The termination check runs on a number the derating never touched, and it settles more items than the derating does

How the exam asks about terminations

Sixteen of the 68 conductor sizing questions in our bank put the termination check in front of you, and 10 of the 68 name a temperature column outright. The check travels as well. It turns up in conduit items where the conductor size drives a fill, in grounding items where the conductor material matters, and on the knowledge portion as a plain question about what fixes a circuit's usable ampacity.

The calculations shape is a pair of numbers. A stem hands you a derated ampacity and a column ampacity and asks which one you may use. Four options come back: the derated figure, the column figure, their average and their sum. Half the option list exists because a candidate holding two numbers with a clock running reaches for an operation.

The knowledge shape drops the arithmetic and describes equipment. There the item turns on the circuit rating, on a marking at the terminals, or on whether the equipment is listed and identified for a higher rating. PSI gives the journeyman knowledge portion 130 minutes for 59 items, about 2.2 minutes each, against 110 minutes for 26 calculations items at about 4.2 minutes each, so a column question you have to reason out from scratch costs you double its share of the clock.

Two triggers, and either one decides

110.14(C)(1) splits at 100 amperes, and each side of the split carries two independent triggers joined by the word or. That single conjunction is what the items are built on.

• Circuits rated 100 amperes or less, along with equipment marked for 14 AWG through 1 AWG conductors, default to the 60 degree column.
• Circuits rated over 100 amperes, along with equipment marked for conductors larger than 1 AWG, default to the 75 degree column.

So the terminal marking is a way into the rule all by itself, and it can override the reading you would have taken from the ampere rating. A 60 ampere disconnect whose lugs are marked for conductors larger than 1 AWG lands on the 75 degree side on the marking alone. When a stem tells you what the terminals are marked for, that sentence is a trigger doing work.

One bank item runs the plain version. A circuit is rated 90 amperes, the conductors carry a 90 degree insulation, and the equipment carries no marking permitting a higher rated conductor. The answer comes out of the 60 degree column, and the trap line on the most attractive wrong option records the reasoning exactly: a candidate read the absence of a marking as freedom from the default, when the absence of a marking is what puts you in the default.

What a 90 degree insulation actually buys

The opening of 110.14(C) permits a conductor with a higher temperature rating to be used for ampacity correction, for adjustment, or for both. That is the whole practical value of the higher rating, and it is a real value: you start from a bigger number and the correction and adjustment factors eat into that bigger number before anything else does. In a hot roof or a full raceway it is often the difference between one trade size and the next.

It buys nothing at all where there is no derating to do. Three conductors at the table's own ambient landing on 75 degree lugs get the 75 degree figure whether the insulation is rated 75 or 90, and the extra rating has done no work on that run.

Our bank asks this directly. A stem says a candidate was told to size from the 90 degree column and then check the result against the 60 degree column, and asks what the 90 degree column is being used for. The answer is that it is the starting point for correction and adjustment. The most attractive wrong option treats it as the final ampacity, which is the exact error the termination check exists to catch.

Two limits, and the four options

The conductor ampacity and the termination limit are separate tests on the same conductor. One is the table figure from the insulation column with every applicable factor multiplied through it. The other is the table figure from the column 110.14(C) chose, read clean. The conductor is held to the smaller of the two.

The reverse mistake shows up just as often and it is quieter. A candidate applies both factors to the termination column, producing a number smaller than the code asks for. That oversizes the conductor, so it reads as a safe error and it is still the wrong answer, and an option list with four plausible sizes in it will be carrying that answer.

The lowest rated part can sit mid-run

110.14(C) coordinates the ampacity to the lowest rated component in the current path, and the path includes conductors, terminations and devices between the two ends. Candidates check both ends and stop.

Our bank has the item built for that habit. A run uses 90 degree conductors landing on 90 degree lugs, and one splice in the middle is made with a connector listed for 75 degrees C. The 75 degree column governs the whole run. The trap line on the first wrong option records the reasoning that gets people there, which is that a splice somehow sits outside the rule, and the rule reaches any listed connector in the path.

110.14(C)(2) is the route by which a genuinely higher termination becomes available. A pressure connector bought and installed separately from the equipment carries its own listing, and the conductor may be used at an ampacity no greater than that connector is listed for. That makes a 90 degree termination a question about a listing on a specific part, which is a different question from what the wire jacket says.

A stamp and a listing are different things

A temperature number cast near a terminal does not by itself move you up a column. The permission in the section attaches to equipment listed and identified for use with conductors of that rating, so the evidence is the listing and the instructions that come with the equipment. Most ordinary breakers, panelboards and safety switches are 75 degree equipment at best, and a great deal of small equipment stays at 60 degrees whatever insulation you feed it with.

On a paper this arrives as a stem that names a 90 degree insulation type and then describes perfectly ordinary equipment. Nothing in it says listed and identified, so nothing in it opens the 90 degree column, and an option offering that column is there for the candidate who read the jacket and stopped.

