Written against the 2026 NEC and checked section by section, September 2026
Equipment Grounding Conductor Sizing Practice Questions
These questions size the wire type equipment grounding conductor the way the code does it, from the rating of the overcurrent device ahead of the circuit and not from the conductor beside it. Table 250.122 gives the starting number, and the subdivisions under 250.122 then cap it, scale it, or replace the input entirely for motors, parallel runs and feeder taps. Watch for the two ceilings and for the one upsizing rule that ambient correction and conductor count adjustment do not trigger.
Pick an answer and the explanation opens with the section it comes from. These are original questions written for this site, not questions from the exam. Have your own code book open: the Texas exam is open book, and looking the section up is the skill being tested.
Read the equipment grounding conductor sizing study page first if the topic is new to you.
1. Table 250.122 is entered with which quantity?
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C. The rating of the overcurrent protective device ahead of the equipment
The left column of the table is the rating or setting of the automatic overcurrent device in the circuit ahead of the equipment, so that rating is the only way in. Conductor size matters later, as a ceiling, and never as the entry point. Reading the table at the conductor size is the most common single error on this topic.
NEC 2026 Table 250.122, 250.122
2. Article 100 defines the equipment grounding conductor as a conductive path that does what?
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A. Forms part of an effective ground fault current path and ties non current carrying metal parts to the grounded conductor or the grounding electrode conductor
The definition is written around the fault path, so this conductor exists to give fault current a low impedance road back to the source. Reaching earth is the grounding electrode conductor's job and it has its own definition a few lines away. Unbalanced current belongs to the grounded conductor, which is a third thing again.
NEC 2026 Article 100
3. A 400 ampere device protects a feeder run in aluminum. Which aluminum conductor does Table 250.122 give for the equipment grounding conductor?
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D. 1 AWG
The 400 ampere row reads 3 AWG copper and 1 AWG aluminum, so an aluminum installation takes 1 AWG. Picking 3 AWG means reading the copper column out of habit. The aluminum entry is always larger than the copper entry in the same row, so an answer that matches the copper column on an aluminum question deserves a second look.
NEC 2026 Table 250.122
4. A motor branch circuit is protected at 60 amperes by an inverse time breaker, and the branch circuit conductors are 12 AWG copper. What size copper equipment grounding conductor is required?
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B. 12 AWG
The table reads 10 AWG at 60 amperes, but the first subdivision of the section says the grounding conductor is never required to be larger than the circuit conductors supplying the equipment. Those conductors are 12 AWG, so 12 AWG is the answer and the table value is the trap. Motor circuits throw this pattern often, because the short circuit device is allowed to sit well above the conductor ampacity.
NEC 2026 250.122, 250.122(A), Table 250.122
5. The ungrounded conductors of a feeder are increased for voltage drop so that their circular mil area is 1.5 times what the load required. The table calls for a 6 AWG copper grounding conductor of 26,240 circular mils. What is the minimum circular mil area of the grounding conductor after the increase?
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A. 39,360 circular mils
The rule scales the grounding conductor by the same proportion the ungrounded conductors were increased, and it says so in circular mils rather than in trade sizes. One and a half times 26,240 is 39,360, and you then pick the smallest conductor at or above that area. Doubling gives 52,480 and dividing gives 17,493, and neither matches the ratio the stem hands you.
NEC 2026 250.122
6. The ungrounded conductors of a circuit are increased one size because six current carrying conductors share the raceway. What happens to the wire type equipment grounding conductor?
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C. It stays at the size the table gives for the device rating
The upsizing rule names two increases that it deliberately does not apply to, and adjustment for the number of current carrying conductors is one of them. Ambient temperature correction is the other. Only an increase made for some other reason, voltage drop being the usual one, drags the grounding conductor up with it.
NEC 2026 250.122, 310.15(C)
7. The subsection that requires a proportional increase carries an exception. What does that exception permit?
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B. A qualified person may size the grounding conductor to provide an effective ground fault current path
The exception hands the sizing to a qualified person, provided the result still gives an effective ground fault current path under the performance rules. It is an engineering permission and not a way out of having a grounding conductor at all. An option that offers omission is offering something the section never allows.
NEC 2026 250.122, 250.4(A)(5)
8. Four branch circuits share one raceway, protected at 20, 20, 30 and 50 amperes. One equipment grounding conductor is installed for all four. How is it sized?
