Older doll houses were made for children to play in, and electricity was a component that was deemed unnecessary. The modern world often encourages competition, so adding electric wiring to doll houses has now become a part of the expectations of many hobbyists. Each room can be wired separately, or the entire house might be on one switch. Turning lights on and off shows how the imaginary people inhabiting the home live their lives.
Miniature lights have been available for many decades, but placing them in doll houses only became fashionable a few years ago. There are now hobby and craft shops that provide stylish table lamps for those who want even more realism in their doll house, and overhead lights come in many different shapes. For those who want appliances that seem to turn on and off, lights can be installed to help create the look of working models.