Lighting Systems Flashcards

Which lamp type produces light through an electrical discharge in a gas-filled tube without a filament, making it suitable for cold storage facilities?

Answer: Fluorescent

Fluorescent lamps use electrical discharge through mercury vapor and phosphor coating, though performance can decrease in very cold temperatures.

In a lighting retrofit economic analysis, simple payback period is calculated as:

Answer: Installation cost ÷ annual energy savings

Simple payback = Initial cost / Annual savings, giving the number of years to recover the investment.

What is the primary advantage of occupancy sensors in private offices compared to open-plan areas?

Answer: Greater energy savings due to predictable single-occupant patterns

Private offices have predictable vacancy periods, allowing occupancy sensors to turn lights off completely when the occupant is absent, yielding larger savings.

Ballast factor (BF) greater than 1.0 for a fluorescent ballast indicates:

Answer: The ballast drives the lamp above rated lumen output

A BF > 1.0 means the ballast drives the lamp to produce more lumens than the rated (reference ballast) value.

A parking garage uses 175W HID fixtures running 4,000 hours/year at $0.12/kWh. Replacing with 60W LED fixtures saves how much annually per fixture?

Answer: $55.20

Savings = (175-60)W × 4,000h / 1,000 × $0.12 = 115 × 4 × 0.12 = $55.20 per fixture annually.

Which IES illuminance category is typically recommended for fine detail assembly tasks requiring high visual acuity?

Answer: Category E (50–100 fc)

IES Category E (50–100 fc) is specified for tasks with fine details where visual performance is critical.

Power factor correction in lighting systems is important because:

Answer: It reduces reactive power demand and utility penalties

Correcting power factor minimizes reactive (non-working) power, reducing utility demand charges and distribution losses.