Texas Master Electrician Practice Test (PSI, 2026 NEC)

20 free Texas Master practice questions with answers

Pick your answer, then open it to see the explanation and the 2026 NEC section.

1. Branch Circuit Conductors

   The conductor ampacity does not match a standard overcurrent device rating. Which circuit may use the next higher standard rating for the overcurrent device?

   1. A multi-outlet branch circuit for portable cord-and-plug loads whose conductors have an ampacity of 38 amperes, protected at 40 amperes
   2. A feeder whose conductors have an ampacity of 900 amperes, protected at 1,000 amperes
   3. A feeder to a panelboard whose conductors have an ampacity of 90 amperes, protected by a 100-ampere device
   4. A feeder whose conductors have an ampacity of 90 amperes, protected at 125 amperes
   Show answer

   Answer: 3. A feeder to a panelboard whose conductors have an ampacity of 90 amperes, protected by a 100-ampere device

   The next higher standard rating may be used for conductors that are not part of a multi-outlet branch circuit supplying receptacles for cord-and-plug portable loads, when the ampacity does not match a standard rating and the next size up does not exceed 800 amperes. 100 amperes for 90-ampere conductors meets that, while the portable-load circuit, the 1,000-ampere device and the 125-ampere device do not.

   Reference: NEC 240.4(B) (NEC 2026)

2. Branch Circuit Conductors

   Under the exception for short raceways, an adjustment factor for more than three current-carrying conductors does not apply to conductors in a nipple of what maximum length?

   1. 12 in.
   2. 18 in.
   3. 24 in.
   4. 36 in.
   Show answer

   Answer: 3. 24 in.

   The adjustment factor does not apply to conductors in a raceway nipple that is not longer than 24 in. 12 in. and 18 in. are shorter than the limit, and 36 in. is longer.

   Reference: NEC 310.15(C)(1) (NEC 2026)

3. Motors and Generators

   For which purpose is the motor nameplate current used instead of the table full-load current?

   1. Sizing the separate motor overload protection
   2. Sizing the branch-circuit conductors
   3. Sizing the branch-circuit short-circuit and ground-fault protective device
   4. Sizing the ampere rating of the motor disconnecting means
   Show answer

   Answer: 1. Sizing the separate motor overload protection

   Conductors, short-circuit and ground-fault protection and ampere-rated disconnects are sized from the table full-load current, while a separate overload device is based on the nameplate current. The other three uses all rely on the table value.

   Reference: NEC 430.6(A) (NEC 2026)

4. Special Occupancies, Equipment, and Conditions

   Which Class II group includes flour, starch and grain dusts?

   1. Group E
   2. Group G
   3. Group F
   4. Group D
   Show answer

   Answer: 2. Group G

   Class II Group G covers combustible dusts such as flour, starch and grain that are not metal or carbonaceous dusts. Group E is combustible metal dust, Group F is carbonaceous dust such as coal, and Group D is a Class I gas group, not a dust group.

   Reference: NEC Article 500 (Class II groups) (NEC 2026)

5. Electrical Feeders

   A feeder is protected by an 800-ampere overcurrent device and is installed as two parallel sets in two separate conduits. For copper, the equipment grounding conductor table gives 400 A, 3 AWG; 500 A, 2 AWG; 600 A, 1 AWG; 800 A, 1/0 AWG; 1,000 A, 2/0 AWG; 1,200 A, 3/0 AWG. What size copper equipment grounding conductor goes in each conduit?

   1. 3 AWG
   2. 1 AWG
   3. 1/0 AWG
   4. 2/0 AWG
   Show answer

   Answer: 3. 1/0 AWG

   With parallel sets in separate raceways, each conduit gets an equipment grounding conductor sized from the 800 A overcurrent device, which is 1/0 AWG copper. 3 AWG sizes each conduit for half of the device rating, the 400 A row, which gives 3 AWG. 1 AWG uses the 600 A row, which gives 1 AWG. 2/0 AWG uses the 1,000 A row, which gives 2/0 AWG.

   Reference: NEC Article 250 (equipment grounding conductors for parallel feeders; 250.122(F) in the 2023 NEC) (NEC 2026)

6. Electrical Wiring Methods and Electrical Materials

   Single-conductor 3/0 AWG cables listed for cable tray use are installed in a ladder cable tray in an industrial plant. What is the maximum rung spacing permitted for that tray?

