Electrical Safety & Code Compliance Flashcards

In a 3-phase 4-wire wye system, what voltage exists between any two hot conductors?

Answer: 208V

In a 208Y/120V wye system, line-to-line voltage is 120V × √3 ≈ 208V between any two phase conductors.

Which NEC article governs the installation of branch circuits?

Answer: Article 210

NEC Article 210 covers branch circuits, including ratings, required outlets, and GFCI/AFCI requirements.

An AFCI breaker is designed primarily to protect against which type of hazard?

Answer: Arcing faults that can ignite fires

Arc Fault Circuit Interrupters detect the unique electrical signature of dangerous arcing faults that can ignite fires without tripping standard breakers.

What is the maximum voltage drop allowed on a branch circuit per NEC recommended practice (informational note)?

Answer: 3%

NEC 210.19(A) informational note recommends limiting branch circuit voltage drop to 3% for best performance.

A worker must use rubber insulating gloves rated for 1,000V. According to ASTM standards, what class are these gloves?

Answer: Class 0

ASTM Class 0 rubber insulating gloves are rated for maximum use voltage of 1,000V AC (1,500V DC).

Under NEC 300.5, the minimum burial depth for a 120V residential circuit in a rigid metal conduit (RMC) is:

Answer: 6 inches

NEC Table 300.5 allows only 6 inches of cover for circuits in rigid metal conduit due to its superior mechanical protection.

Which document defines the national minimum safety standard for electrical installations in the United States?

Answer: NFPA 70 (National Electrical Code)

NFPA 70, the National Electrical Code (NEC), is the nationally recognized minimum safety standard for electrical installations in the US.