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D. From the 50 ampere device, the largest one protecting circuit conductors in that raceway
A single grounding conductor may serve several circuits in the same raceway, cable, trench or cable tray, and it is read from the table at the largest overcurrent device protecting any of those circuit conductors. That is 50 amperes here, so the table gives 10 AWG copper. Adding the ratings together is not in the section anywhere and produces a conductor far larger than it asks for.
NEC 2026 250.122, Table 250.122
9. Wire type equipment grounding conductors are sectioned among the multiconductor cables of one circuit. What has to be true?
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A. The combined circular mil area of the sections meets the table value
The 2026 edition added a short subdivision allowing the grounding conductor to be sectioned within multiconductor cables as long as the areas add up to what the table calls for. It is written in circular mils, so the check is arithmetic rather than a trade size comparison. Asking each section to carry the full value on its own would make the permission pointless.
NEC 2026 250.122
10. A copper equipment grounding conductor for a feeder comes out of Table 250.122 at 1/0. What is the largest overcurrent device rating that row covers?
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B. 800 amperes
The left column reads as a ceiling, a rating not exceeding the figure printed, so the row that produces 1/0 copper tops out at 800 amperes. Six hundred amperes sits in the row above at 1 AWG copper and 1000 amperes in the row below at 2/0. Reading the table backward like this is a good check that you know which direction the column runs.
NEC 2026 Table 250.122
Ten down. If you want these timed and scored by content area, the practice exam runs thirty questions free, and the full bank of 178 plus the calculation ladder is $79 once.
11. A 1200 ampere feeder is run in four parallel raceways with a wire type equipment grounding conductor in each. How is each one sized?
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D. The table value read at 1200 amperes, in every raceway
The parallel rules size each raceway's grounding conductor from the one overcurrent device ahead of the whole feeder, so all four get the full table value, which is 3/0 copper at 1200 amperes. Nothing in the section divides that rating by the number of raceways. The fractions on the sheet are for candidates reasoning from the phase conductors, which are the part that gets divided.
NEC 2026 250.122, 250.122(H), Table 250.122
12. On that same paralleled feeder, what caps the grounding conductor inside an individual raceway?
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C. The largest ungrounded conductor in that raceway
The parallel rules carry a ceiling of their own: the grounding conductor in each raceway does not have to be larger than the largest ungrounded conductor sharing that raceway with it. The comparison is against what lies in that one enclosure, not against the paralleled set added up. That is why the 2026 wording of the general ceiling also names the raceway or cable.
NEC 2026 250.122, 250.122(H)
13. Circuit conductors are connected in parallel inside one raceway. What does the section permit for the equipment grounding conductor?
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A. A single wire type conductor sized on the feeder or branch circuit device
Where the parallel sets share one raceway, one wire type grounding conductor read from the table at the device rating is enough. The subdivision splits on enclosure count before it looks at anything else, so the first question is how many raceways there are, not how many sets. Multiple raceways is the case that puts a conductor in each one.
NEC 2026 250.122, 250.122(H)
14. A motor branch circuit is protected by an instantaneous trip circuit breaker. What rating is used to read Table 250.122?
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B. The largest dual element time delay fuse the motor rules would permit for that motor
Instantaneous trip breakers and motor short circuit protectors carry no ampere rating that makes a sensible table entry, so the section substitutes the largest dual element time delay fuse the motor branch circuit rules would allow. You work that number first, then read the grounding table at it. Using the trip setting produces a conductor far larger than the section asks for.
NEC 2026 250.122(F), 430.52(C)(1)(a), Table 250.122
15. A flexible cord supplies equipment and its largest circuit conductor is 10 AWG. What is the floor on the equipment grounding conductor in that cord?
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D. 18 AWG copper
The cord subdivision sets a floor of 18 AWG copper where the largest circuit conductor in the cord is 10 AWG or smaller, and it reaches fixture wires as well. Once the circuit conductor goes above 10 AWG the cord is sized from the table like everything else. The three wrong sizes are all ordinary branch circuit sizes, which is exactly why they look reasonable here.
NEC 2026 250.122(G)
16. Equipment grounding conductors run with feeder tap conductors are read from what rating, and what stops the answer?
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C. From the device ahead of the feeder on the supply side of the tap, and not required to be larger than the tap conductors
The tap subdivision reads the table at the overcurrent device sitting ahead of the feeder, upstream of the tap point, which is usually a large number. Then it stops the answer at the tap conductors themselves, which is what keeps the result sane. Apply only one half of that and the answer comes out either far too large or too small.
