Texas Electrician ExamTexas journeyman & master

Checked against primary sources 2026-08-24

You do not choose an electrode. You use what the building already has.

The rule is not pick one. It is bond together everything present at the building, then add if what is present is not enough. Three sections carry the whole topic.

On this page
  1. The sentence the article turns on
  2. What qualifies, and the condition attached to each one
  3. What encased actually asks for
  4. How 250.53 puts them in the ground
  5. The twenty-five ohm sentence, read the way it is written
  6. The water pipe is the one with no way out
  7. What does not count
  8. Reading an item on this topic
  9. What this page cites

The sentence the article turns on

Every grounding electrode present at a building has to be bonded together into one system The rule is not pick one. If a metal underground water pipe, a concrete encased electrode, a ground ring, a rod or pipe, or metal building frame is present at the structure, it is part of the system and must be bonded in. A rod is only permitted as a standalone electrode when none of the others exist. The grounding electrode conductor runs from the service to the system, and bonding jumpers tie the electrodes to each other. service GEC grade metal water pipe in contact 10 ft or more concrete encased electrode rod or pipe building steel all of them bonded together, not a menu to choose from a rod stands alone only when none of the others exist at the building
Present means required. The rod is what you use when nothing else is there, not a default. Drawn against NEC 250.50, 250.52(A) and 250.53. Sizing is Table 250.66, in your book.

Every grounding electrode present at a building or structure served gets bonded together with the others to form one grounding electrode system (NEC 250.50).

Present is the word doing the work. A house with a metal underground water pipe, reinforcing steel in the footing and a driven rod out back has all three in its system. Not the best one. All of them, tied to each other.

Where none of the qualifying electrodes is present, one or more of them gets installed (NEC 250.50). That is the only situation in which anybody picks an electrode, and it is why a rod is what you drive when the building offers nothing, rather than a default.

The list in 250.52 is not a ranking of quality. What 250.50 does is split it into two ranges: one set counts as part of the system whenever it happens to be there, and a shorter set is what you install when none of the first set exists. The letters bounding those two ranges have moved from one edition of the code to the next, so read the ranges in your own copy rather than from a number you remember.

One release is written into the section. A concrete-encased electrode in an existing building does not have to be brought into the system where the reinforcing steel cannot be reached without disturbing the concrete (NEC 250.50). New work gets no such relief, which is the half of the exception that items are built on.

What qualifies, and the condition attached to each one

Each entry in 250.52(A) is a description with a condition inside it, and the condition is the whole entry. A metal water pipe is not an electrode. A metal water pipe in contact with earth for a stated distance is.

Read those conditions as tests you apply to the building in front of you. Ten feet of pipe. Twenty feet of steel. Eight feet of rod. Two square feet of plate. An item that hands you a nine foot run of metal water pipe is not asking about grounding at all, it is asking whether you read to the end of the sentence.

What encased actually asks for

The concrete-encased electrode carries more conditions than any of the others, and the trade name Ufer hides most of them.

Two inches of concrete around the steel, and the concrete has to be in a footing or foundation that is itself in direct contact with the earth (NEC 250.52(A)(3)). The steel can run horizontally near the bottom of the footing or vertically inside a foundation or structural member that meets the same test.

That second condition is where real buildings fail it. A slab poured over a vapor barrier, or a footing separated from soil by rigid foam, has concrete and has steel and has no path to earth. For the 2026 edition NFPA restored and revised the informational note under this subdivision specifically to say what direct contact with the earth means, naming insulation and vapor barriers among the things that get in the way. A note explains rather than requires, but it tells you how the panel reads the sentence above it.

Twenty feet is a length, not a piece. One continuous twenty foot bar qualifies, and so does a run made up of shorter bars tied together with the usual steel tie wire, welded, or joined by other effective means (NEC 250.52(A)(3)).

Then the exception that decides items in both directions: where more than one qualifying concrete-encased electrode is present at a building, only one of them has to be bonded into the grounding electrode system (NEC 250.52(A)(3)). So a building on twelve footings is not a building with twelve grounding electrode connections. It is a building with one, and eleven the code declines to ask for.