   1. 6 in
   2. 9 in
   3. 12 in
   4. 18 in
   Show answer

   Answer: 2. 9 in

   Single-conductor cables 1/0 through 4/0 AWG in a ladder cable tray need rungs spaced no more than 9 in apart so the cables are adequately supported. 6 in is permitted but is not the maximum. 12 in and 18 in leave these cable sizes with too little support.

   Reference: NEC Article 392 (single conductors in ladder cable tray) (NEC 2026)

7. Electrical Equipment and Devices

   In an existing building, a dead-front switchboard and a dead-front panelboard that face each other across an aisle are being replaced, and the aisle cannot be widened to the depth Condition 3 would need. Under what arrangement does the NEC permit Condition 2 working clearance between them?

   1. Written procedures keep equipment on both sides from being open at the same time, and only authorized qualified persons service it
   2. The new equipment is rated 1,200 amperes or less
   3. Arc-flash warning labels are applied to both pieces of equipment and the room door is kept locked at all times by the building owner
   4. The working space has an entrance at each end of the aisle
   Show answer

   Answer: 1. Written procedures keep equipment on both sides from being open at the same time, and only authorized qualified persons service it

   In existing buildings where equipment is being replaced, Condition 2 clearance is permitted between dead-front switchboards, switchgear, panelboards or motor control centers across an aisle when written procedures prohibit equipment on both sides from being open at the same time and authorized qualified persons service the installation. An ampere limit is not part of this permission. Warning labels, a locked door or a second entrance do not stop both sides from being opened together.

   Reference: NEC 110.26(A)(1) (NEC 2026)

8. Definitions, Theory, and Plans

   At a commercial site the utility sets a pad-mounted transformer, and its tariff places the service point at the transformer secondary terminals. The owner's contractor installs conductors underground from those terminals to a terminal box on the building wall. Under Article 100, what are these conductors?

   1. Underground service conductors, which are installed under the NEC
   2. A service lateral, which is utility property outside the scope of the NEC
   3. Feeder conductors, because they leave a transformer and supply the building
   4. Service-entrance conductors, because the owner installs them on the line side of the service disconnect
   Show answer

   Answer: 1. Underground service conductors, which are installed under the NEC

   A service lateral runs from the utility supply system to the service point, so once the service point is at the transformer secondary there is no service lateral on the customer side. The underground conductors from the service point to the first point of connection to the service-entrance conductors, in a terminal box, meter or other enclosure, are underground service conductors and are installed under the NEC. They are not feeders, which start at the service equipment or another source on the load side, and the service-entrance conductors begin only at the terminal box where these conductors end.

   Reference: NEC Article 100 (Service Conductors, Underground; Service Lateral) (NEC 2026)

9. Electrical Services, Service Equipment, and Separately Derived Systems

   A transformer separately derived system has its system bonding jumper installed at the transformer. The secondary feeder runs in EMT to the first disconnecting means, and the installer also bonds the neutral bar to the enclosure there. What does the second bond create?

   1. A required second bond that improves fault clearing at the first disconnecting means
   2. No problem, because the system bonding jumper may be installed at both locations whenever the feeder is in metal raceway
   3. A ground fault on the secondary, which trips the secondary main as soon as the transformer is energized
   4. A parallel path, so normal neutral current returns partly over the EMT and the other bonding paths
   Show answer

   Answer: 4. A parallel path, so normal neutral current returns partly over the EMT and the other bonding paths

   The system bonding jumper is installed at a single point, either at the source or at the first disconnecting means, so neutral current has only one path back to the transformer. Bonding the neutral at both places puts the EMT, the supply-side bonding jumper and other metal paths in parallel with the neutral, so normal load current flows on them as objectionable current. The second bond is not a ground fault and adds no fault-clearing benefit, and the narrow allowance for bonding at both locations applies only where no parallel path is created.

   Reference: NEC 250.30(A)(1) (NEC 2026)

10. Electrical Services, Service Equipment, and Separately Derived Systems

    At a new distribution center, the 2,000-ampere, 480Y/277-volt service switchboard includes equipment ground-fault protection, and it is about to be placed in service for the first time. What does the NEC require for that protection system?

