Q. What is the reason and the source for the tradition kept by some to light candles at the simchas beis hashoeva?

A. Kaf Hachaim (643: 9) quotes the tradition of lighting candles at the simchas beis hashoeva and explains that they are lit in honor of the seven Holy Ushpizin that guide the Yom Tov, and therefore we light that number. See also Nitei Gavriel (72: 11).

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a