1. What is the Generator Sizing Formula?

The generator sizing formula calculates the minimum generator capacity needed to power all connected loads in your home, with an additional safety margin to account for startup surges and future expansion.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( P_{total} \) — Required generator size (watts)
• \( \Sigma P_{loads} \) — Sum of all connected loads (watts)
• \( 1.2 \text{ to } 1.5 \) — Safety factor (20% to 50% margin)

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

3. Importance of Proper Generator Sizing

Details: Correct generator sizing ensures reliable operation of all essential equipment while preventing damage from overload conditions. Undersized generators may fail to start motors or overheat, while oversized units are less efficient and more costly.

4. Using the Calculator

Tips:

1. Calculate or measure the total wattage of all devices you plan to power simultaneously
2. Select a safety factor based on your needs (1.2 for minimal margin, 1.5 for heavy motor loads)
3. The result shows the minimum generator capacity required in watts and kilowatts

5. Frequently Asked Questions (FAQ)

Q1: What's included in "connected loads"?
A: Sum the running watts of all appliances, lights, and devices you want to power simultaneously during an outage.

Q2: Why different safety factors?
A: 1.2 for resistive loads (lights, heaters), 1.35 for mixed loads, 1.5 for homes with many motor-driven appliances (AC, refrigerators, pumps).

Q3: Should I consider startup currents?
A: Yes, the safety factor accounts for this. For large motors, add their starting watts separately.

Q4: What about future expansion?
A: Choose a higher safety factor (1.5) if you anticipate adding more electrical loads later.

Q5: How do I convert watts to generator size?
A: Generator capacities are typically rated in watts (W) or kilowatts (kW). 1000W = 1kW.