Electrical Load Calculator
Understanding Electrical Load Calculations
Continuous vs. Non-Continuous Loads
Continuous Load: A load where the maximum current is expected to continue for 3 hours or more. The NEC requires these loads to be calculated at 125% of their rated current.
Non-Continuous Load: A load where the maximum current is expected for less than 3 hours. These are calculated at 100% of their rated current.
Load Calculation Formula
Total VA = (Continuous Load × 1.25) + Non-Continuous Load Amperage = Total VA / VoltageCommon Appliance Wattages
- LED Light Bulb: 10-15W
- Refrigerator: 150-400W
- Microwave: 800-1200W
- Toaster: 800-1500W
- Electric Stove: 3000-8000W
- Central AC (3 ton): 3500W
- Electric Water Heater: 4500-5500W
- Clothes Dryer: 1800-5000W
- Dishwasher: 1200-1500W
- Washing Machine: 500-900W
About Electrical Load Calculator
Electrical Load Calculator - Calculate Total Electrical Load
Calculate total electrical load for your home, room, or project. Add appliances and fixtures to determine total wattage, amperage, and suggested breaker sizing.
How to Calculate Electrical Load
Electrical load calculation involves:
- List all loads: Identify every appliance, light, and outlet
- Classify loads: Determine if each is continuous (3+ hours) or non-continuous
- Calculate totals: Continuous loads × 125% + Non-continuous loads × 100%
- Convert to amperage: Total VA ÷ Voltage = Amperage
Continuous vs. Non-Continuous Loads
Continuous Loads: Operate for 3+ hours continuously. Examples include:
- General lighting circuits
- Office receptacles in commercial buildings
- Sign lighting
- HVAC systems (often continuous during extreme weather)
These must be calculated at 125% of their rated current (NEC 210.20(A)).
Non-Continuous Loads: Operate less than 3 hours. Examples include:
- Small appliances (kitchen counter outlets)
- Laundry appliances
- Bathroom exhaust fans
- Garbage disposals
Common Appliance Wattages
| Appliance | Typical Wattage | Voltage |
|---|---|---|
| LED Light Bulb | 10-15W | 120V |
| Ceiling Fan | 50-100W | 120V |
| Refrigerator | 150-400W | 120V |
| Microwave | 800-1200W | 120V |
| Toaster | 800-1500W | 120V |
| Dishwasher | 1200-1500W | 120V |
| Washing Machine | 500-900W | 120V |
| Clothes Dryer (Electric) | 3000-5000W | 240V |
| Central AC (3 Ton) | 3500W | 240V |
| Electric Water Heater | 4500-5500W | 240V |
| Electric Stove | 3000-8000W | 240V |
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