Electrical Systems in Construction Flashcards

What is the standard voltage for most residential electrical service in the United States?

Answer: 120/240V single-phase

Standard US residential service is 120/240V single-phase, providing 120V for outlets and 240V for large appliances.

Which wire color is used for the grounding conductor in standard US residential wiring?

Answer: Green or bare copper

Green insulated wire or bare copper conductor is the NEC-standard color code for equipment grounding conductors.

What does GFCI stand for in electrical construction?

Answer: Ground Fault Circuit Interrupter

GFCI stands for Ground Fault Circuit Interrupter, a device that detects current leakage to ground and trips within milliseconds to prevent electrocution.

According to the NEC, what is the maximum number of current-carrying conductors in a conduit before derating is required?

Answer: 3

NEC requires derating of conductor ampacity when more than 3 current-carrying conductors are bundled together in a raceway or cable.

What type of conduit is most commonly used outdoors and in wet locations for commercial construction?

Answer: PVC (Rigid Nonmetallic Conduit)

PVC rigid nonmetallic conduit resists moisture and corrosion, making it the preferred choice for outdoor and wet-location installations.

What is the minimum depth required for direct-burial electrical cable (UF cable) under a residential driveway?

Answer: 24 inches

NEC Table 300.5 requires UF cable buried under residential driveways to be at a minimum depth of 24 inches to protect against damage from vehicle loads.

Which document serves as the primary standard for electrical installations in construction in the United States?

Answer: NFPA 70 (National Electrical Code)

NFPA 70, the National Electrical Code (NEC), is the primary standard adopted by most US jurisdictions governing safe electrical installations in buildings.