NABCEP Electrical Component Inspection 2

Question 1

During a PV system inspection, you notice the output circuit conductors are routed through metal conduit with no separation from the grounding electrode conductor. What is the primary concern?

Accepted Answer

Induced currents may cause heating in the metallic conduit

Answer

Voltage drop will increase significantly

Answer

The grounding electrode conductor must always be in PVC

Answer

No concern exists as long as the conduit is bonded

Question 2

A technician inspects a string inverter and finds the DC input voltage is 15% above the inverter's maximum rated input voltage. What is the most likely cause?

Accepted Answer

Ambient temperature is unusually low, increasing Voc

Answer

Modules are operating at STC temperature

Answer

The inverter MPPT range is too narrow

Answer

The array is undersized for the inverter

Question 3

When inspecting a ground-mounted PV array, you observe rust staining on the mounting rails below the module clamps. What does this most likely indicate?

Accepted Answer

Galvanic corrosion between dissimilar metals at the clamp interface

Answer

The modules are generating excessive heat

Answer

The array has been exposed to excessive UV radiation

Answer

The clamps are overtorqued causing metal fatigue

Question 4

An inspector finds that the AC disconnect is labeled with a voltage rating of 240V but is installed on a 208V three-phase system. What is the appropriate finding?

Accepted Answer

This is acceptable since 240V exceeds 208V

Answer

The disconnect must be replaced with a 208V-rated unit

Answer

The disconnect is acceptable only if it is OCPD-rated

Answer

The disconnect voltage rating must exactly match system voltage

Question 5

During a commissioning inspection, you identify that the PV source circuit fuses are rated at 20A but the module's maximum series fuse rating (Isc × 1.25 × 1.25) calculates to 15A. What action is required?

Accepted Answer

Replace the fuses with properly sized 15A fuses

Answer

No action needed if the wire is rated for 20A

Answer

Add a parallel bypass diode to each module

Answer

Increase the number of modules in the string

Question 6

A rooftop PV system inspection reveals that module frames are bonded using module-to-module bonding washers but the first and last modules in each row are not connected to the equipment grounding conductor. What code requirement is violated?

Accepted Answer

NEC 690.43 requiring all exposed metal parts to be grounded

Answer

NEC 690.35 covering ungrounded systems

Answer

NEC 705.12 covering point of connection

Answer

NEC 230.24 covering clearances

Question 7

When inspecting combiner box connections, a technician measures a 2V voltage drop across a string fuse under load. The fuse is rated for the correct ampacity. What does this reading indicate?

Accepted Answer

A loose or corroded fuse connection creating excessive resistance

Answer

Normal operation within tolerance

Answer

The string is producing higher than expected current

Answer

The fuse has a lower voltage rating than required