999 language was still in the code, I would agree with you, but the code change was intentional between "current rating" and "types of current".
This will be another one where we will not agree.