If one lit wax candles on the Shabbat table, and during the meal the candle got knocked over in a manner that does not pose a risk, is one allowed to lift the candle and put it back in place? Normally, of course, it is forbidden to move candles, as they are considered Mukseh. Can an exception be made in this case, when a candle fell on the table?
The Mishna Berura (Rav Yisrael Meir Kagan, 1839-1933), in Siman 277 (Se’if Katan 18), cites the Bah (Rav Yoel Sirkis, Poland, 1561-1640) as commenting that in such a case, if no minor or non-Jew is available to lift up the candle, one should shake the tablecloth to remove the candle. One is not permitted to lift the candle or to extinguish the flame, and thus his only option is to shake the candle off the table. The Mishna Berura adds, however, that nowadays, when people are very anxious when it comes to fire, we must be concerned that one might become frightened when shaking the candle off the table that the tablecloth or carpet will catch fire, and he will then extinguish the flame. Therefore, Halacha permits one to pick up the candle and put it back in a safe place, as otherwise it is likely that one would violate the more severe prohibition of extinguishing the fire.
The Mishna Berura also comments that if a napkin or some object on the table catches fire, and one would be very anxious leaving it in place, he may remove it and put it somewhere safe. He may not extinguish the fire, but he may remove the object. If the tablecloth or the table catches fire, one should put water around the perimeter of the flames so that when they spread, they will be extinguished. One may not extinguish the fire directly, but should instead place water around it. Some authorities ruled that one should not use water for this purpose, as putting water on the tablecloth would violate the Torah prohibition of laundering on Shabbat, but the Mishna Berura allows using water in such a case. One may also ask a gentile to extinguish the fire.
Needless to say, this entire discussion relates to situations where there is no danger to life. If something catches fire and creates a potentially life-threatening situation, then clearly it is permissible to do whatever is needed to put out the flames.
Summary: If a candle falls on the table on Shabbat in a manner that does not pose danger, one should ask a gentile or child to lift the candle and put it in back in place, and if there is no gentile or child, then one may lift it himself, even though candles generally may not be handled on Shabbat. If a napkin or other object catches fire, one should move it to a safe location. If the tablecloth or table catches fire, a gentile should be asked to extinguish the flame, and if no gentile is present, one may place water around the flames so they are extinguished as they spread. Of course, if a fire poses a potentially life-threatening situation it may be extinguished.