If memory serves me right, this store occupied an entire block of downtown Chicago. You had 5 retail floors, 4 floors of offices, and two basement levels. The basic design was of three separate buildings, later connected.
In other words, there is no way this was the main panel for the entire place!
Indeed, considering the location, it is very possible that the place was once wired for DC, rather then AC. There may even be a building or two down there that are STILL DC!
