Nec 210.23 B 1-2 equipment ampacity limit on a circuit

[Rick 0920]

If only one piece of equipment is plugged in how does that duplex change the definition?

It doesn't. The definition is vague, as are numerous sections of the NEC. Art. 210.70 (A)(1) says that in habitable rooms, the switch shall be located "NEAR" the entrance to the room on the wall. What's near to me may not be near to you. IMO, both points are valid.

 

[pipe_bender]

If a receptacle is present and open for use it demonstrates the intent of the electrical contractor, It communicates to the user 'go ahead plug something in' this is a general purpose circuit.

 

[wwhitney]

The definition is vague

It really isn't. If you have a refrigerator that says in its instructions that it requires an individual branch circuit, and the branch circuit has only a single receptacle outlet at which a duplex receptacle is installed, and is located behind the refrigerator as is typical, then it would be ridiculous to say that's a 110.3(B) violation because it's not an individual branch circuit.

Likewise, you could install an individual branch circuit for a compressor with a 6-15 plug on it, and put multiple 6-15 receptacles on the branch circuit around your garage, so you can roll the compressor around to various locations. That's still an individual branch circuit, despite the multiple receptacles, as the circuit is designed to only supply one piece of utilization equipment. [Maybe welder and 6-30 or 6-50 would be a better example.]

Cheers, Wayne

 

[Rick 0920]

If a receptacle is present and open for use it demonstrates the intent of the electrical contractor, It communicates to the user 'go ahead plug something in' this is a general purpose circuit.

I agree. But does the NEC reference that? It does not. It is a vague definition that leaves it open to different interpretations.

 

[pipe_bender]

It really isn't. If you have a refrigerator that says in its instructions that it requires an individual branch circuit, and the branch circuit has only a single receptacle outlet at which a duplex receptacle is installed, and is located behind the refrigerator as is typical, then it would be ridiculous to say that's a 110.3(B) violation because it's not an individual branch circuit.

Likewise, you could install an individual branch circuit for a compressor with a 6-15 plug on it, and put multiple 6-15 receptacles on the branch circuit around your garage, so you can roll the compressor around to various locations. That's still an individual branch circuit, despite the multiple receptacles, as the circuit is designed to only supply one piece of utilization equipment. [Maybe welder and 6-30 or 6-50 would be a better example.]

Cheers, Wayne

Have you actually done that and passed an inspection?

 

[Jpflex]

The one time we got red tagged for it was over two decades ago I had wired a GFCI for a sump pump off a general purpose circuit and the motor in question did not have 'separate' overload protection, we pushed back a little but since there are other practical reasons for individual circuits like redundancy, and having to calculate the load on a residential branch circuit leads to post modern looking geometry diagrams dividing up the square footage of rooms served based on the number of general purpose circuits, its simpler to run individual circuits.

I have encountered this a lot in my last job. Many compressor motors over 1 hp but no separate overload protection, only branch circuit OCPD

 

[tortuga]

I agree. But does the NEC reference that? It does not. It is a vague definition that leaves it open to different interpretations.

The definition of 'Individual branch circuit' was added to the 1956 NEC and if you look at the commentary in the handbooks from back then they intend a single receptacle if a receptacle is employed.

The verb used is "supplies", present tense.

For the 2002 code one of the most prolific and legendary public input authors Dan Leaf submitted a Public Input (PI) to clarify the definition of branch circuit general-purpose includes a branch circuit that supplies just one outlet with a duplex receptacle, and the CMP agreed and that definition is clear:

SUBMITTER: Dan Leaf, Palmdale, CA
RECOMMENDATION: Revise:
A branch circuit that supplies a number of two or more
receptacles or outlets for lighting and appliances.
SUBSTANTIATION: Editorial. The phrase "number of outlets" is
presumed to mean more than one, although one is a number.
Present wording does not cover a circuit with one outlet box
containing more than one receptacle, or one outlet box containing
one or more receptacles and from which a permanent connection is
made, since there is still only one outlet.
PANEL ACTION: Accept.