    1. No field test, because the equipment was tested at the factory and is listed with its ground-fault sensors installed
    2. Performance testing when first installed, per the manufacturer's instructions, with a written record for the AHJ
    3. An annual test by the serving utility, with the result recorded on the meter tag at the service equipment
    4. A test only if the authority having jurisdiction asks for one after the system has caused a nuisance trip
    Show answer

    Answer: 2. Performance testing when first installed, per the manufacturer's instructions, with a written record for the AHJ

    Ground-fault protection of equipment at the service must be performance tested when it is first installed on site. The test follows the instructions provided with the equipment, and a written record of it is made available to the authority having jurisdiction. Factory testing does not replace the field test, which checks the neutral and sensor connections made during installation.

    Reference: NEC 230.95 (NEC 2026)

11. Electrical Feeders

    An existing detached shop is supplied by a 3-wire feeder (two ungrounded conductors and a neutral) with no equipment grounding conductor. It was installed under an earlier code that allowed the neutral to be bonded to the grounding electrode system at the shop. Under what conditions may this arrangement stay in service?

    1. Only if the shop's ground rod has been measured at 25 ohms or less and a second rod is added if it has not, with no other condition on the feeder or the buildings
    2. Only if the feeder is shorter than 100 ft and protected at 60 amperes or less, since any longer or larger feeder must be rewired with an equipment grounding conductor
    3. No equipment grounding conductor with the feeder, no continuous metal paths bonded between buildings, and no upstream ground-fault protection of equipment
    4. It may never remain in service; every existing feeder of this kind must be rewired with an equipment grounding conductor at the next inspection of the building
    Show answer

    Answer: 3. No equipment grounding conductor with the feeder, no continuous metal paths bonded between buildings, and no upstream ground-fault protection of equipment

    For installations made under earlier editions that permitted it, the grounded conductor run with the feeder may continue to serve as the ground-fault return path at the detached building if three conditions continue to be met: no equipment grounding conductor is run with the supply, no continuous metallic paths are bonded to the grounding system in each building, and ground-fault protection of equipment is not installed on the supply side of the feeder. If a condition changes, such as a metal water line run between the buildings, the neutral must be isolated and an equipment grounding conductor installed. Electrode resistance, feeder length and rating are not part of these conditions.

    Reference: NEC 250.32(B)(1) (exception for existing feeders without an equipment grounding conductor) (NEC 2026)

12. Electrical Equipment and Devices

    In a factory electrical room, a 480Y/277-volt panelboard is mounted directly above an auxiliary gutter that serves it. The front of the gutter projects 5 in. beyond the front of the panelboard into the required working space. How does the NEC treat this?

    1. Permitted; associated equipment above or below may extend up to 6 in. beyond the equipment front
    2. Not permitted; nothing may project into the working space below 6 1/2 ft
    3. Not permitted unless the projection is 2 in. or less
    4. Permitted for any projection, because an auxiliary gutter is not equipment likely to need servicing while energized
    Show answer

    Answer: 1. Permitted; associated equipment above or below may extend up to 6 in. beyond the equipment front

    Within the height of the working space, other equipment that is associated with the electrical installation and located above or below the electrical equipment may extend not more than 6 in. beyond the front of that equipment, so a 5-in. projection is permitted. The working space does not have to be free of every associated enclosure, and there is no 2-in. limit. The permission is not unlimited either: a gutter projecting more than 6 in. would intrude into the required working space.

    Reference: NEC 110.26(A)(3) (associated equipment above or below the equipment) (NEC 2026)

13. Motors and Generators

    A packaged make-up air unit uses a permanent-split capacitor blower motor that is marked with its motor type, and the unit nameplate lists that motor's full-load current. What current is used to size the conductors, controller, disconnect and protection for the blower motor?

    1. The NEC table full-load current for the motor's horsepower
    2. The table current for the next larger standard horsepower
    3. The locked-rotor current marked on the motor itself
    4. The full-load current marked on the equipment nameplate
    Show answer

    Answer: 4. The full-load current marked on the equipment nameplate

    Where equipment uses a shaded-pole or permanent-split capacitor fan or blower motor that is marked with the motor type, the full-load current marked on the equipment nameplate is used instead of the horsepower rating to size the disconnecting means, branch-circuit conductors, controller, short-circuit and ground-fault protection and overload protection. That is an exception to the general use of table currents, which do not fit these motors well. Locked-rotor current is the basis only for torque motors.

