FREE Licensed Electrical Contractor Code, Theory, and Calculations Questions and Answers Flashcards
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Read the first 6 FREE Licensed Electrical Contractor Code, Theory, and Calculations Questions and Answers flashcards as text
What is the standard unit load per square foot used for general lighting in office buildings per the NEC?
Answer: 3.5 VA
NEC Table 220.12 specifies a unit load of 3.5 VA per square foot for general lighting in office buildings.
How many current-carrying conductors can occupy a single conduit before derating factors must be applied per the NEC?
Answer: 3
Ampacity adjustment factors from NEC Table 310.15(C)(1) apply when more than 3 current-carrying conductors are in a single raceway.
What is the power factor of a purely resistive AC circuit?
Answer: 1.0
A purely resistive AC circuit has a power factor of 1.0 because voltage and current are perfectly in phase.
Per the NEC, what is the minimum height above a rooftop for service drop conductors with a roof slope greater than 4 inches in 12 inches?
Answer: 3 feet
NEC 230.24(A) permits a reduction to 3 feet of clearance above a roof with a slope greater than 4 inches in 12 inches.
What is the total impedance of a series RLC circuit with R = 30 ohms, XL = 50 ohms, and XC = 10 ohms?
Answer: 50 ohms
Total impedance is calculated as Z = sqrt(R² + (XL - XC)²) = sqrt(900 + 1600) = 50 ohms.
What is the maximum number of 90-degree bends permitted between pull points in a conduit run per the NEC?
Answer: 4
NEC 358.26 limits conduit runs to a maximum of 360 degrees of total bends (equivalent to four 90-degree bends) between pull points.