1. What is Generator Sizing?

Generator sizing is the process of determining the appropriate power output (in watts) needed from a generator to safely power all connected electrical loads with some margin for safety and future expansion.

2. How Does the Calculator Work?

The calculator uses the generator sizing formula:

Where:

• \( P_{total} \) — Required generator size in watts
• \( \Sigma P_{loads} \) — Sum of all connected electrical loads in watts
• \( 1.2 \text{ to } 1.5 \) — Safety factor accounting for startup surges and future expansion

Explanation: The safety factor accounts for motor startup currents (which can be 3-7 times running current) and provides headroom for additional loads.

3. Importance of Proper Generator Sizing

Details: Proper generator sizing ensures reliable operation, prevents overload conditions, improves fuel efficiency, and extends equipment life. Undersized generators can fail to start motors or overheat, while oversized generators operate inefficiently.

4. Using the Calculator

Tips:

1. Calculate or measure the total wattage of all devices to be powered simultaneously
2. Select an appropriate safety factor based on your usage:
   • 1.2 for mostly resistive loads (lights, heaters)
   • 1.35 for mixed resistive and motor loads
   • 1.5 for heavy motor loads or critical applications
3. The result shows the minimum generator size recommended

5. Frequently Asked Questions (FAQ)

Q1: Why is a safety factor needed?
A: Electrical motors require 3-7 times their running power during startup. The safety factor ensures the generator can handle these temporary surges.

Q2: Should I size for peak or running load?
A: The generator must handle the peak load (starting current for motors), which is why we apply the safety factor to the running load total.

Q3: How do I calculate total connected load?
A: Sum the wattage of all devices that might run simultaneously. Check nameplates or use: Watts = Volts × Amps × Power Factor (0.8 for motors).

Q4: What about three-phase equipment?
A: For three-phase, use: Watts = Volts × Amps × 1.732 × Power Factor. This calculator's result would be per phase.

Q5: Should I consider future expansion?
A: Yes, it's recommended to add 20-25% beyond your current needs if you anticipate adding more equipment later.