    Reference: NEC 430.6(A)(1) (shaded-pole and permanent-split capacitor fan or blower motors) (NEC 2026)

14. Electrical Control Devices and Disconnecting Means

    A 150-hp induced-draft fan motor in a power plant is located where a disconnect within sight of the motor would introduce additional hazards to persons. The controller disconnecting means is in a motor control center out of sight of the motor. When may the separate disconnect at the motor be omitted?

    1. When the controller disconnecting means is individually lockable in the open position
    2. When the motor control center is within 100 ft of the motor
    3. When a stop push button is installed next to the motor
    4. Never; a separate disconnect within sight of the motor is always required, whatever the hazard
    Show answer

    Answer: 1. When the controller disconnecting means is individually lockable in the open position

    A disconnect for the motor is not required where locating one in sight would be impracticable or introduce additional hazards, or in industrial installations with written safety procedures where only qualified persons service the equipment, provided the controller disconnecting means is individually capable of being locked in the open position. The stem gives the hazard condition, so the lockable controller disconnect completes the permission. Distance and a stop button do not isolate the motor, and the in-sight rule is not absolute.

    Reference: NEC 430.102(B) (motor disconnect not required when the controller disconnect is lockable) (NEC 2026)

15. Renewable Energy Technologies

    A rooftop PV system on a two-story retail building is equipped with rapid shutdown. Which of these may serve as the rapid shutdown initiation device?

    1. A switch inside the inverter enclosure that can be reached only with a tool
    2. Removal of the utility revenue meter from its socket
    3. A push button that does not show whether it is in the on or off position
    4. The building's service disconnecting means
    Show answer

    Answer: 4. The building's service disconnecting means

    The rapid shutdown initiation device may be the service disconnecting means, the PV system disconnecting means, or a readily accessible switch that plainly indicates whether it is in the off or on position, and its off position shows that rapid shutdown has been initiated. A switch reached only with a tool is not readily accessible. Pulling the meter is not an initiation method, and a device that does not show its position fails the indication requirement.

    Reference: NEC 690.12 (rapid shutdown initiation device) (NEC 2026)

16. Electrical Services, Service Equipment, and Separately Derived Systems

    An office building of 36,000 square feet has 150 general-use receptacle outlets, each counted at 180 VA. For the service calculation the receptacle load is the larger of (1) the outlet load after the receptacle demand factors (first 10,000 VA at 100 percent, the remainder at 50 percent) or (2) 1 VA per square foot of floor area (given). What receptacle load goes into the service calculation?

    1. 18,500 VA
    2. 23,000 VA
    3. 27,000 VA
    4. 36,000 VA
    Show answer

    Answer: 4. 36,000 VA

    The outlets give 150 x 180 = 27,000 VA, which after demand is 10,000 + 17,000 x 0.50 = 18,500 VA; the floor-area value is 36,000 x 1 = 36,000 VA, the larger, so 36,000 VA is used with no further demand factor. 18,500 VA uses the outlet load after demand and skips the floor-area comparison. 23,000 VA applies the receptacle demand factors to the 1 VA per square foot value. 27,000 VA uses the outlet count with no demand and no floor-area comparison.

    Reference: NEC 120.14(I) and Table 120.47; Article 120 (office building receptacle load: the larger of the outlet count or 1 VA per sq ft, given) (NEC 2026)

17. Electrical Services, Service Equipment, and Separately Derived Systems

    A service has three service disconnects in three separate enclosures, each with its own main bonding jumper. The copper service conductors are one set of 4/0 AWG to enclosure 1, one set of 600 kcmil to enclosure 2 and one set of 350 kcmil to enclosure 3. Each main bonding jumper is sized from the largest ungrounded conductor supplying its own enclosure (given). Copper sizing rows (given): over 3/0 AWG through 350 kcmil, 2 AWG; over 350 through 600 kcmil, 1/0 AWG; over 600 through 1,100 kcmil, 2/0 AWG; over 1,100 kcmil, 12.5 percent of the conductor area. What is the minimum copper main bonding jumper in enclosure 2?

