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NEC 2023 Code Questions Practice Test 12

Free NEC 2023 practice test with 30 questions on box fill, pull boxes, panelboards, and grounding rules. Plain-English questions with full explanations.

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This NEC 2023 Code Questions Practice Test 12 has 30 questions with detailed answers and NEC references. Take the full test, review every wrong answer, and look up the NEC article it references before moving on.

Tip: Mixed-format test — questions jump between topics just like the real exam. Don't spend more than 90 seconds on any one question.

Topics covered: All NEC chapters — branch circuits, grounding, conductors, wiring methods, motors, and more.
Passing score: Aim for 80%+ consistently before scheduling your exam.
Questions: 30 multiple-choice, one correct answer each

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NEC 2023 Code Questions Practice Test 12 — Question List

Question 1: A switch or receptacle on one strap counts as how many conductors in box fill?

Zero
One
Two
Three

NEC Reference: NEC 314.16(B)(4)

Question 2: One or more internal cable clamps in a box add how many conductors to the fill calculation?

One
One per clamp
Zero
Four

NEC Reference: NEC 314.16(B)(3)

Question 3: Each 10 AWG conductor in a box fill calculation needs a volume allowance of:

2.0 in3
2.25 in3
2.5 in3
3.0 in3

NEC Reference: NEC Table 314.16(B)

Question 4: In a wood wall, an outlet box can be set back from the finished surface by no more than:

1/4 inch
1 inch
2 inches
1/2 inch

NEC Reference: NEC 314.20

Question 5: For a straight pull, a pull box must be at least how many times the trade size of the largest raceway?

4 times
6 times
8 times
10 times

NEC Reference: NEC 314.28(A)(1)

Question 6: For an angle pull, the pull box distance must be at least how many times the trade size of the largest raceway?

4 times
6 times
8 times
10 times

NEC Reference: NEC 314.28(A)(2)

Question 7: Boxes must be installed so wiring inside can be reached without:

Removing part of the building
This is never a concern
Tearing down the whole wall
It does not matter

NEC Reference: NEC 314.29

Question 8: A panelboard must be marked with voltage, current rating, and:

Number of phases
The buyer's address
No marking is required
The store name

NEC Reference: NEC 408.30

Question 9: Circuits at a panelboard must be arranged so they do not overload the:

Supply conductors or bus
Building foundation
Owner's budget
Nothing, it does not matter

NEC Reference: NEC 408.3(A)

Question 10: Each grounded conductor in a panelboard should generally terminate at:

Its own individual terminal
Any shared terminal
No terminal at all
It does not matter

NEC Reference: NEC 408.41

Question 11: Which of the following is a recognized equipment grounding conductor type?

Rigid metal conduit
A garden hose
A wood beam
A telephone wire

NEC Reference: NEC 250.118

Question 12: An isolated ground receptacle helps reduce which problem for sensitive equipment?

Electrical noise
Water leaks
Low voltage
It has no purpose

NEC Reference: NEC 250.146(D)

Question 13: An intersystem bonding termination at a service connects:

Communication system grounds
Nothing
Gas meter only
A lightning rod only

NEC Reference: NEC 250.94

Question 14: All grounding electrodes present at a building must be:

Bonded together
Kept separate
Reduced to one, and the rest removed
Ignored

NEC Reference: NEC 250.50

Question 15: A concrete-encased electrode needs at least 20 feet of rebar or copper wire, covered by at least how much concrete?

2 inches
1/4 inch
12 inches
No cover is stated

NEC Reference: NEC 250.52(A)(3)

Question 16: A metal underground water pipe qualifies as an electrode with at least what length in the earth?

2 feet
10 feet
50 feet
Any length

NEC Reference: NEC 250.52(A)(1)

Question 17: A supplemental ground rod must be spaced from the first rod by at least:

2 feet
6 feet
10 feet
20 feet

NEC Reference: NEC 250.53(A)(3)

Question 18: A single ground rod tests above 25 ohms resistance to earth. What must be done?

Add a supplemental electrode
Nothing further is needed
Remove the rod completely
Shut off the service

NEC Reference: NEC 250.53(A)(2)

Question 19: Which of the following is an approved method to make a grounding connection?

