Overcurrent Protection Flashcards
6 cards from real TN LLE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Overcurrent Protection flashcards as text
Per NEC 230.90(A), what is the maximum rating of the service overcurrent device relative to the conductor ampacity?
Answer: Must not exceed the allowable ampacity of the service-entrance conductors
NEC 230.90(A) requires the service overcurrent device rating to not exceed the allowable ampacity of the service-entrance conductors.
What is the purpose of ground-fault protection of equipment (GFPE) per NEC 230.95?
Answer: To detect ground faults and disconnect the service to prevent equipment damage and fire on solidly grounded wye services of more than 150V to ground and 1000A or more
NEC 230.95 requires GFPE on solidly grounded wye services exceeding 150V to ground and 1000A or more to detect arcing ground faults that can cause fires.
Per NEC 240.83(D), what marking is required on circuit breakers used to switch 120V or 277V fluorescent lighting?
Answer: SWD (Switching Duty)
NEC 240.83(D) requires circuit breakers used for switching fluorescent lighting to be marked SWD (Switching Duty).
What is the NEC requirement for coordination between overcurrent devices in a series (selective coordination)?
Answer: Coordination is required for certain critical systems like emergency, legally required standby, and healthcare systems
NEC sections 700.32, 701.27, and 517.26 require selective coordination for emergency systems, legally required standby systems, and healthcare essential electrical systems.
Per NEC 240.86, what is the maximum distance for a series-rated system where the line-side device protects load-side devices?
Answer: No distance limit as long as the combination is tested and listed
NEC 240.86 does not impose a specific distance limit. The series combination must be tested and listed by a testing laboratory.
What type of overcurrent protection is required for flexible cords and fixture wires per NEC 240.5?
Answer: Overcurrent protection based on NEC Table 400.5(A)(1) cord ampacity values
NEC 240.5 addresses overcurrent protection for flexible cords and fixture wires, referencing Table 400.5 for cord ampacity.