    1. 2 AWG
    2. 1/0 AWG
    3. 2/0 AWG
    4. 3/0 AWG
    Show answer

    Answer: 2. 1/0 AWG

    Enclosure 2 is supplied by 600 kcmil, which is in the over-350-through-600 row, so its main bonding jumper is 1/0 AWG; the other enclosures are sized from their own conductors and are not added in. 2 AWG sizes from the 350 kcmil set of enclosure 3. 2/0 AWG puts 600 kcmil in the over-600 row, although 600 is the top of the row below. 3/0 AWG adds the three enclosures together and applies 12.5 percent.

    Reference: NEC 250.28(D) (main bonding jumper size; each enclosure sized from the conductors supplying it, rule and table rows given) (NEC 2026)

18. Branch Circuit Calculations and Conductors

    A 100-A circuit breaker supplies a single 100-A noncontinuous load. Neither the breaker nor the equipment terminals are marked with a temperature rating. The THHN copper conductors run in a raceway with three current-carrying conductors through a space where the correction factor for the 90 degree C column is 0.91. Copper ampacities at 60 / 75 / 90 degrees C (given): 3 AWG 85 / 100 / 115 A; 2 AWG 95 / 115 / 130 A; 1 AWG 110 / 130 / 145 A; 1/0 AWG 125 / 150 / 170 A. What is the smallest conductor permitted?

    1. 3 AWG
    2. 2 AWG
    3. 1 AWG
    4. 1/0 AWG
    Show answer

    Answer: 3. 1 AWG

    Terminals of a circuit rated 100 A or less that are not marked must be treated as 60 degree C, so the conductor needs at least 100 A in the 60 degree C column, which 1 AWG (110 A) meets; its corrected 90 degree C ampacity, 145 x 0.91 = 132.0 A, also covers the load. 3 AWG checks only the corrected 90 degree C ampacity. 2 AWG uses the 75 degree C column although the terminals are not marked. 1/0 AWG applies 125 percent to a noncontinuous load.

    Reference: NEC 110.14(C)(1)(a), 310.15(B) and 310.16 (NEC 2026)

19. Motors and Generators

    A 100-horsepower, 460-volt, three-phase motor with a table full-load current of 124 A is started by a wye-start, delta-run controller, so six conductors run from the controller to the motor. The conductors between the controller and the motor are based on 58 percent of the motor full-load current, and like all single-motor conductors they get the 125 percent factor (given). What minimum ampacity do the conductors between the controller and the motor need?

    1. 41.3 A
    2. 51.7 A
    3. 71.9 A
    4. 89.9 A
    Show answer

    Answer: 4. 89.9 A

    Each winding conductor carries the phase current of the delta, so 124 x 0.58 = 71.92 A, and with the 125 percent factor 71.92 x 1.25 = 89.9 A. 41.3 A uses the one-third starting-current ratio of a wye start and no 125 percent. 51.7 A uses the one-third starting-current ratio of a wye start. 71.9 A takes 58 percent but leaves out the 125 percent.

    Reference: NEC 430.22; Article 430 (wye-start, delta-run motor conductors between controller and motor; percentage given) (NEC 2026)

20. Motors and Generators

    A 75-horsepower, 460-volt, part-winding-start motor has a table full-load current of 96 A. An inverse-time circuit breaker for this motor may be rated up to 250 percent of the full-load current. With a separate short-circuit and ground-fault device for each half of the winding, each device may be rated not more than one-half of the value permitted for the motor (given). What is the largest rating permitted for each half-winding breaker, before any next-standard-size allowance?

    1. 84.0 A
    2. 120.0 A
    3. 168.0 A
    4. 240.0 A
    Show answer

    Answer: 2. 120.0 A

    For the whole motor the limit is 96 x 2.50 = 240.0 A; each half-winding device may be one-half of that, 120.0 A. 84.0 A uses the 175 percent time-delay fuse value instead of the breaker value. 168.0 A uses the 175 percent fuse value and does not halve it. 240.0 A uses the whole-motor value without halving it.

    Reference: NEC Table 430.52(C)(1); Article 430 (part-winding motors: each half-winding device not more than one-half of the motor value, rule given) (NEC 2026)