One of the most common mistakes made in Non-Residential lighting compliance is in calculating the wattage for medium base incandescent lights (screw-in type fixtures). To calculate the wattage for medium base fixtures, two values need to be compared: (a) the total lamp wattage proposed for the fixture, and (b) 75 watts per fixture. The wattage used in the calculation of Actual Lighting Power must be the larger of these two values. (Standards Section 5.2.4-B.2)