NABCEP - Certified North American Board of Certified Energy Practitioners Specialist NEC Article 690 Applications Questions and Answers

Question 1

According to NEC Article 690, which of the following is a primary requirement for the location of a PV system disconnecting means?

Accepted Answer

It must be installed in a readily accessible location.

Answer

NEC 690.13 mandates that the PV system disconnecting means be installed in a 'readily accessible location'. This ensures that first responders and qualified personnel can quickly and safely de-energize the system without needing ladders or removing obstacles.

Question 2

A rooftop PV system is being installed on a single-family dwelling. Per NEC 690.12, what are the voltage and time limitations for controlled conductors *inside* the array boundary after rapid shutdown is initiated?

Accepted Answer

80 volts within 30 seconds

Answer

NEC 690.12(B)(2) requires that for PV systems on buildings, controlled conductors inside the array boundary shall be limited to not more than 80 volts within 30 seconds of initiating rapid shutdown. This is a critical safety measure for firefighters.

Question 3

When calculating the required ampacity for PV source circuit conductors, what multiplier is applied to the module's short-circuit current (Isc)?

Accepted Answer

125%

Answer

NEC 690.8(A)(1) requires that the maximum current for sizing conductors and overcurrent protection be calculated as 125% of the PV module's short-circuit current (Isc) to account for periods of higher-than-standard irradiance.

Question 4

Which of the following is required by NEC Article 690 regarding the grounding of a grid-tied PV system installed on a building?

Accepted Answer

Exposed non-current-carrying metal parts, like module frames and racking, must be bonded and connected to an equipment grounding conductor.

Answer

NEC 690.43 requires that exposed non-current-carrying metal parts of the PV system, including module frames, racking, and enclosures, must be bonded together and connected to an equipment grounding conductor (EGC) to create a safe path for fault current. While a separate grounding electrode is sometimes used, it is not always required and the system EGC often connects to the building's existing grounding electrode system.

Question 5

An installer is running PV source circuits from a rooftop array through the attic to a string inverter in the garage. According to NEC 690.31, which wiring method is typically required once the conductors penetrate the building?

Accepted Answer

The conductors must be installed in a metallic raceway or be a Type MC cable.

Answer

NEC 690.31(C)(1) generally requires that when PV source or output circuits penetrate a building, they must be installed in a metal raceway, such as EMT, or be a metal-clad (Type MC) cable from the point of penetration to the first readily accessible disconnecting means. This provides physical protection and a grounded path for the conductors inside the building.

(NABCEP) Certified North American Board of Certified Energy Practitioners Specialist Practice Test

(NABCEP) Certified North American Board of Certified Energy Practitioners Specialist Practice Test

NABCEP - Certified North American Board of Certified Energy Practitioners Specialist NEC Article 690 Applications Questions and Answers