NABCEP - Certified North American Board of Certified Energy Practitioners Specialist Electrical Component Inspection Questions and Answers

Question 1

During a visual inspection of a newly installed string inverter, which of the following findings would be the MOST immediate cause for concern and require correction before commissioning?

Accepted Answer

There is less than the manufacturer-specified clearance for ventilation around the unit.

Answer

Inadequate clearance around an inverter can lead to overheating, which significantly reduces its efficiency and lifespan, and can cause a complete shutdown or failure. While missing labels and conduit routing are code violations that must be corrected, improper ventilation poses an immediate operational risk to the equipment itself.

Question 2

An inspector is examining the DC combiner box for a 600V nominal system. Which of the following observations is a clear violation of standard electrical practice and the NEC?

Accepted Answer

Unused openings in the enclosure are sealed with duct tape.

Answer

According to the National Electrical Code (NEC), all unused openings in electrical enclosures must be closed with listed plugs or plates to maintain the enclosure's integrity and environmental rating (e.g., NEMA 3R for outdoor use). Duct tape is not a listed or permanent solution and would be a violation.

Question 3

When inspecting exposed single-conductor cables (PV Wire/USE-2) within a rooftop solar array, what is a critical installation requirement according to NEC 690.31?

Accepted Answer

Conductors must be secured and supported to prevent damage from wind and abrasion.

Answer

NEC 690.31(C)(1) requires that exposed single conductors be supported and secured to prevent damage from wind, ice, and physical abrasion against the racking or roof surface. Proper wire management is crucial to prevent insulation breakdown, which could lead to ground faults or fires over the system's lifetime.

Question 4

A technician is inspecting a junction box on the back of a PV module and notices that the sealing gasket is cracked and displaced, with evidence of moisture ingress. What is the most likely consequence of this defect?

Accepted Answer

Corrosion of terminals and potential bypass diode failure.

Answer

Moisture entering a junction box can cause corrosion on the electrical terminals and damage the bypass diodes. This can lead to increased resistance, heat buildup, reduced module output, and even create a fire hazard. The other options are not direct consequences of a compromised junction box seal.

Question 5

During a commissioning inspection, you are verifying the overcurrent protection for the inverter's AC output circuit. If the inverter's maximum continuous output current is 32A, what is the minimum standard size for the back-fed circuit breaker in the main panel, per NEC requirements?

Accepted Answer

40A

Answer

According to NEC 705.12(B) and 690.8(B), the overcurrent protection device for the inverter's output circuit must be sized to at least 125% of the maximum continuous output current. Therefore, 32A * 1.25 = 40A. This is a standard breaker size and is the minimum required.

(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 Electrical Component Inspection Questions and Answers