NABCEP Safety Practices 5 — Questions and Answers
Question 1: An installer is stringing wire through conduit on a rooftop and feels resistance. A co-worker suggests using a lubricant. Which lubricant is safe to use with PV wiring in conduit?
- Petroleum-based grease
- UL-listed wire-pulling lubricant compatible with conductor insulation (Correct answer)
- WD-40 spray
- Motor oil
Correct answer: UL-listed wire-pulling lubricant compatible with conductor insulation
Only UL-listed wire-pulling lubricants compatible with the conductor insulation type should be used; petroleum-based products can degrade certain insulation materials.
Question 2: Which condition requires a solar installer to immediately stop work and evacuate the roof?
- Cloud cover reduces irradiance below 200 W/m²
- Lightning is visible or thunder is heard within 30 miles (Correct answer)
- Ambient temperature drops below 40°F
- Wind speed exceeds 10 mph
Correct answer: Lightning is visible or thunder is heard within 30 miles
The 30-30 rule dictates that if thunder is heard or lightning is seen within 30 miles, work should stop and workers should seek shelter for at least 30 minutes after the last strike.
Question 3: A PV installer is asked to use a scissor lift to install racking on a carport structure. At what wind speed should work from the elevated platform cease?
- 15 mph
- 25 mph
- 35 mph
- The manufacturer's rated maximum, typically 28–35 mph (Correct answer)
Correct answer: The manufacturer's rated maximum, typically 28–35 mph
Aerial work platforms must be operated within manufacturer-specified wind speed limits, which are typically listed in the operator's manual and commonly range from 28–35 mph.
Question 4: What information must appear on a lockout/tagout tag to meet OSHA 29 CFR 1910.147 requirements?
- Only the date the lock was applied
- The authorized employee's name, reason for lockout, and date (Correct answer)
- The equipment serial number and voltage rating
- The supervisor's name and work order number
Correct answer: The authorized employee's name, reason for lockout, and date
OSHA LOTO tags must identify the authorized employee who applied them, the reason for the lockout, and the date to ensure accountability and safe removal.
Question 5: During a site safety audit, an inspector finds workers not wearing hard hats while working below other crew members on a two-story commercial installation. Which OSHA standard is being violated?
- 29 CFR 1926.100 — Head Protection (Correct answer)
- 29 CFR 1926.502 — Fall Protection
- 29 CFR 1910.135 — Head Protection General Industry
- 29 CFR 1926.416 — Electrical Safety
Correct answer: 29 CFR 1926.100 — Head Protection
OSHA 29 CFR 1926.100 requires hard hats in construction areas where there is a risk of head injury from falling objects.
Question 6: A technician measures an unexpected voltage of 85V DC between the negative PV conductor and the equipment grounding conductor. What does this most likely indicate?
- Normal operating voltage from string capacitance
- A ground fault in the PV array (Correct answer)
- The inverter is operating in low-irradiance mode
- The grounding conductor is undersized
Correct answer: A ground fault in the PV array
Voltage between a PV conductor and the equipment grounding conductor indicates a ground fault, which must be investigated and cleared before further work.
Question 7: When disposing of a damaged lithium-ion battery from a solar-plus-storage system, what special handling is required beyond normal electrical waste disposal?
- No special handling; treat as standard e-waste
- Transport in a non-conductive sealed container, keep terminals covered, and follow carrier hazmat rules (UN3480) (Correct answer)
- Discharge completely with a load resistor, then discard in regular trash
- Puncture the cells to release pressure before shipping
Correct answer: Transport in a non-conductive sealed container, keep terminals covered, and follow carrier hazmat rules (UN3480)
Damaged lithium-ion batteries are classified as hazardous materials (UN3480) and must be shipped in appropriate non-conductive containers with terminal protection per DOT/IATA regulations.
NABCEP Safety Practices 5
An installer is stringing wire through conduit on a rooftop and feels resistance.
A co-worker suggests using a lubricant.
Which lubricant is safe to use with PV wiring in conduit?