Wiring Methods and Materials Flashcards

What is the maximum number of 90-degree bends allowed in a single run of conduit between pull points according to the NEC?

Answer: Four 90-degree bends

NEC 358.26 limits conduit runs to a maximum of four quarter bends (360 degrees total) between pull points.

Which wiring method is specifically listed for use in wet locations and is identified by a 'W' rating?

Answer: TW

TW conductors have a 'W' suffix indicating they are rated for wet locations, with a 60°C temperature rating.

When installing flexible metal conduit (FMC), what is the minimum trade size permitted for general use?

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.

Rigid PVC conduit (Schedule 40) must be supported at intervals not exceeding how many feet for trade sizes 1/2 to 1 inch?

Answer: 3 feet

NEC 352.30 requires Schedule 40 PVC conduit 1/2 to 1 inch to be supported every 3 feet.

Which conductor insulation type is rated for use in both wet and dry locations at 90°C?

Answer: THWN-2

THWN-2 is rated 90°C in both wet and dry locations, making it one of the most versatile insulation types.

What material is type AC cable (armored cable) armor made from?

Answer: Steel spiral wrap

Type AC cable uses a spiral-wound steel armor that provides mechanical protection and serves as a ground return path.

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?

Answer: 40%

NEC 376.22 limits conductors in metal wireways to 20% fill at splices/taps, and 40% fill for through-conductors.