An uninterruptible power supply comprises a power source (250) and a housing (110) to contain the power source. The housing comprises an outer surface (111) in which are located a recess (121) and a flat region (231). An electrical outlet (241) is located at the flat region, and a light source (130) is removably housed in the recess. The power source is capable of supplying electric power to the electrical outlet in response to a condition external to the uninterruptible power supply.