Lighting circuit load calculator

⚡ Electrical Load Analysis

Circuit Load Calculator

Calculate how many lighting fixtures fit safely on a branch circuit. Checks NEC 80% continuous load rule, shows remaining capacity, and tells you exactly how many more fixtures you can add.

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NEC 210.19(A) — Continuous Load Rule: Lighting is classified as a continuous load (operating 3+ hours). Branch circuits must not exceed 80% of rated ampacity for continuous loads. A 20A breaker has a continuous limit of 16A.
Quick setup
Breaker Size (A)
Circuit Voltage (V)
Load Type
Lighting is always continuous per NEC
Quick add fixture
Fixtures on this circuit
2 fixtures
Fixture name
Type / preset
Watts each
Qty
Total W
—%
Circuit capacity usedof continuous limit
—
80% limit
0%20%40%60%80%100%
Total Wattage
—
watts
Total Amperage
—
amps drawn
Remaining Capacity
—
watts available
Breaker Status
—
—
NEC 80% continuous load rule — your circuit
Breaker rated capacity
—
Maximum theoretical
Continuous load limit (80%)
—
NEC 210.19(A) maximum
—
Load breakdown by fixture
FixtureQtyEachTotal% of circuit
How many more fixtures can you add?
Based on your remaining circuit capacity:
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The calculators and tools on LightingCalc.lighting are provided for general guidance and informational purposes only. Results are estimates based on standard formulas and the values you enter — they do not constitute professional engineering, electrical, or architectural advice. Always verify calculations with a qualified professional before making decisions for any safety-critical, code-compliance, or commercial application. LightingCalc.lighting makes no representations or warranties as to the accuracy or completeness of any result, and accepts no liability for errors, omissions, or any outcomes arising from reliance on this information.