Where the neutral to ground bond belongs, and how a Texas exam checks that you know it

One bond, at the service

The connection between the grounded conductor and the equipment grounding system is made once, inside the enclosure that holds the service disconnecting means, by an unspliced main bonding jumper (NEC 250.24(C)). Past that enclosure the grounded conductor stays clear of equipment grounding conductors, of metal parts and of any second connection to ground (NEC 250.24(B)). Older references cite the load-side rule as 250.24(A)(5), and in the 2026 edition it sits at (B).

NEC 250.142(B) states the same prohibition for the whole system, and it names two ways out by number, 250.30(A)(1) and 250.32(B)(1) Exception No. 1. Everything else is closed, which is why a subpanel gets an isolated neutral bar sitting on insulators, a separate grounding bar bonded to the can, and four wires in the feeder that reaches it.

How the exam asks it

Our bank of 500 original Texas practice items puts 66 of them in the grounding and bonding area, and this one rule accounts for more of those 66 than any other section in Article 250. The PSI content outline prints no line called grounding at all, so these items arrive inside other areas. Services, service equipment and separately derived systems carries 6 of the 56 scored knowledge items. Electrical feeders carries 3. The three heaviest areas on that portion carry 10 each, and grounding questions are folded into all of them.

Three shapes cover nearly every item we have written on the bond.

• The identification item. A subpanel is fed from the main panel in the same building, and you say what happens to the two bars. Roughly a third of our grounding items open this way.
• The symptom item. A clamp meter on the metal water line between a house and a detached shop reads 6 amperes with everything working normally and nothing faulted, or a ground-fault circuit interrupter in a subpanel trips the moment its load comes on. You are asked for the cause, and the cause is the same in both.
• The source item. A step-down unit or a second building sits between the service and the panel being asked about, and the answer moves with it.

That second shape is the one worth practicing, because it arrives worded as a field complaint. A candidate who has only memorized the rule as a sentence about bars reads a question about a water line and goes hunting through the piping requirements while the clock runs down.

Every wrong answer invents a condition

Read the distractors across our grounding items and one pattern covers most of them. The section states the rule flat, with no qualifying condition, so each wrong answer has to supply one from somewhere.

The drill is to notice the shape while you read. An answer that hangs the bond on an ampere rating or on a wiring method has added something the section never said, and you can strike it before you open the book, which buys you the minute you need for the items that genuinely require a page turn.

One question answers five items

Work the five cases once and they stay worked.

1. Utility service. Main bonding jumper, unspliced, in the service disconnect enclosure (NEC 250.24(C)). The grounded conductor is also run to each service disconnecting means and landed on its terminal even where the load has no use for a neutral (NEC 250.24(D)), because at that point it's the fault-current path back to the source on the utility side.
2. Another panel in the same building. The neutral bar floats and the grounding bar bonds to the can (NEC 250.142(B)).
3. Downstream of a step-down unit. A new source with a single-point bond of its own, which is a subject in its own right and is worked through on separately derived systems.
4. A second building on the same property. An equipment grounding conductor runs with the supply conductors and lands on the enclosure holding the building disconnecting means, the structure gets a grounding electrode system of its own, and the grounded conductors there stay clear of the equipment grounding conductors and the electrodes (NEC 250.32(B)(1)).
5. A range, an oven or a dryer. Frames connect to the equipment grounding conductor (NEC 250.140). The old three-wire allowance survives as an exception reaching existing branch-circuit installations where no equipment grounding conductor is present in the outlet or junction box, and four conditions attach to it.

Case four is the one people get backwards in both directions, because the practice of bonding at an outbuilding is still visible in the field and survives only under an exception for installations made before the current rule. The conductor doing the work there is the one covered on the equipment grounding conductor, sized from 250.122, while the electrode conductor at that same structure is sized from 250.66 with the ceiling that matches the electrode at its far end.

Where it sits in the book

Five section numbers hold the whole subject, and learning the numbers is worth as much as learning the rule on an open-book paper where your score depends on how fast your hand finds the page.

• 250.24(B) the load-side restriction, carried at 250.24(A)(5) in editions before 2026.
• 250.24(C) the main bonding jumper, unspliced, with an exception for multiple disconnects in an assembly listed for use as service equipment and another for impedance grounded systems.
• 250.24(D) the grounded conductor brought to each service disconnecting means and landed on its terminal or bus.
• 250.28 material, construction, attachment and size for the main bonding jumper and the system bonding jumper.
• 250.142 where a grounded circuit conductor may be used to ground equipment, which is the general form of the prohibition and the section an item quotes when it asks the question in the abstract.

Texas adopts the 2026 National Electrical Code on 1 September 2026 under 16 TAC 73.100, and the examinations reference that edition from the same day. Article 250 kept its number and several sections inside the book moved this cycle, so a tab set built for a 2023 copy sends your hand to the wrong page while the clock runs. Our page on which code edition applies works through what that means for a book you already own and for the four hours you owe at renewal.

What it costs on the job

A second bond is quiet. Nothing trips, nothing smells and nothing fails an energized test, so the arrangement survives until somebody either inspects it or puts a meter on it.

