General purpose lighted exit signs mark exits and passages toward exits to guide people out of dry, nonhazardous locations such as schools, offices, and commercial buildings. They mount near exit route doors and doorways and hardwire into an electrical system that keeps them lit for visibility. Signs with battery backup switch to their battery during a power outage. Signs without battery backup are commonly used in buildings with emergency systems that supply power during an outage. All signs have universal arrow or chevron knockouts that can be set up at the point of installation to indicate the direction of travel to the nearest exit if the path is not immediately apparent. Local safety codes may require that lighted emergency exit signs be made of a specific material and have lettering and graphics of a specific color, size, and arrangement.