Hilchos Pesach – 4 / searching for chametz

1. The obligation to search for chametz (leavened food) applies not only to locations where one regularly brings chametz but also to where it is only occasionally used (Shulchan Aruch and Mishnah Berurah 431).

2. The reason why we search for chametzat night is because that is when the light of a candle illuminates most brightly whereas during the day, when candle-light is inefficient, it would be impossible to check in the holes and crevices]. Another reason is that it is the time when most people are at home (ibid.).