NABCEP NEC Article 690 Applications 5 — Questions and Answers
Question 1: NEC 690.31(C) permits single-conductor cables listed and identified as PV wire for exposed outdoor wiring in the PV array. What additional requirement applies to these conductors?
- They must be run in conduit when exposed to sunlight
- They must be sunlight resistant and listed as PV wire for outdoor use (Correct answer)
- They must be stranded and at least 10 AWG
- They must be rated for 600 V minimum regardless of system voltage
Correct answer: They must be sunlight resistant and listed as PV wire for outdoor use
NEC 690.31(C) requires single-conductor wiring used in arrays to be listed PV wire rated as sunlight resistant for safe outdoor exposure.
Question 2: Under NEC 690.8(A), what is the calculated maximum current for a PV source circuit used to size conductors and overcurrent devices?
- The sum of the module short-circuit current ratings (Isc) at standard test conditions
- 125% of the module rated operating current (Imp)
- The sum of Isc values multiplied by 125% (Correct answer)
- The module open-circuit voltage divided by the minimum system resistance
Correct answer: The sum of Isc values multiplied by 125%
NEC 690.8(A) defines maximum circuit current as the sum of parallel source circuit Isc values, and conductors must be sized at 125% of this value.
Question 3: NEC 690.9 requires overcurrent protection for PV source and output circuits. When is overcurrent protection NOT required for a PV source circuit conductor?
- When the circuit is less than 10 ft in length
- When the ampacity of the conductor is greater than the maximum current it could receive from all parallel sources (Correct answer)
- When the module manufacturer specifies no fuse required
- When the conductor is in conduit
Correct answer: When the ampacity of the conductor is greater than the maximum current it could receive from all parallel sources
NEC 690.9(A) Exception allows omission of overcurrent protection when the conductor ampacity exceeds the maximum current from all connected parallel sources.
Question 4: According to NEC 690.53, a permanent label must be applied to the PV system disconnecting means. Which of the following is NOT required on this label?
- Maximum system voltage
- Maximum circuit current
- Maximum power point current (Imp) at STC (Correct answer)
- Open-circuit voltage (Voc)
Correct answer: Maximum power point current (Imp) at STC
NEC 690.53 requires the disconnect label to show system voltage, maximum circuit current, and open-circuit voltage, but does not require Imp to be listed.
Question 5: For PV systems over 1000 V, NEC 690 refers installers to which additional NEC article for supplementary requirements?
- Article 230
- Article 480
- Article 691 (Correct answer)
- Article 705
Correct answer: Article 691
NEC Article 691 covers large-scale PV systems operating above 1000 V and provides additional requirements beyond Article 690.
Question 6: NEC 690.54 requires a label at the utility interactive inverter indicating which of the following?
- The model and serial number of the inverter only
- That the inverter output is a 60 Hz source and indicating its rated ac output (Correct answer)
- The name of the installer and installation date
- The module-level power electronics specifications
Correct answer: That the inverter output is a 60 Hz source and indicating its rated ac output
NEC 690.54 requires the inverter to be labeled showing it is a 60 Hz source with its rated ac output to identify it as a power source for first responders.
Question 7: When NEC 690.31(B) permits PV system wiring to be installed in the same raceway as other systems, what condition must be met?
- All conductors must be the same voltage rating
- The conductors must be insulated for the maximum voltage of any conductor in the raceway (Correct answer)
- A physical separator must divide the PV conductors from other conductors
- PV conductors are never permitted in shared raceways
Correct answer: The conductors must be insulated for the maximum voltage of any conductor in the raceway
NEC 690.31(B) requires that when PV conductors share a raceway with conductors of other systems, all conductors must be insulated for the highest voltage present.
NABCEP NEC Article 690 Applications 5
NEC 690.31(C) permits single-conductor cables listed and identified as PV wire for exposed outdoor wiring in the PV array.
What additional requirement applies to these conductors?