DIN EN 1838

DIN EN 1838 is a European standard for the emergency lighting of applied lighting technology, which replaced the only nationally applicable standard in July 1999. The most important requirements according to DIN EN 1838 and the technical rules for workplaces ASR A3.4/3 are the following: 

• Uniformity: The ratio of the highest to the lowest illuminance may be a maximum of 40 to 1.
• After the general lighting fails, the safety lighting must have reached 100% light output within 15 seconds.
• There must be at least 1 LUX horizontal illuminance on the center axis of the escape and emergency route.
• There must be at least one color rendering index of RA 40 of the light sources. 

All other important information about DIN standards can be found on their website din.de.