Circuit Load Calculator
Calculate total current draw and prevent circuit overloading. Determine how many devices you can safely add to any circuit. Professional tool for electricians following NEC guidelines and safety standards.
Why Use Our Circuit Load Calculator?
Prevent Overloading
Calculate exact current draw to prevent dangerous circuit overloads and breaker trips
NEC Compliance
Follows 80% continuous load rule and NEC requirements for safe electrical installations
Professional Tool
Used by electricians for load calculations, circuit planning, and electrical inspections
Common Circuit Configurations
Residential Circuits
NEC 80% Rule
Circuit Load Calculator
Add devices to calculate total circuit load and current draw
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Common Device Power Ratings
Typical power consumption of common electrical devices for load calculations
Lighting
Appliances & Outlets
Kitchen Appliances
HVAC & Large Loads
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Circuit Load Fundamentals
The 80% Rule (NEC 210.19)
The National Electrical Code requires that continuous loads (operating for 3+ hours) be limited to 80% of the circuit breaker rating. This safety factor prevents overheating and ensures reliable operation. For example, a 15A breaker should carry no more than 12A of continuous load (15A × 0.8 = 12A).
Continuous vs Non-Continuous Loads
Continuous loads operate for 3 hours or more (lighting, motors, heaters) and must follow the 80% rule. Non-continuous loads operate for less than 3 hours (vacuum cleaners, power tools) and can use the full circuit capacity. Mixed circuits require careful calculation of both load types.
Load Calculations for Lighting Circuits
For general lighting circuits, NEC allows a maximum of 12 outlets on a 15A circuit or 16 outlets on a 20A circuit when using the general lighting load of 1.5A per outlet. However, actual device wattages may allow more or fewer devices depending on their power consumption.
Demand Factors and Diversity
In practice, not all devices operate simultaneously, allowing for demand factors in load calculations. The NEC provides demand factors for different load types. However, for individual circuit calculations, it's safest to assume all connected loads will operate simultaneously unless specific usage patterns are known.
Electrical Safety Notice
This calculator provides load calculations for planning purposes. Actual electrical installations must comply with local electrical codes and be performed by licensed electricians. Always consider motor starting currents, temperature derating, and other factors that affect circuit capacity. Overloaded circuits can cause fires and electrical hazards.
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