Question 1

How do I calculate power consumption cost?

Accepted Answer

Cost = Power (kW) × Time (hours) × Rate ($/kWh). A 1500W heater for 8 hours at /bin/zsh.12/kWh: 1.5 × 8 × 0.12 = .44 per day.

Question 2

What is the difference between watts and watt-hours?

Accepted Answer

Watts = power (rate of energy use). Watt-hours = energy consumed over time. A 100W bulb for 10 hours = 1000 Wh = 1 kWh. Your electric bill charges for kWh, not watts.

Question 3

What's the difference between mechanical and electrical horsepower?

Accepted Answer

Mechanical HP (550 ft·lb/s) = 745.7W. Electrical HP = 746W. Metric HP (PS) = 735.5W. Boiler HP = 9810W. Different industries defined their own standards.

Question 4

How do I size a motor or generator?

Accepted Answer

Calculate peak power needs, add 20-25% safety margin. Consider duty cycle - continuous vs intermittent use affects sizing differently.

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