Branch Circuit Ratings Practice Questions

B. The maximum permitted ampere rating or setting of the overcurrent device protecting it

The rating section says the circuit takes the maximum permitted ampere rating or setting of the device, and it adds that where conductors of higher ampacity are used for any reason, the device still determines the rating. So a 12 AWG conductor on a 15 ampere breaker is a 15 ampere circuit. The conductor feels like the thing being rated because it carries the current, which is exactly why candidates invert this.

NEC 2026 210.18

A. 25 amperes

The list runs 10, 15, 20, 30, 40 and 50 amperes, so 25 is missing from it even though 25 is a perfectly standard overcurrent device rating. Standard device ratings and permitted branch circuit ratings are two different lists that overlap without matching. An individual branch circuit is not held to this list at all.

NEC 2026 210.18, Table 240.6(A)

D. It stays at the rating of the overcurrent device

Upsizing a conductor is the clean test of whether you have the direction straight. The device did not move, so the rating did not move, and nothing about what the circuit may supply, which receptacles may sit on it or how much continuous load it may carry changes either. The conductor sets a ceiling on which device you are allowed to install; once the device is chosen, the device is the rating.

NEC 2026 210.18

C. Any load for which it is rated

A branch circuit supplying only one piece of utilization equipment is an individual branch circuit, and the permissible load rules written for multiple outlet circuits do not reach it. One exception exists: a 10 ampere individual branch circuit is not permitted to supply receptacle outlets. The phrase doing the work is in the stem rather than in the numbers, so read for supplies only or individual before reading the options.

NEC 2026 210.22, Article 100

A. Nonlighting outlet loads only

The permitted loads narrow as the rating climbs, and above 50 amperes the circuit is limited to nonlighting outlet loads. One exception opens multioutlet circuits above 50 amperes to nonlighting loads where maintenance and supervision keep servicing in qualified hands. An option that covers a large circuit in ordinary receptacles is there to be eliminated.

NEC 2026 210.23(E)

B. 16 amperes

The rating of any one cord and plug connected piece of equipment not fastened in place is held to 80 percent of the circuit rating, and 80 percent of 20 is 16 amperes. This is the 80 percent that actually exists in Article 210, and it is aimed at one piece of equipment rather than at the circuit as a whole. The 12 amperes is the receptacle load limit from a different table.

NEC 2026 210.23(B)(1)

C. 10 amperes

Where lighting units or cord and plug connected equipment not fastened in place are also on the circuit, the total rating of equipment fastened in place other than luminaires is held to 50 percent of the circuit rating, so 10 amperes here. Two different percentages live in the same subsection, one for a single portable item at 80 percent and one for the fastened in place total at 50 percent. Which one applies turns on what else is sharing the circuit.

NEC 2026 210.23(B)(2)

D. 24 amperes

The 30 ampere subsection holds any one cord and plug connected item to 80 percent of the circuit rating, and 80 percent of 30 is 24 amperes. That circuit is also limited to fixed lighting units with heavy duty lampholders in other than dwelling units, or utilization equipment in any occupancy. Reaching for the whole 30 ignores the percentage, and the 15 and 20 come from the smaller circuit sizes.

NEC 2026 210.23(C)

B. Lighting outlets, and dwelling unit exhaust fans on bathroom and laundry room lighting circuits

The 10 ampere circuit is the newest rating in the list and it is narrowly written: lighting outlets, plus dwelling unit exhaust fans on bathroom and laundry room lighting circuits. Separate sentences say that a 10 ampere branch circuit does not supply receptacle outlets, and that a 10 ampere individual branch circuit does not either. Anything about receptacles on a 10 ampere circuit is a wrong answer.

NEC 2026 210.23(A), 210.18, 210.22

A. Not less than the rating of the branch circuit

One receptacle on its own circuit can be asked for the whole circuit, so it has to be able to take the whole circuit. Where a circuit has more than one receptacle on it the pairings come from a short table instead, and a receptacle rated below the circuit is allowed, because two receptacles are unlikely to be loaded to the full rating at the same instant. The rule and the exception are decided by a definition rather than by arithmetic.

NEC 2026 210.21(B)(1)

C. No, a duplex is two contact devices on one yoke, so it is a multiple receptacle

Article 100 defines a single receptacle as one contact device with no other contact device on the same yoke, and a multiple receptacle as two or more on the same yoke. The duplex you install without thinking is two receptacles, so the single receptacle rule never applied to it. Items get written on this distinction on purpose, because it separates candidates who read the definitions from candidates who assumed they knew what the words meant.

NEC 2026 Article 100, 210.21(B)(1)

D. 15 or 20 amperes

The receptacle rating table pairs a 15 ampere circuit with 15 ampere receptacles, a 20 ampere circuit with 15 or 20, a 30 with 30, a 40 with 40 or 50, and a 50 with 50. Above 50 amperes the receptacle rating is not less than the branch circuit rating. Reading the 20 ampere row as 20 only is the common slip, and it is the reason the duplex 15 ampere receptacle on a 20 ampere circuit keeps getting questioned in the field.

NEC 2026 Table 210.21(B)(3)

A. 12 amperes

The maximum load table reads by circuit rating and receptacle rating together: a 15 ampere receptacle on a 15 or 20 ampere circuit is held to 12 amperes, a 20 ampere receptacle on a 20 ampere circuit to 16, and a 30 ampere receptacle on a 30 ampere circuit to 24. It is the receptacle rating rather than the circuit rating that picks the row here. Reading the circuit rating first gives you the 16.

