1. The mitzvah of kindling Chanukkah lights is fulfilled at the moment of kindling. Therefore, by that time the lights must be in their proper place (i.e., not above 20 amosand the like) and must contain enough oil to last at least a half-hour [after nightfall]. But if they were not in their proper place at the time of lighting and one moved them into position only after kindling them, or he added the necessary oil only after the kindling, then he must re-kindle them properly, but without reciting the blessings (Shulchan Aruch 675:2).
2. If he kindled the lights in a place where there is a strong wind and they are certain to blow out – even though they have not yet gone out – he has not fulfilled the mitzvah, and he is required to re-light them, but without the blessings. However, if he kindled them properly but they went out unexpectedly, he has fulfilled the mitzvah [and is not required to re-light them]. Nevertheless, the custom is to re-light them anyway [without the blessings] (Shulchan Aruch, 673 and 680;Kitzur Shulchan Aruch, 139).
