NABCEP Safety Practices 2 — Questions and Answers
Question 1: When working on a rooftop PV installation, what is the minimum approach boundary for unqualified workers near exposed energized conductors operating above 50V?
- 1 foot
- 3 feet 6 inches (Correct answer)
- 6 feet
- 10 feet
Correct answer: 3 feet 6 inches
NFPA 70E defines the limited approach boundary for unqualified workers as 3 feet 6 inches for voltages between 50V and 750V.
Question 2: A solar installer notices the roof decking is wet after rain. What is the correct safety action before resuming rooftop work?
- Continue working with extra caution
- Wait until surfaces dry and re-inspect footing hazards (Correct answer)
- Apply sand or grip tape immediately and continue
- Wear rubber-soled boots and proceed
Correct answer: Wait until surfaces dry and re-inspect footing hazards
Wet surfaces create fall hazards; workers must wait for surfaces to dry and confirm safe footing conditions before resuming work.
Question 3: Which document establishes the lockout/tagout (LOTO) procedures that solar installers must follow when servicing PV systems?
- OSHA 29 CFR 1926.50
- OSHA 29 CFR 1910.147 (Correct answer)
- NEC Article 690
- IEEE 1547
Correct answer: OSHA 29 CFR 1910.147
OSHA 29 CFR 1910.147 is the Control of Hazardous Energy (Lockout/Tagout) standard applicable to servicing electrical equipment.
Question 4: What type of fire extinguisher is appropriate for use on a live PV electrical fire?
- Class A (water-based)
- Class B (CO2 or dry chemical)
- Class C (CO2 or dry chemical) (Correct answer)
- Class D (dry powder)
Correct answer: Class C (CO2 or dry chemical)
Class C extinguishers use non-conductive agents (CO2 or dry chemical) and are rated for energized electrical equipment fires.
Question 5: During a PV system commissioning, a worker must verify the string open-circuit voltage. Which PPE is required for this measurement?
- Safety glasses only
- Leather gloves rated for the voltage
- Rubber insulating gloves rated for the voltage with leather protectors and safety glasses (Correct answer)
- Hard hat and high-visibility vest only
Correct answer: Rubber insulating gloves rated for the voltage with leather protectors and safety glasses
Electrical measurements on energized PV conductors require rubber insulating gloves rated for the system voltage, leather protectors, and eye protection per NFPA 70E.
Question 6: What is the primary purpose of a PV system's rapid shutdown (RSD) requirement under NEC 690.12?
- To reduce equipment costs during installation
- To limit conductors in the array boundary to safe voltages for first responders (Correct answer)
- To improve system efficiency during grid outages
- To protect inverters from overvoltage conditions
Correct answer: To limit conductors in the array boundary to safe voltages for first responders
NEC 690.12 rapid shutdown is designed to de-energize PV conductors within the array boundary to a safe voltage within 30 seconds of activation, protecting first responders.
Question 7: A NABCEP-certified installer discovers a roof penetration that was not properly flashed during a prior installation. What is the correct course of action?
- Seal it with roofing caulk and continue
- Document the deficiency and notify the responsible party before covering it (Correct answer)
- Cover it with a panel and note it in the O&M manual
- Ignore it if the leak has not appeared yet
Correct answer: Document the deficiency and notify the responsible party before covering it
Proper professional practice requires documenting pre-existing deficiencies and notifying responsible parties before proceeding to avoid liability and ensure building integrity.
NABCEP Safety Practices 2
When working on a rooftop PV installation, what is the minimum approach boundary for unqualified workers near exposed energized conductors operating above 50V?