Code, Theory, and Calculations 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 Code, Theory, and Calculations flashcards as text
What NEC section governs the installation of conductors in raceways, and what is the maximum fill percentage for a single conductor in a conduit?
Answer: NEC 300.17 — 53%
NEC 300.17 references Chapter 9 Table 1, which allows 53% fill for a single conductor in a conduit.
What is the reactance of a 60 Hz circuit with an inductance of 0.5 H?
Answer: 188.5 Ω
Inductive reactance XL = 2πfL = 2π × 60 × 0.5 ≈ 188.5 Ω.
Under NEC 210.8(A), GFCI protection is required for all 125 V, 15 A and 20 A receptacles in which residential location?
Answer: All outdoor locations
NEC 210.8(A) requires GFCI protection for all 125 V, 15 A and 20 A receptacles installed in outdoor locations of dwelling units.
A 480 V, 3-phase, 4-wire wye system has a line-to-neutral voltage of approximately:
Answer: 277 V
Line-to-neutral voltage = line voltage ÷ √3 = 480 ÷ 1.732 ≈ 277 V.
Per NEC 250.122, the minimum size equipment grounding conductor (EGC) for a circuit protected by a 200 A overcurrent device is:
Answer: 6 AWG copper
NEC Table 250.122 specifies a minimum 6 AWG copper EGC for circuits protected by overcurrent devices up to 200 A.
In a capacitive AC circuit, the current:
Answer: Leads the voltage by 90°
In a purely capacitive circuit, current leads voltage by 90° because the capacitor charges before the voltage peaks.
NEC 408.36 requires panelboards supplied by a 4-wire delta system to be labeled to indicate the:
Answer: High-leg (wild leg) conductor and its voltage to ground
NEC 408.36 requires the high-leg (wild leg) of a 4-wire delta system to be durably marked at the panelboard to indicate its higher voltage to ground (typically 208 V).