619. Making Use of Shabbos Oil

Shabbos 5:12

One may not place a vessel with a hole in the bottom that is filled with oil above the opening of a Shabbos lamp so that the oil will drip in. Similarly, one may not fill a bowl with oil and place it next to a lamp with the end of the wick in the bowl in order to draw its oil. These are prohibited as a preventive measure against the possibility of removing the oil in the vessel, which has not become disgusting by being in the lamp. If one affixed a container of oil to the lamp with cement, clay, or some other adhesive, it is permitted. One may not derive benefit on Shabbos from oil that was used for lighting. This is so even if the lamp gets extinguished or the oil drips out of it. The reason is because the oil was designated for an act of labor and is therefore muktzeh on Shabbos, which may not be handled.

Shabbos 5:13

One may not position a vessel under a lamp to catch dripping oil because doing so negates the ability to use that vessel on Shabbos. However, if one placed the vessel before Shabbos, it is permitted. One may position a vessel under a lamp on Shabbos to catch sparks because they have no substance and therefore do not negate the ability use the vessel. One may not, however, put water in such a vessel – not even before Shabbos – because this will cause the sparks to be extinguished quicker.