NEC 2026 Table 210.21(B)(2)

B. 45 amperes and 45 amperes

Both rules run the same sum: the noncontinuous load at its full value plus 125 percent of the continuous load, which is 10 plus 35, or 45 amperes. Forty five is a standard rating, so the device lands there, and the conductor takes the larger of that 45 and the 38 ampere maximum load, which is also 45. Adding the two loads without the multiplier gives the 38, and multiplying the whole 38 by 1.25 gives the 47.5.

NEC 2026 210.19(A)(1), 210.20(A), Table 240.6(A)

D. The device rating may be the sum of the continuous and the noncontinuous loads

Both the conductor sizing section and the overcurrent protection section carry the same exception: where the assembly including the device is listed for 100 percent operation, the value is the plain sum of the two loads with no multiplier. It is the assembly that has to be listed, not just the breaker. The 80 percent is not what the exception says anywhere, it is the reciprocal a candidate substitutes from habit.

NEC 2026 210.20(A), 210.19(A)(1)

C. In the load calculation article, at the maximum load section

The maximum load sentence lives in the load calculation article, and it caps the total load against the rating of the branch circuit and against the maximum loads set out in its own subdivisions. Before the 2026 edition that article was Article 220 over in Chapter 2, and it is Article 120 at the front of Chapter 1 now. A candidate hunting for a maximum load rule under branch circuits, or under a 220 number remembered from an older book, burns a minute and finds nothing.

NEC 2026 120.11

B. Up to the rating of the branch circuit

There is no general rule holding a branch circuit to 80 percent of its rating. The 80 percent shorthand is arithmetic somebody turned into a slogan, because one divided by eight tenths is one and a quarter, and the two only agree where every ampere on the circuit is continuous. A candidate carrying 80 percent as a rule will mark a perfectly good installation as overloaded, and there is usually an option waiting for that.

NEC 2026 120.11

A. A load calculation is not required to carry continuous loads at 125 percent

The percent multiplier sentence is new in this edition, and it exists to keep the maximum load question apart from the continuous load question. Its informational note gives the reason plainly: continuous duty drives the size of the conductor and the device, which is a different question from how many volt-amperes the installation draws. It does not remove the multiplier from the sections that size conductors and overcurrent devices.

NEC 2026 120.5(E)

C. No, the next higher standard rating selected cannot exceed 800 amperes

The next size up permission carries three conditions and all of them have to be met: the conductors are not part of a branch circuit supplying more than one receptacle for cord and plug connected portable loads, the ampacity does not correspond to a standard rating, and the next higher standard rating selected does not exceed 800 amperes. Above that ceiling a separate subsection takes over and requires the conductor ampacity to equal or exceed the device rating. The restricted access wording belongs to adjustable trip breakers in the same section, which is why it reads plausibly.

NEC 2026 240.4(B), 240.4(C), Table 240.6(A)

D. 15 amperes

The small conductor list gives 15 amperes for 12 AWG aluminum and copper-clad aluminum, 20 for 12 AWG copper, 15 for 14 AWG copper, 25 for 10 AWG aluminum and 30 for 10 AWG copper. Reading the copper row for an aluminum conductor is the whole of the error, and it gives you the 20. Every one of those caps applies after any correction for ambient and any adjustment for conductor count.

NEC 2026 240.4(D)

B. In the outlet devices section of Article 210

The overcurrent protection section for branch circuits points four ways at once: conductors go to 240.4, flexible cords and fixture wires to 240.5, equipment to whatever article covers it, and outlet devices to the outlet devices section in the same article. That last pointer is what brings the receptacle and lampholder rules into the device sizing question. Items that read like two questions welded together usually are, and this pointer is one of the seams.

NEC 2026 210.20(D), 210.21

C. A heavy duty type lampholder

Above 20 amperes the lampholder is of the heavy duty type, and the section defines that by wattage: not less than 660 watts for the admedium type, or not less than 750 watts for any other type. The permitted load rules pick this up again, since the larger circuits that may feed lighting at all are limited to fixed lighting units with heavy duty lampholders in other than dwelling units. Material and guarding are not what this rule turns on.

NEC 2026 210.21(A)

A. 40 amperes

The conductor sizing section for household cooking appliances sets a floor of 40 amperes for a range rated 8-3/4 kW or more, alongside the general requirement that the conductors carry the maximum load to be served. It is a stated minimum rather than a calculated one, so the arithmetic on the nameplate does not lower it. The 50 amperes is the common installed size, which is why it sits in the choices.

NEC 2026 210.19(C)

D. 70 percent of the branch circuit rating, and not smaller than 10 AWG

The exception permits the smaller neutral where the maximum demand of a range rated 8-3/4 kW or more has been calculated from Column C of the cooking equipment demand table, and it then sets two floors at once: an ampacity of at least 70 percent of the branch circuit rating, and a size no smaller than 10 AWG. Both have to be satisfied, so the larger of the two governs. Remembering one floor and forgetting the other is what produces every wrong answer here.

NEC 2026 210.19(C)

C. 3 hours or more

Three hours is the figure, and it is a definition rather than a rule, which is why it decides items in several different articles at once. A load that runs for three hours or more moves the conductor and the overcurrent device by a quarter, and it does not move the calculated load. Reading a stem for how long something runs is the fastest way to know which sections you are about to open.

NEC 2026 Article 100