Texas Electrician ExamTexas journeyman & master

Checked against primary sources 2026-08-24

The other grounding table, and the one people reach for by mistake

Sized from the overcurrent device ahead of it, not from the conductor beside it, and not from the service size. Then two separate rules cap the answer.

On this page
  1. Which conductor this is
  2. The input is the device rating
  3. The cap that turns an absurd answer into the right one
  4. When it has to be upsized, and when it does not
  5. Parallel runs, sorted by geometry first
  6. Working an item end to end
  7. Where the letters moved
  8. What this page cites

Which conductor this is

It runs with the circuit conductors and bonds metal back toward the source. It is the fault-current path, and it is the only conductor on a branch circuit whose job is to be there when something has already gone wrong.

It is not the grounding electrode conductor, which ends on an electrode and takes its size from a different input entirely.

The quickest way to tell them apart in an item is the far end. Electrode, or a point on the electrode system, means the other conductor. Equipment means this one.

The input is the device rating

Wire-type equipment grounding conductors of copper, aluminum or copper-clad aluminum are sized from Table 250.122, entered on the rating of the overcurrent protective device ahead of the circuit (NEC 250.122).

Not from the circuit conductor size. Not from the load. Not from the service. From the device.

That is deliberate. The conductor has to hold together long enough for that specific device to open, so the device rating is the quantity that matters.

Look the value up in your own code book. The table is short and it is worth an individual tab, because it sits several pages away from the grounding electrode table that people confuse it with.

The cap that turns an absurd answer into the right one

An equipment grounding conductor is not required to be larger than the circuit conductors in the raceway or cable supplying the equipment (NEC 250.122).

That subdivision, titled Not Larger Than Circuit Conductors, sits first in the 2026 edition at 250.122(A), ahead of everything else, and it is there because the table alone can produce nonsense. A small circuit protected by a large device would otherwise take a grounding conductor bigger than the conductors it is protecting.

The 2026 wording adds "in the raceway or cable", which matters on a parallel run. The comparison is against the conductors sharing the enclosure with it, not against the whole paralleled set.

An item that gives you a small conductor and a big device is testing this rule and nothing else. Read the answer choices for the one that equals the circuit conductor.

When it has to be upsized, and when it does not

Increase the ungrounded conductors for any reason other than as required in 310.15(B) or 310.15(C), and a wire-type equipment grounding conductor, if installed, is increased in proportion to the increase in circular mil area of the ungrounded conductors (NEC 250.122).

The two named sections are ambient temperature correction and adjustment for the number of current-carrying conductors. Upsize because a run is hot or crowded and the grounding conductor stays where the table put it. Upsize for voltage drop, or because somebody specified heavier wire, and it goes up with them.

The distinction has a physical reason behind it. Correction and adjustment are about the conductor getting rid of heat over the same distance. Voltage drop upsizing is about a run being long, and length is exactly what raises the impedance of the fault path.

This is a place where old study material is actively dangerous, because the previous wording turned on whether the conductor was larger than the minimum with sufficient ampacity, and it produced a different answer on a derating item.

Parallel runs, sorted by geometry first

The subdivision titled Conductors in Parallel, at 250.122(H) in the 2026 edition, splits before it does anything else, and the split is on where the conductors are, not how many there are.

One conductor or several is decided by the enclosure count. The size is decided by the one device ahead of the whole run in every case, and it is never a share of that rating.

Then the second cap lands. The grounding conductor in each raceway is not required to be larger than the largest ungrounded conductor in that raceway (NEC 250.122). So on a paralleled feeder the per-raceway answer is bounded twice over, once by the table read at the device rating and once by the phase conductor lying next to it.

The wrong answers on a parallel item are almost always fractions. Divide by the raceway count and you will find your number on the sheet.

Working an item end to end

Four steps, in this order, and the order is what keeps you out of the traps.

  1. Find the overcurrent protective device rating ahead of the circuit. Not the load, not the conductor.
  2. Read Table 250.122 at that rating.
  3. Check whether the ungrounded conductors were increased for something other than ambient correction or conductor-count adjustment. If they were, scale up in proportion to the circular mil increase.
  4. Apply the cap. The answer never has to exceed the circuit conductors in that raceway or cable.

Run it on three cases. An ordinary 20 ampere lighting circuit: the table gives the answer and neither the upsizing rule nor the cap ever bites. A long feeder whose phase conductors were moved up two sizes for voltage drop: step three applies and the grounding conductor moves with them, in proportion to circular mils rather than by two table rows. A circuit whose conductors are small relative to the device ahead of them: the table hands you a number and step four holds the answer at the circuit conductor.

Skip step three and you underanswer. Skip step four and you overanswer. Both wrong answers will be printed for you.

Where the letters moved

The 2026 edition promoted three rules that used to sit unlettered inside the first subdivision, which pushed every subdivision behind them down one letter. The section now runs from 250.122(A) through 250.122(I) where the previous edition stopped at (G).

The consequence for the exam is narrow but real. An item that quotes a subdivision letter is quoting the edition the exam is referenced to, and from September 1, 2026 in Texas that is the 2026 edition (16 TAC 73.100).

The safe habit is to find the subdivision by its title rather than by a letter you remember. Not Larger Than Circuit Conductors, Increased in Size, Conductors in Parallel, Feeder Taps. The titles have not moved.

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.