NABCEP Installation & Safety 4 — Questions and Answers
Question 1: When installing a roof penetration for a conduit on a tile roof, what is the best practice to prevent water intrusion?
- Apply roofing caulk around the conduit only
- Use a purpose-made flashing boot sized for the conduit and integrate it under the tile course above (Correct answer)
- Install the conduit through the ridge cap
- Seal the penetration with expanding spray foam
Correct answer: Use a purpose-made flashing boot sized for the conduit and integrate it under the tile course above
A properly sized flashing boot integrated under the overlapping tile course above directs water away from the penetration and is the industry-standard watertight method.
Question 2: What hazard does crystalline silicon PV module glass pose if broken during installation?
- Release of toxic cadmium telluride dust
- Sharp glass shards and potential electrical exposure from energized cells (Correct answer)
- Ignition of the EVA encapsulant
- UV radiation exposure from the cell surface
Correct answer: Sharp glass shards and potential electrical exposure from energized cells
Broken crystalline silicon modules expose workers to sharp tempered glass shards and potentially energized cells, requiring gloves, eye protection, and careful handling.
Question 3: According to NEC 690.31, what is the maximum allowable length of exposed PV source or output circuit wiring outside a raceway on a rooftop?
- No limit if secured every 12 inches
- 6 feet between supports or enclosures (Correct answer)
- 3 feet
- 18 inches
Correct answer: 6 feet between supports or enclosures
NEC 690.31 allows PV wire to be exposed on a rooftop without a raceway but requires it to be secured every 6 feet and uses listed PV wire rated for exposure.
Question 4: What is the minimum height clearance required for a service-entrance conductor (SE cable) above a roof surface per NEC 230.24?
- 3 feet
- 8 feet
- 18 inches (Correct answer)
- 10 feet
Correct answer: 18 inches
NEC 230.24(B) allows service-entrance conductors to be as close as 18 inches above a roof surface when the service point is at the edge of the roof, to reduce blow-down hazards.
Question 5: Which condition makes a confined space 'permit-required' under OSHA 1910.146?
- The space is larger than 100 cubic feet
- The space has limited means of egress and contains a serious safety or health hazard (Correct answer)
- The space requires a ladder to enter
- The space is located underground
Correct answer: The space has limited means of egress and contains a serious safety or health hazard
A permit-required confined space has limited entry/exit and contains or has the potential to contain a serious hazard such as a hazardous atmosphere, engulfment, or entrapment risk.
Question 6: What does SDS stand for in the context of hazardous materials used during PV installation?
- System Design Specification
- Safety Data Sheet (Correct answer)
- Solar Derate Standard
- Structural Design Summary
Correct answer: Safety Data Sheet
A Safety Data Sheet (SDS) provides information on the properties, hazards, safe handling, and emergency procedures for a chemical or material.
Question 7: What is the purpose of anti-islanding protection in a grid-tied PV inverter?
- To prevent the PV system from operating at night
- To automatically disconnect the inverter from the grid when utility power fails, protecting line workers (Correct answer)
- To balance the load between multiple inverters
- To limit the system's export power to the contract limit
Correct answer: To automatically disconnect the inverter from the grid when utility power fails, protecting line workers
Anti-islanding protection shuts down the inverter when grid power fails to prevent the PV system from back-feeding the utility lines and endangering line workers making repairs.
NABCEP Installation & Safety 4
When installing a roof penetration for a conduit on a tile roof, what is the best practice to prevent water intrusion?