Texas Electrician ExamTexas journeyman & master

Checked against primary sources 2026-08-24

The 125 percent lands on two things, and a third can take it back

Three hours of maximum current is the whole test for whether a load is continuous. Everything that costs points happens after that.

On this page
  1. What makes a load continuous
  2. The multiplier lands in two places
  3. The exception that takes the multiplier off
  4. Then the terminations can take it back
  5. The rule that appears to say the opposite
  6. The order that produces the right answer
  7. What this page cites

What makes a load continuous

Duration, and nothing else. Article 100 defines a continuous load as one where the maximum current is expected to continue for three hours or more.

It says nothing about what the equipment is or how important it is. Parking lot lighting on a photocell qualifies. A large motor that runs twenty minutes at a time does not. The same fixture can be continuous in a warehouse aisle and not continuous in a supply closet, because the test lands on the installation rather than on the catalog page.

Exam stems flag it in more than one way. Some say continuous outright. Some hand you an operating schedule and wait to see whether you do the arithmetic. Some describe an occupancy, a store open from nine until nine, and leave the inference to you.

Watch for the motor. A motor branch circuit gets its own 125 percent out of Article 430, computed from a table current rather than from the nameplate, and the trigger is a continuous duty application rather than three hours at maximum current (NEC 430.22). Those are two different tests wearing one number. A motor that runs half a minute at a time is still a continuous duty application unless the machine it drives cannot be run continuously under load at all, and a motor in short-time, intermittent, periodic or varying duty leaves 430.22 for a duty-cycle table instead. Answering a motor question with the continuous load rule is a wrong answer that arrives at a plausible size.

The multiplier lands in two places

The conductor and the overcurrent device both take it. A branch-circuit conductor supplying a continuous load must have an allowable ampacity of not less than the noncontinuous load plus 125 percent of the continuous load (NEC 210.19). The next section along says the same thing about the rating of the device ahead of it, in almost the same words and with the same exception attached.

Wrong-answer sets are built on the half answer. One option raises the conductor and leaves the device sitting at the load. Another raises the device and leaves the conductor. Both look like work has been done, which is exactly why they are there. If an option moves only one of the two, it is a distractor.

The reason both move is that both sit in the heat. A conductor carrying its rated current for three hours has reached its steady temperature and stays there, and so have the lugs it lands on and the device those lugs are part of. Loading a device to 125 percent of the load is the same relationship as loading it to 80 percent of its rating, and what the margin buys is headroom for the higher temperature inside an enclosure. It is taken at the design stage instead of being hoped for in service.

The exception that takes the multiplier off

Where the assembly, including the overcurrent device, is listed for operation at 100 percent of its rating, the increase comes off and the plain load governs.

Read that permission carefully, because it attaches to the assembly and not to the breaker on its own. A device marked for continuous duty in a panel that carries no such listing does not get you there. The listing names the enclosure the device was evaluated in, which is the practical reason you cannot create one by dropping a breaker into a panel you already own.

On an exam it behaves as a switch. If the stem tells you the assembly is listed for continuous operation at its full rating, use the plain load. If the stem is silent, use the multiplier. Candidates who have never seen this equipment on a job sometimes read the sentence as a distractor and ignore it. It is the answer key.

Then the terminations can take it back

A circuit is rated at its lowest rated part, and that part is usually a screw A conductor with a ninety degree rated insulation runs between a breaker rated seventy five degrees and a lug rated sixty degrees. The ampacity you are allowed to use is read from the sixty degree column, because the sixty degree lug is the lowest rated component in the path. The ninety degree column is still used, but only as the starting point for adjustment and correction, never as the final answer. breakerrated 75° lugrated 60° conductor insulation rated 90° lowest rating governs: 60° start at the 90° column for adjustment and correction, then check the result against the 60° column and take the lower two ratings in the path, one of them decides
The insulation rating is where you start correcting. The terminal rating is where you have to end up. Drawn against NEC 110.14(C) and 310.14(A)(2). Ampacities are in Table 310.16, in your book.

The 125 percent gives you a target ampacity. It does not tell you which temperature column to find that ampacity in, and that is a separate decision made by the equipment at each end of the run.

Article 110 states the termination limit as a temperature rating rather than as an ampere value. So the target and the limit are computed from different places and then compared, and whichever produces the smaller conductor wins.

