NABCEP Code Requirements 5 — Questions and Answers
Question 1: Under NEC 690.7, when calculating open-circuit voltage for PV source circuits at low temperatures, installers must use which temperature coefficient?
- Temperature coefficient of power (Pmax)
- Temperature coefficient of Voc (negative value) (Correct answer)
- Temperature coefficient of Isc
- The NOCT-adjusted voltage value
Correct answer: Temperature coefficient of Voc (negative value)
NEC 690.7 requires using the module's negative temperature coefficient of Voc to determine maximum voltage at the lowest expected ambient temperature.
Question 2: Which listing standard covers PV module mounting and racking systems for structural and electrical compliance?
- UL 1703
- UL 2703 (Correct answer)
- UL 1741
- UL 9540
Correct answer: UL 2703
UL 2703 is the listing standard for PV mounting systems, mounting structures, and grounding/bonding components.
Question 3: Per NEC 690.13(B), the PV system disconnecting means must be located within sight of, and within how many feet of, the inverter it serves?
- 6 feet
- 10 feet
- 50 feet (Correct answer)
- No distance limit if lockable
Correct answer: 50 feet
NEC 690.13(B) requires the disconnecting means to be within sight and within 50 feet of the inverter.
Question 4: IEEE 1547-2018 sets requirements for distributed energy resource interconnection. Which of the following is a new requirement compared to older versions?
- Anti-islanding protection
- Ride-through capability during voltage and frequency disturbances (Correct answer)
- Disconnection at 60Hz
- Net metering billing compliance
Correct answer: Ride-through capability during voltage and frequency disturbances
IEEE 1547-2018 added mandatory voltage and frequency ride-through requirements so DER systems support grid stability instead of immediately tripping.
Question 5: Under NEC 690.35, ungrounded PV systems must be equipped with a ground-fault protection device that does which of the following?
- Disconnects only the array when a ground fault is detected
- Indicates and interrupts the fault, and may disconnect the array (Correct answer)
- Automatically resets after clearing the fault
- Monitors only; disconnection is optional for ungrounded systems
Correct answer: Indicates and interrupts the fault, and may disconnect the array
NEC 690.35 requires ungrounded systems to have GFPD that detects, indicates, and interrupts ground faults in the array.
Question 6: When a string inverter's output is connected to a load center using a back-fed breaker, and the panel busbar is rated 200A with a 200A main breaker, what is the maximum allowable rating of the back-fed breaker per NEC 705.12?
- 20A
- 40A (Correct answer)
- 60A
- 80A
Correct answer: 40A
120% of 200A = 240A; 240A minus the 200A main = 40A maximum for the back-fed breaker.
Question 7: Which NEC section requires that PV source and output circuits be kept separate from each other and from other wiring systems, unless a specific exception applies?
- NEC 690.4(B)
- NEC 690.31(A)
- NEC 690.4(C) (Correct answer)
- NEC 690.9(B)
Correct answer: NEC 690.4(C)
NEC 690.4(C) requires PV system wiring to be separated from other non-PV wiring unless they share an identified raceway or enclosure.
NABCEP Code Requirements 5
Under NEC 690.7, when calculating open-circuit voltage for PV source circuits at low temperatures, installers must use which temperature coefficient?