Technical Measurements Flashcards

7 cards from real BOC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Technical Measurements flashcards as text

A 120-volt circuit feeds a 10-ohm resistive heater. How much current does it draw?
Answer: 12 A
Ohm's law: I = V ÷ R = 120 ÷ 10 = 12 A.
What is the apparent power of a balanced three-phase load at 480 V and 100 A?
Answer: 83.1 kVA
Three-phase kVA = V × I × 1.732 ÷ 1,000 = 480 × 100 × 1.732 ÷ 1,000 ≈ 83.1 kVA.
A 10 kW electric heater runs for 8 hours. How much energy does it consume?
Answer: 80 kWh
Energy = power × time = 10 kW × 8 h = 80 kWh.
On most commercial electric bills, the demand charge is based on what?
Answer: The highest average kW over a short interval, often 15 minutes
Demand charges are set by peak kW averaged over a demand interval, commonly 15 or 30 minutes.
How many Btu are in one therm of natural gas?
Answer: 100,000 Btu
One therm equals 100,000 Btu.
A light meter reads illuminance in footcandles. One footcandle is approximately equal to how many lux?
Answer: 10.76 lux
One footcandle is one lumen per square foot, or about 10.76 lux.
A space temperature sensor reads 20°C. What is this in Fahrenheit?
Answer: 68°F
°F = (°C × 9/5) + 32 = 36 + 32 = 68°F.