Lamp Efficacy Law and Legal Definition
According to 16 CFR 305.2 [Title 16 Commercial Practices; Chapter I Federal Trade Commission Subchapter C Regulations under Specific Acts of Congress; Part 305 Rule Concerning Disclosures Regarding Energy Consumption and Water Use of Certain Home Appliances and Other Products Required Under the Energy Policy and Conservation Act ("Appliance Labeling Rule")], lamp efficacy means "the light output of a lamp divided by its wattage, expressed in lumens per watt (LPW)."
