Dear Rabbi Simon,
We have begun to use a hotplate (food warmer, sometimes known by its Hebrew name platta) for hot food on Shabbat. Can you please advise how to use it in a halakhically acceptable way. Also using it with an electric time switch (colloquially know as a Shabbos clock).
Thanks
Philip
Dear Phil
Classically, a Shabbat hotplate is used for keeping cooked food hot on Shabbat. That is, hot food is placed on the platta before Shabbat where it stays hot until served.
According to some authorities, solid (as opposed to liquid) food which is already fully cooked may be placed on the platta on Shabbat itself, ie even if removed from the refrigerator on Shabbat morning. To clarify, cholent is generally regarded as a liquid-type rather than solid-type food. Therefore it must be kept on the hotplate overnight.
Note that this is not allowed in the case of an actual flame (or electric ring), which is used for cooking. The distinction: A hotplate is designed for keeping cooked food warm rather than cooking it in the first place. Therefore re-warming cooked food on a platta is allowed (according to these authorities).
Use of a time switch (popularly known as a Shabbos clock): Food which may not be placed on the hotplate on Shabbat (such as liquid or even more so food which has not already been fully cooked) should also not be placed there even if the time switch has not yet turned on the appliance, ie it is presently cold. However, you may utilise a Shabbos clock to turn (or leave) the hotplate off overnight, for example, and turn it on in the morning, in order to warm kugel, for example. This will save the needless use of electricity overnight. (However, note that this may not be recommended, for reasons of microbes, if there is food left on the platta during the time when it is switched off.)
I hope this is helpful.
Best wishes and bon appetite
Rabbi Rashi Simon