The scope of this paper includes dimmable fluorescent ballast and Light Emitting Diode (LED) drivers that are controlled by 0-10 V (1-10 V) control input. This paper explains the relationship between the control input voltage and overall energy consumed by these ballasts and drivers. Purpose Dimmable fluorescent ballasts and LED drivers consume less power when dimming. However@ determining the energy savings at different output levels can be challenging because several components comprise lighting systems: control@ control wiring@ power source@ and light source. This paper describes the signal path from the user control input through the control wiring@ ballast or driver@ and lamp or LED module. It also explains factors that affect energy consumption and savings@ efficacy@ and user experience at each stage. This paper is written for stakeholders interested in energy-efficient lighting@ including manufacturers@ specifiers@ facility managers@ and consultants.