Here is the shape of it. The figures below are invented for the example. None of them is read out of a code table, and the two you would look up in your own book are named rather than printed.

  1. A lighting load of 48 amperes runs from open to close. A receptacle load of 22 amperes does not.
  2. The continuous portion at 125 percent is 60 amperes. Add the whole 22 and the target is 82 amperes.
  3. That 82 is the minimum for the conductor and the minimum for the overcurrent device, both.
  4. If the equipment at both ends is limited to the 75 degree rating, the conductor has to reach 82 amperes in the 75 degree column of the ampacity table.
  5. A 90 degree insulation does not move that. It gives you room to derate before you hit the ceiling, and the ceiling stays where the lugs put it.

If the raceway is hot or crowded on top of all that, the correction and adjustment factors are applied to the ampacity at the insulation rating, and the derated result is compared against the termination value. Take the lower. The 125 percent takes no part in that comparison. It set the target the comparison has to clear.

Two limits, computed apart, then compared. People who know both rules still lose this one, because the two limits arrive at different moments in a question and it is tempting to answer as soon as the first of them produces a number that looks like a conductor size.

The rule that appears to say the opposite

One line at the front of the load calculation article settles an argument that ran in both directions for years.

Load calculations shall not require continuous loads to be calculated at 125 percent.

NEC 120.5(E), 2026 edition

That answers a different question from the one this page has been answering. A load calculation asks how much load a building has. Conductor sizing asks what the copper and the breaker have to live through. The multiplier belongs to the second question, and 120.5(E) is saying the first question is not where the code demands it.

Candidates who meet that subsection before they meet the conductor sections come away thinking the increase has been withdrawn. It has not. It is held out of a place it was never supposed to be doing work, because taking it in the load calculation and again at the conductor inflates every continuous portion of a service by a quarter.

Sorting an item by which question it asks takes a second. Calculated load, service load or feeder load in the stem puts you in Article 120. Minimum conductor size, minimum ampacity or the rating of an overcurrent device puts you in a sizing rule, and the multiplier is live in every one of them.

Then sort a second time, by what is being sized, because the sizing rules are spread across three articles and only one of them is Article 210. Branch circuit conductors and branch circuit devices are Article 210. Feeder conductors and the feeder device are the feeder article. Service-entrance conductors and the service device are the service article. Each states the same 125 percent in its own words, so the arithmetic never changes and the citation does. That is enough to lose an item when the options are section numbers, which on this subject they often are.

The load calculation article has not stopped using the figure altogether. NEC 120.11(A) applies 125 percent to the largest motor load where motors and other loads share a circuit. Read that subsection and 120.5(E) back to back once and the line between them stops moving around.

The order that produces the right answer

  1. Decide whether the load is continuous. Three hours of maximum current, and nothing else.
  2. Add 125 percent of the continuous load to the whole of the noncontinuous load. Hold that number.
  3. Check whether the stem gives you an assembly listed for operation at its full rating. If it does, drop back to the plain load.
  4. Size the overcurrent device at or above the held number, taking the first of the standard ratings in NEC 240.6(A) that does not fall below it.
  5. Size the conductor to reach the held number in the column the terminations allow, after applying any ambient and conductor count factors to the ampacity at the insulation rating.
  6. If the conductor is one of the small sizes, apply the cap in NEC 240.4(D) last. It only ever cuts.

One permission gets dragged into step four that does not live there. NEC 240.4(B) lets an overcurrent device sit at the next standard rating above the ampacity of the conductor it protects. That is a rule about protecting a conductor, not a rule for rounding a calculated load, and it carries three conditions that all have to hold. The one nobody remembers rules the permission out where the conductors are part of a branch circuit supplying more than one receptacle for cord-and-plug-connected portable loads. In step four the device rating starts at the held number and goes up, never down.

Steps two and five carry the points. Two is the rule everybody studies. Five is the reason a correctly applied rule still produces the wrong conductor, and it is the step that gets skipped when the clock is the thing you are watching.

One note in the margin of your own book is worth the ink: the number from step two is a minimum, and it is the minimum for the conductor and for the device alike. It is not itself a standard device rating and it is not a load. Writing that down once stops it being compared against the wrong thing later in the same question.

What this page cites

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