1. What is an Electrical Load Calculator?

Definition: This calculator estimates the total electrical load for a building based on square footage and appliance loads per NEC (National Electrical Code) standards.

Purpose: Helps electricians and builders determine the electrical service size needed for residential buildings.

2. How Does the Calculator Work?

The calculator uses the NEC formula:

Where:

• \( L \) — Total load (volt-amperes)
• \( S \) — Square footage of the dwelling
• 3000 VA — Small appliance load (two 20A circuits)
• 1500 VA — Laundry circuit load
• \( A \) — Fixed appliance loads (sum of nameplate ratings)

Explanation: The formula calculates general lighting load at 3VA/sq ft plus mandatory circuit requirements and appliance loads.

3. Importance of Load Calculation

Details: Proper load calculation ensures safe electrical system design, prevents overloads, and meets code requirements for service sizing.

4. Using the Calculator

Tips: Enter the building's square footage and sum of all fixed appliance nameplate ratings (water heater, HVAC, etc.). All values must be ≥ 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the 3VA/sq ft factor?
A: This is the NEC standard for general lighting load calculation in dwelling units.

Q2: Are there additional loads not included?
A: Yes, electric vehicle chargers, pools, or other special loads require separate calculations.

Q3: How do I find appliance loads?
A: Check nameplate ratings on appliances or manufacturer specifications (typically in watts or VA).

Q4: Is this for residential only?
A: Yes, commercial buildings use different calculation methods per NEC Article 220.

Q5: What about demand factors?
A: This calculator shows total connected load. Service size may be smaller after applying NEC demand factors.