How 250.53 puts them in the ground

250.52 says what a thing has to be. 250.53 says what you have to do with it, and the two get confused because both contain distances.

The rod and pipe rules are the ones that moved this cycle. NFPA restructured that subdivision for the 2026 edition so that the vertical eight foot installation is stated first and the rock-bottom relief follows it as two exceptions rather than as running text. The requirements are the same requirements. What changed is that a candidate reading down the page now meets the general case before the escape from it, which is the order the exam asks the question in.

The twenty-five ohm sentence, read the way it is written

The most misquoted line in Article 250 is the one people summarize as a grounding electrode system having to measure 25 ohms or less. No such requirement exists anywhere in the article.

What the section says is that a single rod, pipe or plate electrode gets supplemented by an additional electrode, and then an exception says the supplemental electrode is not required where that single electrode has a resistance to earth of 25 ohms or less (NEC 250.53(A)(2)).

Direction is everything here. The requirement is the second electrode. The measurement is the way out of the requirement, and an exception only helps somebody who can show its condition is met. That is why an installer who drives two rods and never owns a meter is compliant, and why an installer who drives one rod is relying on a number nobody wrote down.

What the sentence does not reach

It is written about a single rod, pipe or plate electrode. It is not written about a concrete-encased electrode, a ground ring, a metal underground water pipe, or a pair of rods already bonded to each other.

Work it against four buildings and it stops being slippery.

  1. A footing electrode and nothing else. There is no rod, pipe or plate in the system, so there is nothing to supplement and 25 ohms never enters the analysis. An answer choice offering a resistance test is there for people who learned the rule as a system requirement.
  2. Two rods, 6 feet apart, bonded together. The supplement is satisfied by what was installed. No measurement is called for, and none of the answer choices about ohms applies.
  3. One rod, measured, reading above 25 ohms. Add the second electrode. The section does not then ask you to measure the pair, because once the supplement is installed the exception is no longer the thing you are relying on.
  4. A metal water pipe supplemented by one driven rod. The rod is still a single rod, pipe or plate electrode, and the subdivision is written about what the electrode is rather than about the job it was brought in to do. Read it that way and the second rod is the safe answer.

Driving two and moving on is not a shortcut around the code. It is the code, taken at the reading that avoids having to prove anything.

The water pipe is the one with no way out

A metal underground water pipe gets supplemented by an additional electrode of another type, and no resistance measurement excuses it. That rule sits under the subdivision titled Metal Underground Water Pipe (NEC 250.53(D)), and finding it by that title is safer than finding it by the letter. It is the difference between the water pipe and the rod, and it is worth holding on its own.

The supplement can be any of the other qualifying types. It cannot be a second metal water pipe, because the subdivision sends you past that entry in the list on its way to the others.

The reason is not electrical, it is custodial. The water pipe is the only electrode in the set that somebody else owns and somebody else maintains. A plumber replaces twenty feet of galvanized with plastic on a Tuesday and the electrode quietly stops existing, with nothing on the panel to say so. A system leaning on a pipe you do not control needs a second leg that you do, and that is why this subdivision has no measurement in it.

What does not count

Three things are named as not permitted for use as grounding electrodes: metal underground gas piping systems, aluminum, and the structures and reinforcing steel of a swimming pool (NEC 250.52(B)).

Gas piping is the one that catches people, because the intuition runs the other way and because a gas line does get bonded. Bonding a metal gas line that is likely to become energized is a separate obligation written elsewhere in Article 250, and satisfying it does not turn the line into an electrode. An answer choice offering underground gas piping as part of a grounding electrode system is wrong however the rest of the scenario reads.

Aluminum is excluded outright, which sits alongside the separate aluminum restrictions on the grounding electrode conductor and gets remembered as one rule when it is two. And anything not on the list and not listed as an electrode simply is not one, because there is no general permission for a made electrode that seems as good.

Reading an item on this topic

These items are short and they are decided by one word in the stem. The four tells are worth knowing cold.

None of it is memorization work. The three sections sit within a couple of pages of each other, so tab 250.50 and read forward.

What this page cites

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