608. Lighting a Fire Before Shabbos

Shabbos 3:18

We may not place bread in an oven shortly before Shabbos, nor may we place a cake on the coals unless there is enough time for the surface stuck to the wall of the oven (as their ovens were) or the side facing the fire to form a crust. If this is in fact the case, one may leave the bread or cake to continue baking because if one were to stoke the coals, it would ruin the baking. If bread were placed in the oven with insufficient time for the crust to form before Shabbos, if he intended to violate the rules, it is forbidden to eat the bread until after Shabbos, leaving enough time that it could have been baked then. If one did so unintentionally, it is permitted to remove bread for the three Shabbos meals. When removing the bread, one may not use the specialized baking tools that one would normally use for this task on weekdays. Rather, one should use a knife or another basic kitchen utensil.

Shabbos 3:19

One may kindle a fire before Shabbos from any substance he wishes, either on the ground or in a torch. He may then use its light to see and its heat to warm himself on Shabbos. He must, however, get the majority of the fire to light before Shabbos such that the flame rises on its own. If he didn’t get the majority of the fire lit, he may not benefit from it on Shabbos out of concern that he may stoke the wood to get the flame to rise. If he uses a single log as fuel, he must get the majority of its thickness and the majority of its circumference lit before Shabbos starts.