For transilluminated displays, such as lighted alarm tiles, the luminance of the dim state (if used) should be at least 10 percent greater than the inactivated state; the brightest state should not be more than 300 percent of the surrounding luminance.
Additional Information:
Transilluminated displays should have no more than 3 levels. Brightness of 'on' alarms should not be annoying or distracting.