Electrical System Design & Installation 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 Electrical System Design & Installation flashcards as text
When sizing conductors for a continuous load, the conductor ampacity must be at least what percentage of the load's ampere rating per NEC 210.19?
Answer: 125%
NEC 210.19(A)(1) requires conductors for continuous loads to be sized at 125% of the continuous load ampere rating.
Which conductor material requires anti-oxidant compound when terminating at devices or equipment?
Answer: Aluminum
Aluminum conductors oxidize at connections, so anti-oxidant compound is required to ensure a reliable, low-resistance termination.
A 240V single-phase motor draws 28 amperes at full load. The minimum branch circuit conductor size using 75°C copper wire (THWN) is:
Answer: 8 AWG
Motor branch circuits must be sized at 125% of FLA: 28A × 1.25 = 35A, requiring 8 AWG THWN copper rated at 50A.
Which NEC article governs the installation of electrical systems in hazardous (classified) locations?
Answer: Article 500
NEC Article 500 covers hazardous (classified) locations, defining Class I, II, and III divisions and zones.
In a delta-wye transformer installation, which winding configuration provides a neutral conductor on the secondary side?
Answer: Delta primary, wye secondary
A delta-wye configuration provides a neutral on the wye secondary, enabling 3-phase 4-wire distribution systems.
What is the maximum distance a disconnecting means can be located from the point of entrance for a service in a building?
Answer: The first point of entrance to the building
NEC 230.70 requires the service disconnecting means to be installed at the nearest point of entrance of the service conductors inside or outside the building.
For a 3-phase, 4-wire wye system rated 208Y/120V, what is the voltage measured between any phase conductor and the neutral?
Answer: 120V
In a 208Y/120V system, 120V is the phase-to-neutral voltage and 208V is the phase-to-phase voltage.