In the context of lighting, nominal watts is the power rating of lamps as specified by the manufacturers. It represents the maximum power output that a lamp is designed to provide. However, the actual input power of a lamp can vary depending on the ballast used and includes the power consumed by the ballast, also known as ballast loss. The nominal wattage is a crucial specification for lamps as it helps users understand the expected performance and energy consumption of the lighting product. It serves as a reference point for comparing different lamps and selecting the appropriate one for specific lighting applications.