1. What is an Electrical Panel Size Calculator?

Definition: This calculator determines the required electrical panel size in amps based on the total volt-amperes (VA) and system voltage.

Purpose: It helps electricians and engineers properly size electrical panels for residential, commercial, and industrial applications.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• Panel Amps — Required panel size in amperes
• Total VA — Sum of all connected loads in volt-amperes
• Voltage — System voltage (typically 120V, 208V, 240V, or 480V)

Explanation: The total load in volt-amperes is divided by the system voltage to determine the current in amperes.

3. Importance of Proper Panel Sizing

Details: Correct panel sizing ensures safe operation, prevents overheating, and meets electrical code requirements while allowing for future expansion.

4. Using the Calculator

Tips: Enter the total VA (sum of all connected loads) and system voltage (default 120V). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between VA and watts?
A: VA is apparent power (volts × amps), while watts is real power. For resistive loads they're equal, but differ for reactive loads.

Q2: What's a typical residential panel size?
A: Most modern homes use 200A panels, though older homes may have 100A or 60A panels.

Q3: Should I add a safety factor?
A: Yes, the National Electrical Code requires adding 25% for continuous loads (over 3 hours).

Q4: How do I find the total VA?
A: Sum the VA ratings of all connected loads or multiply wattage by 1.25 for reactive loads.

Q5: What voltage should I use?
A: Residential typically uses 120V or 240V, commercial 208V or 480V, depending on your system.