Exothermic welding
Solder alone
Tape alone
No method is approved

NEC Reference: NEC 250.8

Question 20: Metal ductwork that could become energized must be bonded to:

The service equipment or grounding system
It is never bonded
A tree root
The phone company

NEC Reference: NEC 250.104(C)

Question 21: Where several disconnects share one set of service conductors, the grounded conductor connects to the grounding system at:

Only one point
Every disconnect separately
It does not matter
No connection is made

NEC Reference: NEC 250.24(A)(4)

Question 22: NM cable is not permitted to be:

Embedded in poured concrete
Used in a wall cavity
Fished through a wall
Run in an attic

NEC Reference: NEC 334.12

Question 23: A motor has a normal (under 1.15) service factor. What is the maximum overload setting?

100 %
115 %
125 %
150 %

NEC Reference: NEC 430.32(A)(1)

Question 24: A motor disconnect must be rated at least what percent of the motor full-load current?

100 %
115 %
125 %
150 %

NEC Reference: NEC 430.110(A)

Question 25: Overcurrent protection sizing rules for transformers are found in:

NEC 450.3
NEC 90.1
NEC 300.1
No section applies

NEC Reference: NEC 450.3

Question 26: A fixed generator must have:

A disconnecting means
No disconnect at all
A padlock only
A fire extinguisher only

NEC Reference: NEC 445.18

Question 27: Class II hazardous (combustible dust) locations are divided into which groups?

Groups E, F, and G
Groups A, B, C, and D
Groups 1 and 2
There are no groups

NEC Reference: NEC 500.6(B)

Question 28: A sign disconnect not within sight of the sign must be:

Lockable in the open position
Left unlocked
Removed entirely
Not required

NEC Reference: NEC 600.6

Question 29: A receptacle for HVAC servicing must be within what distance of the equipment?

10 feet
25 feet
50 feet
100 feet

NEC Reference: NEC 210.63

Question 30: Which of the following is an accepted source for a legally required standby system?

A generator set
A garden hose
A telephone line
No source is acceptable

NEC Reference: NEC 701.12

NEC 2023 Code Questions Practice Test 12

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NEC 2023 Code Questions Practice Test 12

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NEC 2023 Code Questions Practice Test 12 — Question List

Question 1: A switch or receptacle on one strap counts as how many conductors in box fill?

Question 2: One or more internal cable clamps in a box add how many conductors to the fill calculation?

Question 3: Each 10 AWG conductor in a box fill calculation needs a volume allowance of:

Question 4: In a wood wall, an outlet box can be set back from the finished surface by no more than:

Question 5: For a straight pull, a pull box must be at least how many times the trade size of the largest raceway?

Question 6: For an angle pull, the pull box distance must be at least how many times the trade size of the largest raceway?

Question 7: Boxes must be installed so wiring inside can be reached without:

Question 8: A panelboard must be marked with voltage, current rating, and:

Question 9: Circuits at a panelboard must be arranged so they do not overload the:

Question 10: Each grounded conductor in a panelboard should generally terminate at:

Question 11: Which of the following is a recognized equipment grounding conductor type?

Question 12: An isolated ground receptacle helps reduce which problem for sensitive equipment?

Question 13: An intersystem bonding termination at a service connects:

Question 14: All grounding electrodes present at a building must be:

Question 15: A concrete-encased electrode needs at least 20 feet of rebar or copper wire, covered by at least how much concrete?

Question 16: A metal underground water pipe qualifies as an electrode with at least what length in the earth?

Question 17: A supplemental ground rod must be spaced from the first rod by at least:

Question 18: A single ground rod tests above 25 ohms resistance to earth. What must be done?

Question 19: Which of the following is an approved method to make a grounding connection?

Question 20: Metal ductwork that could become energized must be bonded to:

Question 21: Where several disconnects share one set of service conductors, the grounded conductor connects to the grounding system at:

Question 22: NM cable is not permitted to be:

Question 23: A motor has a normal (under 1.15) service factor. What is the maximum overload setting?

Question 24: A motor disconnect must be rated at least what percent of the motor full-load current?

Question 25: Overcurrent protection sizing rules for transformers are found in:

Question 26: A fixed generator must have:

Question 27: Class II hazardous (combustible dust) locations are divided into which groups?

Question 28: A sign disconnect not within sight of the sign must be:

Question 29: A receptacle for HVAC servicing must be within what distance of the equipment?

Question 30: Which of the following is an accepted source for a legally required standby system?

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