If Shabbat candles look as if they are about to fall what may one do?
You could take a tray and put on it a loaf of bread or some other food and place the tray next to the falling candle. In that way if the light falls on the tray, the tray can be removed . You shold not directly extinguish the light unless there is a great danger which cannot be averted. The possibility of the use of a gentile should be considered. If you will relate to me the exact circustances of the situation I shall try to be more specific in my answer. esw