CEA Wiring Methods and Materials 2 — Questions and Answers
Question 1: What is the maximum number of 90-degree bends allowed in a single run of conduit between pull points according to the NEC?
- Two 90-degree bends
- Three 90-degree bends
- Four 90-degree bends (Correct answer)
- Five 90-degree bends
Correct answer: Four 90-degree bends
NEC 358.26 limits conduit runs to a maximum of four quarter bends (360 degrees total) between pull points.
Question 2: Which wiring method is specifically listed for use in wet locations and is identified by a 'W' rating?
- THHN
- TW (Correct answer)
- XHHW
- THW
Correct answer: TW
TW conductors have a 'W' suffix indicating they are rated for wet locations, with a 60°C temperature rating.
Question 3: When installing flexible metal conduit (FMC), what is the minimum trade size permitted for general use?
- 3/8 inch
- 1/2 inch (Correct answer)
- 3/4 inch
- 1 inch
Correct answer: 1/2 inch
NEC 348.20 permits 3/8-inch FMC only in limited applications; 1/2-inch is the minimum for general use.
Question 4: Rigid PVC conduit (Schedule 40) must be supported at intervals not exceeding how many feet for trade sizes 1/2 to 1 inch?
- 2 feet
- 3 feet (Correct answer)
- 4 feet
- 5 feet
Correct answer: 3 feet
NEC 352.30 requires Schedule 40 PVC conduit 1/2 to 1 inch to be supported every 3 feet.
Question 5: Which conductor insulation type is rated for use in both wet and dry locations at 90°C?
- TW
- THW
- THWN-2 (Correct answer)
- THHN
Correct answer: THWN-2
THWN-2 is rated 90°C in both wet and dry locations, making it one of the most versatile insulation types.
Question 6: What material is type AC cable (armored cable) armor made from?
- Aluminum interlocked tape
- Steel spiral wrap (Correct answer)
- PVC jacketed steel
- Copper braid
Correct answer: Steel spiral wrap
Type AC cable uses a spiral-wound steel armor that provides mechanical protection and serves as a ground return path.
Question 7: When using metal wireways, the sum of cross-sectional areas of all contained conductors must not exceed what percentage of the wireway's interior cross-section?
- 20%
- 30%
- 40% (Correct answer)
- 50%
Correct answer: 40%
NEC 376.22 limits conductors in metal wireways to 20% fill at splices/taps, and 40% fill for through-conductors.
CEA Wiring Methods and Materials 2
What is the maximum number of 90-degree bends allowed in a single run of conduit between pull points according to the NEC?