NABCEP Code Requirements 2 — Questions and Answers
Question 1: Under NEC Article 690, what is the maximum voltage permitted for PV source circuits in one- and two-family dwellings?
- 300V
- 600V
- 1000V (Correct answer)
- 1500V
Correct answer: 1000V
NEC 690.7 limits PV source and output circuit voltages to 1000V for one- and two-family dwellings.
Question 2: According to NEC 690.12, rapid shutdown of PV systems on buildings requires that PV system conductors outside the array boundary be de-energized to no more than how many volts within 30 seconds of rapid shutdown initiation?
- 0V
- 30V (Correct answer)
- 80V
- 120V
Correct answer: 30V
NEC 690.12 requires conductors outside the array boundary to be reduced to 30V or less within 30 seconds.
Question 3: Which NEC article specifically governs energy storage systems (ESS) such as battery systems used with solar PV?
- Article 480
- Article 690
- Article 706 (Correct answer)
- Article 702
Correct answer: Article 706
NEC Article 706 covers energy storage systems, including battery systems paired with solar PV.
Question 4: When sizing PV source circuit conductors, NEC 690.8 requires the conductor ampacity to be at least what percentage of the sum of the short-circuit currents of all parallel-connected PV modules?
- 100%
- 115%
- 125%
- 156.25% (Correct answer)
Correct answer: 156.25%
NEC 690.8(A)(1) requires conductors to carry 125% of Isc, and then the overcurrent device and conductor must be sized at 125% of that value, yielding 156.25% of Isc.
Question 5: Per NEC 690.31, PV wiring systems installed in raceways exposed to direct sunlight on rooftops must use conductors with a temperature rating of at least:
- 60°C
- 75°C
- 90°C (Correct answer)
- 105°C
Correct answer: 90°C
NEC 690.31(A) requires conductors in raceways exposed to sunlight on rooftops to be rated at least 90°C.
Question 6: According to NEC 690.64, a utility-interactive inverter output connection in a residence must be made at a dedicated circuit breaker; if the breaker is at the opposite end of the busbar from the main breaker, what is the key code concern?
- Arc flash labeling
- Busbar back-feed and the 120% rule (Correct answer)
- GFCI protection
- Grounding electrode conductor sizing
Correct answer: Busbar back-feed and the 120% rule
NEC 690.64 and 705.12 require that PV back-fed breakers plus the main breaker rating not exceed 120% of the busbar rating.
Question 7: Which document provides the installation standard that most jurisdictions adopt by reference, covering PV system installation best practices beyond the NEC's minimum electrical requirements?
- ASTM E1171
- UL 1703
- NFPA 855
- IFC / NFPA 1 fire codes (Correct answer)
Correct answer: IFC / NFPA 1 fire codes
The International Fire Code (IFC) and NFPA 1 set setback and access requirements for PV arrays on rooftops beyond NEC electrical rules.
NABCEP Code Requirements 2
Under NEC Article 690, what is the maximum voltage permitted for PV source circuits in one- and two-family dwellings?