The commonest finding is a dwelling with the meter and main disconnect outside and a panelboard inside fed from that disconnect. The indoor panel sits on the load side of the service disconnecting means, so it's wired like any other subpanel, and the bonding screw left in its neutral bar is the thing an inspector writes up. The remedy is a green screw, a bar kit and a return trip, and the return trip is the expensive part of that list.

The measurable version is 6 amperes of load current on a metal water line with nothing faulted, which is the current 250.6 calls objectionable. Return current takes every path back to its source in proportion to impedance, so a bond at a downstream panel hands building metal a share of the neutral current for as long as the arrangement stands. Cutting the water line bond looks like a cure and removes a connection the code requires, while separating the bars at the downstream panel is what actually settles it.

The third version arrives as a ground-fault circuit interrupter that trips as soon as its load runs, because the device compares the current going out with the current coming back through it and a neutral to ground connection past it gives part of the return a way around the sensor. Texas puts the compliance duty on people by name: 16 TAC 73.53 requires electrical work to be performed in compliance with applicable codes and ordinances, and 16 TAC 73.51(g) places supervision and regulatory compliance on the contractor and the master electrician together. Cities amend on top of the state adoption, which is the subject of what a city can still require of you.

What to do before test day

Four things, and none of them takes an evening.

1. Read 250.24 in your own copy, in place, and mark (B), (C) and (D) separately. They answer different questions and items are built on the difference between them.
2. Draw the five source cases from this page on one sheet and write the bond location on each. Keep the sheet at home, because the exam is open book on the code alone and no notes of yours go in with you.
3. Answer thirty items under a clock, and read the explanation on the ones you got right as well, since a right answer for the wrong reason fails the next item in the family. The free timed practice set shows the section behind each one.
4. Check the book you plan to carry. A soft-bound copy is admitted, publisher tabs are admitted, and writing or highlighting during the session is refused, so everything you want in that book goes in beforehand.

If what you want is the arithmetic worked line by line, with the sizing traced and the figures set out, that lives in the question set. This page is the Texas candidate's view of the same rule: how it gets asked, which distractor takes people, and what a second bond costs once an inspector arrives on site.

Questions people ask

Does the neutral bond to the enclosure at a subpanel?

The two bars stay separate there. At a panel fed from another panel in the same building, the grounded conductors land on a neutral bar isolated from the enclosure and the equipment grounding conductors land on a separate bar bonded to the can, with the bonding screw or strap removed. NEC 250.24(B) bars reconnecting the grounded conductor to ground on the load side of the service disconnecting means, and NEC 250.142(B) bars using it to ground equipment there. No ampere rating and no wiring method releases that, which is exactly what the distractors on this item offer you.

Where does the main bonding jumper go when the disconnect is outside?

In the outside enclosure, because that enclosure holds the service disconnecting means and NEC 250.24(C) puts the jumper there. Once the disconnect sits outside, the panelboard indoors is fed by a feeder and is wired like any other subpanel: an isolated neutral bar, a bonded equipment grounding bar, and a four-wire feeder between the two enclosures. Leaving the factory bonding screw in the indoor panel is the most common finding on this arrangement, and it produces exactly the parallel neutral path the rule exists to prevent.

Does a detached shop get its own neutral to ground bond?

It gets a grounding electrode system of its own and a single bond back at the service. NEC 250.32(B)(1) runs an equipment grounding conductor with the supply conductors, connects it to the enclosure holding the building disconnecting means and to the grounding electrode conductor, and sizes it from 250.122. The same subsection keeps the grounded conductors at that structure clear of the equipment grounding conductors and the electrodes. Both the feeder grounding conductor and the electrode conductor land on the grounding bar, and the neutral bar at the shop stays isolated on its insulators.

Why does a GFCI breaker in a subpanel trip as soon as the load runs?

Because part of the return current is bypassing the device. A ground-fault circuit interrupter compares the current leaving on the ungrounded conductor with the current coming back through it on the grounded conductor. A neutral to ground connection downstream of the device hands some of that return a second way home, through the equipment grounding conductors and the metal bonded to them, and the device reads the difference as leakage. The tripping is a symptom of the load-side connection NEC 250.24(B) forbids, and isolating the neutral bar at the subpanel clears it.

Is a three-wire feeder to a subpanel still permitted in new work?

New work carries an equipment grounding conductor with the feeder. NEC 250.24(B) bars reconnecting the grounded conductor to ground past the service disconnect and NEC 250.142(B) bars using it to ground equipment there. The allowance people remember was written for a separate structure and only for installations made under earlier editions, and it never reached a panel inside the same building. Left in place, the arrangement puts neutral current on the equipment grounding path of that subpanel and on every piece of metal bonded to it, which is the condition 250.6 is written against.

How many exam questions cover the neutral to ground bond?

Our bank of 500 original Texas practice items puts 66 in the grounding and bonding area, and the neutral to ground bond accounts for more of those than any other section in Article 250. The PSI content outline prints no area called grounding, so these items are distributed across the paper: services, service equipment and separately derived systems takes 6 of the 56 scored knowledge items, electrical feeders takes 3, and the three heaviest areas take 10 each with grounding folded in. Treat it as a section you will meet several times in one sitting.