Q. Shalom, Dear Rabbi, What is the reason that the Hanukkah candles have to be lit for at least half an hour? What is so special about a thirty-minute period?
Thanks.

A. The Talmud (Shabbos 21b) mentions that the menorah lights must burn until the time the Tarmudoi have departed from the streets. Rashi (ibid.) explains that; they were a nation of street peddlers who sold lighting materials, and waited in the streets later than the general populace, as their wares might be then needed.

Indeed the half an hour period is not cited in the Talmud. Horav Shlomo Miller Shlit’a told us that the RI”F commentary might be the first one to mention that time period. The Rosh, Tur and Bais Yosef (O.H. 672) as well as the Rambam (Chanuka 4: 5) and Shulchan Aruch (ibid.) also record it. They must have assessed that to be the period required by the Talmud. It is noteworthy that they mention “K’mo Chatzi Shaah” or approximately a half an hour.

A time period of a half an hour is used in several instances in Halacha, such as the time for beginning praying mincha after mid-day (Talmud Yuma 28b), or eating before tefilah or separating between milk and meat etc.

Rabbi A. Bartfeld as advised by Horav Shlomo Miller Shlit”a