Is it permissible to place a cold solid food on a hot plate (controlled by timer) which is switched off, but is due to come on a later time?
I also understand that Rav Moshe Feinstein was against the use a timer for anything other than lights. Is there any reason that one should be machmir and avoid using timers for hot plates?
1. This is permitted according to some Poskim, though some are careful to place another item (such as a fork or other utensil) between the hot plate and the food. Please see here for details.
2. There is no need to avoid the use of timers hot plates.
Although it is true that Rav Moshe was generally against the use of timers, even he permitted the matter for lights, which was the common custom.
Today it is the common custom to use timers for almost everything, and the case of a hot plate is not one of the more “severe” types of electrical appliance, since it makes no noise.