Emergency Lighting
            Emergency lighting switches on automatically when a 
building experiences a power outage. In addition to illuminated exit and
 emergency directional signs, products include automatic, standby, 
emergency, and auxiliary electric power equipment of all voltages that 
incorporate a charging means, a battery, and a switchover device to 
activate emergency and egress lighting when the power goes out.
Emergency
 lights and exit signs consist of a lighting source, a device to focus 
and intensify the light, a backup power supply, and a test function. The
 lights consist of clusters of high-intensity light-emitting diodes 
(LEDs). Battery backup ballasts may be installed to automatically switch
 into emergency mode. Modern fixtures may also include a small 
transformer that steps down the voltage from main current to the 
required low voltage.
Through NEMA, Members promote reasonable, 
repeatable, and unburdensome product test procedures and performance 
criteria that are required for regulatory bodies and certification labs.