Certified Energy Auditor Certification Certified Energy Auditor Lighting and Electrical Systems Questions and Answers 2 — Questions and Answers
Question 1: What is the primary advantage of using LED T8 retrofit tubes over magnetic ballast fluorescent T12 systems in commercial buildings?
- Higher color rendering index only
- Energy savings of 40-60% with longer lamp life (Correct answer)
- Increased heat output for space heating
- Compatibility with existing magnetic ballasts without modification
Correct answer: Energy savings of 40-60% with longer lamp life
LED T8 retrofits typically deliver 40-60% energy savings over T12 fluorescent systems while lasting 2-3 times longer.
Question 2: During an energy audit of an office building, you measure a power factor of 0.72 on the main electrical panel. What is the most likely consequence of this low power factor?
- Reduced lighting output across the facility
- Utility penalty charges and increased apparent power demand (Correct answer)
- Immediate risk of electrical fire
- Automatic shutdown of HVAC systems
Correct answer: Utility penalty charges and increased apparent power demand
A power factor below 0.85 typically triggers utility penalty charges because the facility draws more apparent power (kVA) than real power (kW).
Question 3: An energy auditor discovers that a warehouse uses 400W metal halide high-bay fixtures operating 16 hours per day. Which replacement strategy offers the greatest energy reduction?
- Replace with 250W metal halide fixtures
- Install 150W LED high-bay fixtures with occupancy sensors (Correct answer)
- Switch to 320W pulse-start metal halide lamps
- Add reflectors to existing fixtures
Correct answer: Install 150W LED high-bay fixtures with occupancy sensors
150W LED high-bays with occupancy sensors can reduce energy use by over 75% compared to 400W metal halide through both wattage reduction and controls.
Question 4: What does a demand response program typically require from a commercial building's electrical system during peak grid events?
- Switching all lighting to emergency battery backup
- Temporarily reducing electrical load by curtailing non-critical systems (Correct answer)
- Permanently disconnecting from the utility grid
- Increasing generator output to feed power back to the grid
Correct answer: Temporarily reducing electrical load by curtailing non-critical systems
Demand response programs ask participants to temporarily shed or curtail non-critical electrical loads during peak demand periods in exchange for financial incentives.
Question 5: When conducting a lighting audit, an energy auditor calculates that a space has 1.3 watts per square foot of installed lighting power density. According to ASHRAE 90.1 for a typical open office, what conclusion should the auditor draw?
- The space meets current energy code requirements
- The lighting power density exceeds the code maximum and represents a savings opportunity (Correct answer)
- The measurement indicates insufficient lighting for occupant comfort
- The space requires additional task lighting
Correct answer: The lighting power density exceeds the code maximum and represents a savings opportunity
ASHRAE 90.1 sets open office lighting power density allowances near 0.61-0.82 W/sq ft, so 1.3 W/sq ft significantly exceeds the standard.
Question 6: Which harmonic distortion issue is most commonly associated with large installations of electronic ballasts and LED drivers on a commercial electrical system?
- Increased voltage at the service entrance
- Third-order harmonics causing neutral conductor overheating (Correct answer)
- Reduced ground fault protection sensitivity
- Phase imbalance between utility feeders
Correct answer: Third-order harmonics causing neutral conductor overheating
Non-linear loads like electronic ballasts and LED drivers generate third-order harmonics that add in the neutral conductor, potentially causing dangerous overheating.