NEC 2026 250.122(I), Table 250.122
17. A metal raceway is used as the equipment grounding conductor instead of a wire. What does the sizing section require of it?
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A. That it satisfy the performance rules for an effective ground fault current path
The 2026 edition added a short subdivision saying trays, raceways, cable armor and sheaths used as grounding conductors have to meet the performance requirements in 250.4. There is no table row for a raceway, so the test is the fault path rather than a size. Which raceways qualify in the first place is settled in 250.118.
NEC 2026 250.122, 250.4(A)(5), 250.118
18. How is the terminal for the equipment grounding conductor on a wiring device identified?
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D. A green hexagonal terminal screw that is not readily removable
The section gives three acceptable forms and the first is a green screw with a hexagonal head that cannot be taken off easily. A green hexagonal nut and a green pressure wire connector are the other two. White and brass belong to the grounded and ungrounded terminals, which is what makes them useful wrong answers.
NEC 2026 250.126
19. May an automatic cutout or switch be placed in the equipment grounding conductor of a premises wiring system?
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B. Only where opening it disconnects all sources of energy
The continuity section bars a switch or cutout in the grounding conductor unless opening it also drops every source feeding the equipment. The reason shows itself once you picture it: a grounding conductor opened while the circuit is live leaves energized equipment with no fault path. Ampere rating and occupancy have nothing to do with the rule.
NEC 2026 250.124
20. A feeder supplies branch circuits that require equipment grounding conductors. What does Article 215 ask of that feeder?
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C. That the feeder include or provide an equipment grounding conductor for the branch circuit ones to land on
The feeder article carries one short grounding sentence, and it says the feeder has to include or provide the grounding conductor that the branch circuit grounding conductors connect to. It names no wiring method, so a qualifying metal raceway can be the means. Ground fault protection of equipment is a separate rule with its own ampere and voltage triggers.
NEC 2026 215.6
21. Bare or covered aluminum equipment grounding conductors carry an installation restriction. Which of these is it?
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A. They are not installed in direct contact with concrete, masonry or the earth
The installation section keeps bare or covered aluminum out of corrosive conditions and out of direct contact with concrete, masonry or earth unless it is part of a cable wiring method. A second restriction sets distances for terminations near the earth and near the bottom of listed outdoor enclosures. Neither one turns on the circuit rating or on the kind of building.
NEC 2026 250.120
22. An equipment grounding conductor smaller than 6 AWG is not routed with the circuit conductors. What does the code ask for?
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B. Protection by an identified raceway or cable armor, unless it runs in hollow spaces of building framing and is not subject to damage
Small grounding conductors run on their own are easy to damage, so the section asks for an identified raceway or cable armor around them. The relief is for conductors inside the hollow spaces of framing members where damage is not a live concern. This is the equipment grounding rule, and it is easy to confuse with the similar looking 6 AWG hinge that governs the grounding electrode conductor.
NEC 2026 250.120
23. Which conductor does Table 250.122 not size?
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D. The conductor from the service to a driven ground rod
The conductor to the rod is the grounding electrode conductor, and it comes out of Table 250.66 read at the service conductor size. Everything else on the list runs with circuit conductors and lands on equipment, which is this table's territory. The quickest way to sort them in an item is to look at where the far end of the conductor stops.
NEC 2026 250.122, 250.66
24. What does Table 250.122 give as the copper equipment grounding conductor on a 15 ampere branch circuit wired in 14 AWG copper?
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C. 14 AWG
The first row of the table pairs a 15 ampere device with 14 AWG copper and 12 AWG aluminum. The circuit conductors here are also 14 AWG, so the ceiling that stops the grounding conductor at the circuit conductors changes nothing. The table prints nothing smaller than 14 AWG copper, so 16 AWG is never an answer taken from it.
NEC 2026 Table 250.122, 250.122(A)
25. Table 250.122 carries a note about going above the size it prints. When does that note apply?
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A. Where the performance rules for the fault current path call for more
The note under the table points back at the performance requirements for an effective ground fault current path and says the conductor is sized larger where meeting them takes more. Impedance on a long run is one reason that can happen, but the note names the performance rule rather than a distance. Length on its own is not a trigger printed anywhere in the section.
NEC 2026 Table 250.122, 250.4(A)(5)
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