Electric / By DaviD Hickey //////////////////////////////////////////////////////////////////////////////////////////////////// Leave the L ghts On A business doesnâ€™t invest in a sign so it can only be seen during the day. A business wants a sign that can be bright enough so that customers can easily find their location when itâ€™s dark outside. In fact, effective illumination is one of the key elements of sign visibility, along with size, sign angle, location, and contrast. 48 Sign Builder Illustrated // September 2013 Unfortunately there are efforts afoot by interest groups and government officials to limit the ability of businesses to advertise at night. For example, the International Dark-Sky Association (IDA) exists to restrict the use of nighttime outdoor lighting. IDA wants outdoor lighting fixtures to signshop.com photo: creative sign designs / tampa, fl A look into both sides of the debate on sign lighting.