Certified Energy Auditor Certification Lighting and Electrical Systems 5 — Questions and Answers
Question 1: Which lighting source type has the highest luminous efficacy available in commercial products as of current standards?
- High-pressure sodium (HPS)
- Ceramic metal halide (CMH)
- Linear fluorescent T5HO
- LED (Correct answer)
Correct answer: LED
Commercial LED luminaires routinely achieve 150–200+ lm/W system efficacy, surpassing all other available commercial lamp technologies.
Question 2: A facility operates at 480V three-phase. A voltage imbalance test shows Phase A = 478V, Phase B = 462V, Phase C = 482V. What is the approximate percent voltage imbalance?
- 0.9%
- 1.7%
- 2.6% (Correct answer)
- 3.4%
Correct answer: 2.6%
Average = (478+462+482)/3 = 474V; max deviation = 474−462 = 12V; imbalance = 12/474 × 100 ≈ 2.5%, closest to 2.6%.
Question 3: What is the purpose of a 'lighting power allowance' in ASHRAE 90.1's Building Area Method?
- To set the maximum allowable LPD for an entire building based on its primary use type (Correct answer)
- To calculate the minimum lumens required per square foot by occupancy
- To determine the peak demand credit for daylighting controls
- To establish the maintenance illuminance targets for each room type
Correct answer: To set the maximum allowable LPD for an entire building based on its primary use type
The Building Area Method assigns a single maximum W/ft² allowance to the whole building based on its primary classification (e.g., office, retail, warehouse).
Question 4: An auditor identifies induction motors running at 60% load as a major reactive power source. Which device placed near the motors would most efficiently correct the power factor locally?
- Voltage regulators
- Power factor correction capacitors (Correct answer)
- Isolation transformers
- Phase converters
Correct answer: Power factor correction capacitors
Capacitors installed at or near motor terminals supply reactive power locally, reducing reactive current in the upstream distribution system and improving facility power factor.
Question 5: What is the significance of the 'Useful Life' rating (L70) for LED luminaires in an energy audit?
- The hours at which the LED consumes 70% of its rated wattage
- The hours at which lumen output has depreciated to 70% of initial output (Correct answer)
- The hours at which color temperature shifts by 70 Kelvin
- The percentage of LEDs still operating at end of rated life
Correct answer: The hours at which lumen output has depreciated to 70% of initial output
L70 defines the operating hours at which a LED luminaire's light output has declined to 70% of its initial lumens, the industry standard threshold for end of useful life.
Question 6: Which type of photosensor control wiring is most susceptible to false triggering from electrical noise in industrial facilities?
- 0-10V analog (Correct answer)
- DALI digital
- Wireless Zigbee
- Dry contact relay
Correct answer: 0-10V analog
0-10V analog signals operate at low voltage levels and are vulnerable to EMI-induced voltage fluctuations that can falsely adjust dimming levels in electrically noisy environments.
Question 7: During an electrical audit, an auditor finds that a facility pays for 500 kVAR of reactive power monthly. Installing power factor correction equipment brings the power factor from 0.72 to 0.95. What is the primary financial benefit beyond avoiding reactive power charges?
- Reduced real energy consumption (kWh) in all equipment
- Reduced current draw, lowering conductor I²R losses and potentially reducing demand charges (Correct answer)
- Elimination of harmonic distortion fees
- Automatic compliance with ASHRAE 90.1 LPD limits
Correct answer: Reduced current draw, lowering conductor I²R losses and potentially reducing demand charges
Improving power factor reduces line current for the same real power, which decreases I²R resistive losses in conductors and may lower the peak kW demand measured by the utility.
Certified Energy Auditor Certification Lighting and Electrical Systems 5
Which lighting source type has the highest luminous efficacy available in commercial products as of current standards?