Wiring Methods and Materials Flashcards
7 cards from real Licensed Electrical Contractor practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Wiring Methods and Materials flashcards as text
When installing conductors in parallel, each parallel conductor must be:
Answer: The same size, same insulation type, same length, and same material
NEC 310.10(H) requires parallel conductors to be the same size, same insulation type, same length, same conductor material, and terminated in the same manner to ensure equal current sharing.
Which of the following is the correct fill percentage for a new conduit installation with 4 or more conductors?
Answer: 31%
NEC Chapter 9, Table 1 limits conduit fill to 31% of the cross-sectional area when 4 or more conductors are installed.
Type SE (service-entrance) cable used as an interior branch circuit wiring method must have all conductors:
Answer: Insulated, including the neutral
When Type SE cable is used for interior branch circuits (not as service entrance), all conductors including the neutral must be insulated per NEC 338.10(B)(4).
What is the minimum trade size of rigid metal conduit required to contain three 1/0 AWG THHN conductors and one 6 AWG THHN EGC?
Answer: 1-1/4 inch
Using NEC Chapter 9 tables, the combined area of three 1/0 AWG and one 6 AWG THHN conductors at 40% fill requires a minimum 1-1/4 inch RMC.
Which of the following statements about flexible metal conduit (FMC) is correct?
Answer: FMC is permitted as the EGC only when the circuit is 20A or less and the length is 6 feet or less
NEC 348.60 permits FMC to serve as the EGC for circuits rated 20 amperes or less when the length of the FMC does not exceed 6 feet and the fittings are listed for grounding.
Conductors installed in a raceway exposed to direct sunlight on rooftops must have their ampacity adjusted by adding a temperature correction factor. What additional temperature adder applies per NEC 310.15(B)(3)(c) for conduits on rooftops?
Answer: 17°C (33°F)
NEC 310.15(B)(3)(c) requires an adder of 17°C (33°F) to the ambient temperature for conductors in raceways exposed to direct sunlight on or above a rooftop.
When must conductors in a raceway be considered current-carrying for the purpose of conduit fill derating?
Answer: Neutral conductors on 3-wire, single-phase systems carry only unbalanced current and are not counted
NEC 310.15(E) excludes the neutral conductor of a 3-wire single-phase circuit from the count of current-carrying conductors because it only carries unbalanced load current.