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TECHNICLIGHTLighting Systems

Circuit Load Calculator

Engineer

Calculate circuit current from total fixture wattage, see breaker utilization and the maximum number of fixtures a circuit can carry.

W

Voltage

Phase

Breaker Rating
If the driver's power factor isn't specified, 0.9 is a common default.
Circuit Current
9.66 A
Utilization
75.5%
Max Continuous Current (80%)
12.8 A

Within limit

Fixture Count Calculation

W

This circuit can carry up to 66 fixtures.

The total power on a lighting circuit must not exceed what its breaker can safely carry. This tool calculates circuit current with I=P/(V·PF) for single phase or I=P/(√3·V·PF) for three phase, then shows utilization against the commonly used "80% rule" for continuous loads (80% of the breaker's rated current). You can also enter the wattage per fixture to see how many fixtures a circuit can carry. The 80% figure and breaker selection should ultimately follow your local electrical code.