One option under 110.14(C)(1) hardly anybody has read: for motors marked with design letter B, C or D, conductors rated 75 degrees or higher are permitted with the ampacity held to the 75 degree value. A motor stem that names a design letter is pointing at that option, and motor circuit items are where you will meet it.

What it costs to get wrong

A conductor that pencils out and then fails inspection usually failed here. The installer sized from the 90 degree column because the wire was THHN, and the gear was 75 degree gear. The repair is a larger conductor or different equipment, since a larger conductor has a larger ampacity in the termination column too, while a hotter insulation letter on the same size of wire leaves that column figure exactly where it was.

On a paralleled run the check lands on the individual conductor, because that is what goes into the lug. Our bank works a two set feeder where each conductor derates to 240 amperes and each conductor's 75 degree column figure is 255 amperes. Each conductor is good for 240, and only then do the sets add, giving 480 amperes. The 510 in the option list comes from using the termination figure for both conductors and dropping the derating, and the parallel rules are where that item actually lives.

The exam cost is the ordinary one. Each portion passes at 70 percent, the portions are scored separately, and a retake runs $78 whether you lost one portion or both.

What to do before you sit

• Tab 110.14(C) and Table 310.16 together, because the section sends you to a column and the table is where the column lives. Publisher tabs only, since homemade ones are turned away at the door.
• Write two lines on the inside cover of your working notes: factors go on the insulation column, and the termination column is read clean. Every item in this topic is one of those two lines applied.
• Practice reading a stem for the two triggers. Circle the ampere rating and circle any sentence about what the terminals are marked for, and answer the column question before you touch a number.
• Run ten paired items where one stem has the derating binding and the other has the termination binding. Candidates who lose these have only ever practiced one of the two shapes.

The worked comparison, with the columns named and both figures computed side by side, sits in the question set. This page is the exam-facing half of the same subject, and the continuous load multiplier is the other rule that lands on the same conductor before either limit is applied.

Questions people ask

Which temperature column does the Texas exam expect?

The one 110.14(C)(1) sets for the equipment in front of you. Circuits rated 100 amperes or less, along with equipment marked for 14 AWG through 1 AWG conductors, default to the 60 degree column. Circuits rated over 100 amperes, along with equipment marked for conductors larger than 1 AWG, default to the 75 degree column. Each side carries two independent triggers, so the terminal marking can put you on one side while the ampere rating would have put you on the other. Where the stem describes ordinary equipment with no marking, the default governs.

Does a 90 degree insulation help if my lugs are 75 degrees?

It helps wherever there is derating to do. 110.14(C) permits a conductor with a higher temperature rating to serve as the starting point for ambient correction, for conductor count adjustment, or for both, so you begin from a larger table figure and the factors work on that larger figure. In a hot roof or a full raceway that is often a trade size. It buys nothing where no factor applies: three conductors at the table's own ambient on 75 degree lugs get the 75 degree figure whether the insulation is rated 75 or 90.

Can I apply the derating factors to the termination column?

No. The termination limit is read from the table with no correction and no adjustment applied to it, and the factors belong on the ampacity at the conductor's own temperature rating. One bank stem describes a candidate who takes the 75 degree figure of 115 amperes, applies a 0.82 correction and a 0.80 adjustment to it, and reports 75 amperes. The factors belong on the 90 degree value, and the 115 amperes is a ceiling the result is measured against at the end. Applying them to the lower column oversizes the conductor and reads as a safe error.

Does a 90 degree stamp on equipment open the 90 degree column?

The permission attaches to equipment listed and identified for use with conductors of that rating, so a temperature number cast near a terminal leaves the column where 110.14(C)(1) put it. The evidence sits in the listing and in the instructions that come with the equipment. Most ordinary breakers, panelboards and safety switches are 75 degree equipment at best. The route that does open a higher termination is 110.14(C)(2), covering pressure connectors bought and installed separately from the equipment, where the conductor may be used at an ampacity no greater than the connector's own listing allows.

Is the limit different for a feeder and a branch circuit?

The kind of circuit never enters into it. 110.14(C) asks what the equipment is marked for and whether the circuit is rated over 100 amperes, so identical conductors on identical equipment at the same rating land in the same column either way. A bank item puts exactly that question up, and the wrong options invent a feeder rule and a branch circuit rule. What does differ between the two is where the load comes from and which article carries the 125 percent for a continuous load, and both of those are settled before any column is chosen.

How does the termination check work on a parallel run?

On the individual conductor, because the individual conductor is what lands in the lug. A bank item gives a two set feeder where each conductor derates to 240 amperes and each conductor's 75 degree column figure is 255 amperes. The lower of the two governs each conductor at 240 amperes, and the sets then add to 480 amperes for the feeder. The 510 ampere option comes from using the termination figure for both conductors and dropping the derating that produced 240, and a 495 option averages the two limits, which no rule permits.