Texas Electrician ExamTexas journeyman & master

Checked against primary sources 2026-08-24

The rating of a branch circuit comes from the overcurrent device

Get the direction right and a page of rules about permitted loads and receptacle ratings collapses into one lookup. Get it backwards and every one of those rules hands you a plausible wrong answer.

On this page
  1. The sentence the family hangs on
  2. How the rating gets decided in the first place
  3. What a circuit of a given rating may supply
  4. An individual branch circuit is a different animal
  5. Receptacle rating against circuit rating
  6. The maximum load rule, and the 125 percent that is not part of it
  7. Why the 80 percent shorthand is not a rule
  8. Reading the question
  9. What this page cites

The sentence the family hangs on

A branch circuit is rated at the maximum permitted ampere rating or setting of the overcurrent device protecting it. Not at the conductor, and not at the load. Article 210 says so in a short section near the front, and almost everything else in this subject area is a consequence of it.

So a 12 AWG conductor on a 15 ampere breaker is a 15 ampere circuit. What may be connected to it, which receptacles may sit on it, and how much continuous load it may carry all read off the device, not off the wire.

Candidates invert this constantly, and the reason is honest. The conductor is the thing physically carrying the current, so the conductor feels like the thing being rated. In the code the conductor sets a ceiling on which device you are allowed to install. Once the device is chosen, the device is the rating.

Upsizing a conductor for voltage drop is the clean test of whether you have it straight. Put a larger conductor on the same breaker and nothing about the circuit changes: not what it may supply, not the receptacles permitted on it, not the continuous load it can take. The device did not move, so the rating did not move.

How the rating gets decided in the first place

  1. Size the conductor for the load, correct it for ambient temperature and for conductor count, and compare the result against the termination limit.
  2. Find the largest standard device that conductor is permitted to have, applying the next higher standard rating permission at NEC 240.4(B) where its conditions are met.
  3. A conductor in the small sizes must not be given overcurrent protection above the limit in NEC 240.4(D), whatever the derating produced.
  4. The device you land on is the rating of the branch circuit. Write it in the margin before answering anything about loads.

The rating sits downstream of all the conductor arithmetic and upstream of everything about what may be connected. Items that read like two questions welded together usually are two questions welded together, and the seam is exactly here.

That is also why the order matters under a clock. Working the load question before you have the rating means holding two unknowns at once, and the second one is cheap to establish.

What a circuit of a given rating may supply

Article 210 sets out permitted loads by circuit rating, and knowing the shape of that section is worth more than remembering any one row of it.

The smaller ratings are general purpose. They feed lighting outlets, general use receptacles, and cord-and-plug-connected equipment, subject to a limit on how much of the circuit any single piece of that equipment is allowed to take.

The larger ratings are not general purpose, and the code narrows what may sit on them as the rating climbs. At the top of the range the permitted loads are few and named, and general use receptacles are not among them. An option that covers a large circuit in ordinary receptacles is there to be eliminated.

The clause candidates forget is the fraction. Where a circuit supplies both a cord-and-plug-connected piece of equipment and other loads, that one piece is limited to a share of the circuit rating rather than to the whole of it. Most appliance-on-a-circuit items turn on that sentence.

Read the section with a pencil once. It is a small matrix, and five minutes with it pays back more than almost anything else in Article 210.

An individual branch circuit is a different animal

A branch circuit supplying only one piece of utilization equipment is an individual branch circuit, and the restrictions written for circuits with more than one outlet do not reach it.

That is why the same appliance can be the wrong answer on one circuit and the right answer on another circuit of identical rating. The phrase doing the work is in the stem, not in the numbers: supplies only, or individual branch circuit.

Skimming past that phrase is how a candidate answers the wrong question perfectly. When the stem describes what a circuit feeds, read it twice before reading the options once.

Receptacle rating against circuit rating

A single receptacle installed on an individual branch circuit has an ampere rating not less than the rating of the circuit. One receptacle on its own circuit can be asked for the whole thing, so it has to be able to take the whole thing.

Where a circuit has more than one receptacle on it, a receptacle rated below the circuit rating is allowed, and the permitted pairings sit in a short table in Article 210. The reasoning is diversity. Two receptacles are unlikely to be loaded to the full circuit rating at the same instant, and neither of them is the entire circuit.

The trap is a definition rather than a rule. A single receptacle is one contact device on its own yoke. The duplex you install without thinking is two receptacles, so a duplex on an individual branch circuit is not a single receptacle and the first rule above never applied to it.

Items get written on that distinction on purpose, because it separates candidates who read Article 100 from candidates who assumed they already knew what the words meant. If a stem is careful enough to say single receptacle rather than receptacle, it is careful for a reason.

The maximum load rule, and the 125 percent that is not part of it

The ceiling on what a branch circuit may actually carry lives in the load calculation article rather than in Article 210.

The total load on a branch circuit shall not exceed the rating of the branch circuit nor the maximum loads specified in 120.11(A) through 120.11(C).

NEC 120.11, 2026 edition

That is a limit on the load. It is not the continuous load rule, and the two get fused together so often that the 2026 edition added a sentence to keep them apart.

NEC 120.5(E) is new in the 2026 book, and it is titled Percent Multiplier. Under NEC 120.5(E) a load calculation is not required to carry continuous loads at 125 percent. The informational note under it gives the reason in plain terms: calling a load continuous drives the size of the conductor and the size of the overcurrent device, which is a different question from how many volt-amperes the installation draws.

So there are two questions and they have two homes. How much load is there is answered in Article 120. What the copper and the breaker have to survive is answered in Article 210, and that is where the 125 percent for continuous loads has always lived. Reading an item for which of those it asks takes a second and decides the section you open.

Why the 80 percent shorthand is not a rule

It is arithmetic that somebody turned into a slogan. One divided by eight tenths is one and a quarter, so where every ampere on a circuit is continuous, holding the load to 80 percent of the device gives the same size as raising the device to 125 percent of the load.

Put one noncontinuous ampere on that circuit and the two stop agreeing. The code adds the noncontinuous load at its full value and applies the increase only to the continuous portion (NEC 210.19). There is no general rule holding a branch circuit to 80 percent of its rating, and the 80 percent limit that does appear in Article 210 is aimed at one piece of cord-and-plug-connected equipment rather than at the circuit.

The case that costs points is the circuit with no continuous load on it at all. The total load on that circuit is allowed to reach the rating of the circuit (NEC 120.11), and a candidate carrying 80 percent as a rule will mark a perfectly good installation as overloaded, or size the conductor a step high and find that answer waiting on the list.

Carry the code's own direction instead. The increase is something you do to the conductor and the device, not something you do to the load, and it applies to the part of the load that runs for three hours or more.

Note where the maximum load sentence lives, because it is a navigation problem as much as a knowledge one. Before the 2026 edition the load calculation article was Article 220, over in Chapter 2. It is Article 120 now, at the front of Chapter 1, and the section numbers inside it moved with it. A candidate hunting for a maximum load rule under branch circuits, or under a 220 number remembered from an older book, will burn a minute and find nothing.

Reading the question

The required dwelling circuits, the receptacle spacing rules and the load calculation all sit on top of this one idea, and none of them behaves while the rating is coming from the wrong place. If you fix one thing in this subject area before test day, fix the direction.

What this page cites

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Every rule here is cited to the section it comes from, and corrections are logged in public with the date. This is study material rather than electrical advice, and it does not replace your own code book or your inspector.