An illuminated exit sign is designed to be permanently fixed in place to identify an exit.
Current standards for illuminated exit signs were adopted by Congress in in EPAct 2005 and went into effect in 2006. The standards require maximum energy use of 5 Watts (W) per face (e.g. 5 W for a one direction sign, 10 W for a sign that faces two different directions).
California first adopted state standards for exit signs in 2002, effective in 2003. Eight additional states (AZ, CT, MD, NJ, NY, OR, RI, WA) adopted the CA standards, though all standards but those in Maryland were preempted by the national standards before taking effect.
Illuminated exit signs are required by safety codes in commercial buildings. There are millions of these signs in place in buildings across the US in continuous operation. Manufacturers can utilize light-emitting diode technology (LED) to meet the standard.