These NEC wiring methods and raceway practice questions cover Chapter 3 — EMT, IMC, RMC, PVC, MC and NM cable. Wiring methods questions are mostly about two things: where you are allowed to use something, and how often you have to support it. Chapter 3 gives every method its own article, and they are laid out the same way — uses permitted, uses not permitted, then securing and supporting. Once you know that pattern you can find any answer in the book in under a minute, which is the whole skill the exam is testing.
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Written by Kevin, a licensed
Michigan master electrician — 26 years in the trade and 17 of them as an electrical
inspector. Every answer below names the NEC section it comes from, so you learn where to
look it up rather than memorising it.
Exam tipSupport spacing is the most commonly missed group here. Learn the ones that break the pattern — EMT at 10 ft, NM at 4½ ft, MC at 6 ft — and the box-offset allowances at each end.
Tap an answer to see whether you got it right, the code section it comes
from, and the reasoning worked out in full. Nothing to sign up for.
Question 1Expansion Fittings
An outdoor PVC schedule 40 runs 150 ft down a wall with a temperature change of 0°F to 90°F. What is the expansion?
Correct answer: A. 5.47 in
NEC 352.44
Rule — thermal expansion of PVC (352.44)
PVC grows and shrinks with temperature. Look up the expansion per 100 ft for your temperature change in Table 352.44(A), then scale to the run length.
Step 1 — temp change 90 °F → Table 352.44(A)
3.65 in. per 100 ft
Step 2 — scale to 150 ft
3.65 × (150 ÷ 100) = 5.47 in.
≈ 5.47 in.
How to do it
The table is per 100 ft, so multiply by (your length ÷ 100). Long outdoor PVC runs need an expansion fitting so the pipe doesn't buckle or pull apart.
Common mistakes
Forgetting to scale from 100 ft to the actual length.
Using the temperature itself instead of the change (Δ°F).
Question 2Raceways & Wiring Methods
What temperature column is NM wire sized from?
Correct answer: C. 60*c
NEC Table 310.16
NM cable is sized from the 60°C column of Table 310.16 (334.80) — even though its conductors may be 90°C rated.
Answer: the 60°C column.
Question 3Expansion Fittings
PVC run that is 100ft on an outside building with a temp change of 15F what the expansion
Correct answer: B. .61
NEC Table 352.44(A)
Rule — thermal expansion of PVC (352.44)
PVC moves with temperature. Look up the expansion per 100 ft for your temperature change in Table 352.44(A), then scale to the run length.
Step 1 — temp change 15 °F → Table 352.44(A)
0.61 in. per 100 ft
Step 2 — scale to 100 ft
0.61 × (100 ÷ 100) = 0.61 in.
≈ 0.61 in.
How to do it
The table is per 100 ft, so multiply by (your length ÷ 100). Here the run is exactly 100 ft, so the factor is 1 and the answer equals the table value. Long outdoor runs need an expansion fitting.
Common mistakes
Using the temperature itself instead of the change (Δ°F).
Forgetting to scale from 100 ft to the actual length.
Question 4Expansion Fittings
Expansion of a 150 ft PVC run with a 15 °F temperature change?
Correct answer: B. 0.91 in
NEC 352.44 — PVC expansion fittings
PVC thermal expansion (352.44)
Step 1 — Look up the temperature change in Table 352.44(A). A 15 F change = 0.61 in. per 100 ft
Step 2 — Length factor
150 ft / 100 ft = 1.5
Step 3 — Multiply
0.61 x 1.5 = 0.91 in
Expansion is about 0.91 in.
352.44 — PVC expansion fittings
0.91 in
How to do it
Look up the expansion per 100 ft for your temperature CHANGE in Table 352.44(A), then scale by (run length ÷ 100). Long outdoor runs need an expansion fitting.
Common mistakes
Using the temperature itself instead of the change (Δ°F).
Forgetting to scale from 100 ft to the actual run length.
Question 5Raceways & Wiring Methods
The tightest bend allowed for type NM cable is a radius of how many times the diameter of the cable?
Correct answer: A. 5
NEC 334.24
5 — NEC 334.24
Question 6Raceways & Wiring Methods
What is the maximum distance between support for standard size 2in schedule 40 PVC?
Correct answer: B. 5ft
NEC 352.30(B)
5ft — NEC 352.30(B)
Question 7Raceways & Wiring Methods
What size NM wire can be attached to the underside of a floor joist in a crawl space?
Correct answer: A. #8
NEC 334.15(C)
#8 — NEC 334.15(C)
Question 8Raceways & Wiring Methods
An outlet box shall be flush or set back not more than ______.
Correct answer: A. .25”
NEC 314.20
.25” — NEC 314.20
Question 9Raceways & Wiring Methods
What is the smallest size conductor that can be installed in parallel?
Correct answer: C. 1/0
NEC 310.10(G)(1)
1/0 — NEC 310.10(G)(1)
Question 10Raceways & Wiring Methods
Cables rated above _________ must be shielded.
Correct answer: B. 2000V
NEC 315.44
2000V — NEC 315.44
These are 10 of 803 questions
The full course carries 654 code and calculation questions plus 149 photo questions taken on real job sites — my own photographs from 17 years of electrical inspections. Every one of them is worked out like the ones above.
NEC 2023 and NEC 2026 both included, switch between them any time
Every question names the code section, so you learn to find it in the book
The whole course reads itself out loud, with the words highlighted as they are spoken
Timed 80-question practice test built like the real exam
Video lessons, drive-along audio and flash cards that bring back what you miss