So if you have a outlet with only one duplex receptacle on a branch circuit that meets the definition of general purpose branch circuit.

Likewise, you could install an individual branch circuit for a compressor with a 6-15 plug on it, and put multiple 6-15 receptacles on the branch circuit around your garage, so you can roll the compressor around to various locations.

That meets the definition of general purpose branch circuit, so the rules for general purpose branch circuit prevail.

 

[wwhitney]

That meets the definition of general purpose branch circuit, so the rules for general purpose branch circuit prevail.

All you have done is demonstrate that the definitions of Branch Circuit, General Purpose and Branch Circuit, Individual are not mutually exclusive.

Note that 210.21(B)(1) refers to the case of a "single receptacle on an individual branch circuit." This is not needless redundancy, but reflects that an individual branch circuit may have more than one receptacle on it.

Cheers, Wayne

 

[tortuga]

All you have done is demonstrate that the definitions of Branch Circuit, General Purpose and Branch Circuit, Individual are not mutually exclusive.

Note that 210.21(B)(1) refers to the case of a "single receptacle on an individual branch circuit." This is not needless redundancy, but reflects that an individual branch circuit may have more than one receptacle on it.

Right I am glad we agree as soon as a circuit has more than one receptacle it meets the definition of general purpose branch circuit.
Then we can also probably agree that

Whichever is stricter will control any particular install.

 

[wwhitney]

Then we can also probably agree that "Whichever is stricter will control any particular install."

Yes, although in my example of the multiple 30A receptacles on an individual branch circuit for a compressor, it seems a regrettable consequence that the compressor is now limited to 80% of the branch circuit rating, rather than 100%, per 210.21(B)(2).

Interestingly, as Table 210.21(B)(2) only goes up to 30A, that would not apply to a 40A or 50A circuit. I'm not clear on why 30A circuits are included in Table 210.21(B)(2); seems like the table could be restricted to NEMA 5-15 and NEMA 5-20 receptacles.

Although 210.23(B) imposes a similar maximum of 80% for cord-and-plug connected utilization equipment. Seems like all of the references to "branch circuit supplying two or more outlets or receptacles" in 210.21-210.23 should be changed to the "other than individual branch circuits" wording as used in 210.18.

Cheers, Wayne

 

[wwhitney]

P.S. Just noticed that Public Input No. 1344-NFPA 70-2023 proposed changing the definition of "individual branch circuit" to "A branch circuit that supplies only a single outlet utilization equipment is connected to." The CMP rejected the change with the statement "An individual branch circuit is a branch circuit that supplies only one utilization equipment, and it is not necessary that only one outlet exist as long as the individual branch circuit is serving only one utilization equipment."

So again, no problem with a duplex receptacle on an individual branch circuit, or multiple outlets for that matter.

 

[wwhitney]

Although 210.23(B) imposes a similar maximum of 80% for cord-and-plug connected utilization equipment.

This should further say "for 30A branch circuits." So just amending 210.21(B)(2) would not be enough.

Cheers, Wayne

 

[tortuga]

Yes, although in my example of the multiple 30A receptacles on an individual branch circuit for a compressor, it seems a regrettable consequence that the compressor is now limited to 80% of the branch circuit rating, rather than 100%, per 210.21(B)(2).

Yeah JP was asking about the 80% limit on receptacles, the only way I see around that for 30A or less is if it does not qualify as a general purpose branch circuit.

Interestingly, as Table 210.21(B)(2) only goes up to 30A, that would not apply to a 40A or 50A circuit. I'm not clear on why 30A circuits are included in Table 210.21(B)(2)

Evidence suggests that receptacles are really designed to carry no more than 80% of their rating. I would lean more the other way and add 40A and 50A receptacles to that.
The NEC could add a 210.100 'construction specifications' and make a classification of heavy duty receptacles that are designed for continuous loads and 100% of the branch circuit rating, kinda like what is happening with EV receptacles. (but there is no actual standard for them)