NABCEP Installation & Safety 2 â Questions and Answers
Question 1: What is the minimum working space clearance required in front of electrical equipment rated 0-150V to ground per NEC 110.26?
- 2 feet
- 3 feet (Correct answer)
- 4 feet
- 6 feet
Correct answer: 3 feet
NEC 110.26 requires a minimum of 3 feet of clear working space in front of electrical equipment for systems rated 0-150V to ground.
Question 2: When installing a rooftop PV array, what is the primary purpose of required access pathways per the fire code?
- To allow workers to walk during installation
- To provide firefighters with safe roof access and ventilation points (Correct answer)
- To meet zoning setback requirements
- To ensure the modules can be cleaned easily
Correct answer: To provide firefighters with safe roof access and ventilation points
Fire codes mandate rooftop access pathways so firefighters can safely reach the roof and create ventilation openings during a fire emergency.
Question 3: Which PPE is required when working on energized DC circuits in a PV system?
- Latex gloves rated for 480V AC
- Insulated tools and appropriately rated insulating gloves (Correct answer)
- Standard leather work gloves
- Rubber-soled boots only
Correct answer: Insulated tools and appropriately rated insulating gloves
Working on energized DC circuits requires insulated tools and voltage-rated insulating gloves to prevent shock from the uninterruptible DC source.
Question 4: What is the maximum DC voltage rating of a PV system that can be installed on a one- or two-family dwelling per NEC 690.12?
- 300V
- 480V
- 600V (Correct answer)
- 1000V
Correct answer: 600V
NEC 690.12 limits PV system DC voltage on one- and two-family dwellings to 600V maximum to reduce arc-flash and shock hazards.
Question 5: A solar installer notices that the roof decking is soft and spongy in one area. What should the installer do?
- Continue installation and note it in the project closeout
- Avoid that area and continue elsewhere on the roof
- Stop work and notify the project manager or structural engineer (Correct answer)
- Reinforce the area with additional lag screws
Correct answer: Stop work and notify the project manager or structural engineer
Soft or spongy decking indicates potential structural failure; work must stop and a qualified professional must assess the roof before installation continues.
Question 6: What does OSHA 1926.502 require when workers are exposed to falls of 6 feet or more on residential construction sites?
- A safety observer must be present at all times
- Fall protection must be provided such as guardrails, safety nets, or personal fall arrest systems (Correct answer)
- Workers must wear hard hats only
- A spotter must stand below the work area
Correct answer: Fall protection must be provided such as guardrails, safety nets, or personal fall arrest systems
OSHA 1926.502 mandates fall protection systemsâguardrails, safety nets, or personal fall arrest systemsâfor residential workers exposed to falls of 6 feet or greater.
Question 7: When is an arc-fault circuit interrupter (AFCI) required in a residential PV system per NEC 690.11?
- Only on systems over 10 kW
- On DC circuits of PV systems operating at greater than 80V where the circuit runs through a building (Correct answer)
- On all AC output circuits from the inverter
- Never required in PV systems
Correct answer: On DC circuits of PV systems operating at greater than 80V where the circuit runs through a building
NEC 690.11 requires AFCI protection on PV DC circuits operating above 80V when those circuits run through or inside a building structure.
NABCEP Installation & Safety 2
What is the minimum working space clearance required in front of electrical equipment rated 0-150V to ground per NEC 110.26?