I thought this might be in the OSHA book and they do make a lot of references to "10 foot candles" around the other articles but in the electrical panel article they use the same language as NEC 110.26.
The Florida Building Code says
1205.3 Artificial light. Artificial light shall be provided that is adequate to provide an average illumination of 10 foot-candles (107 lux) over the area of the room at a height of 30 inches (762 mm) above the floor level.
That is based on ICC codes