We light our storage areas with low cost efficient commercial fluorescent light fixtures that mount tight against the ceiling and are covered with polycarbonate covers to effectively eliminate UV radiation. We light the spaces well so that we can easily find and safely handle stored artifacts. Since the lights are off for and average of probably 23 hours a day, exhibit light preservation standards of 15-20fc for painted artifacts and 5fc for textiles and works of art on paper really do not apply. Instead, we turn to total exposure per year guidelines and stay way under those limits.
That being said, one must then ensure that they do not place a workspace in the storage areas and turn the lights on for several hours a day to light up a few tables for staff or volunteers to work at, or if they do to light those tables with task lights. In other words, use common sense and don’t work in storage areas for extended periods of time.