A non-Jew may perform melacha on Shabbos (or Yom Tov) if he is doing so for his own benefit (adatah d’nafshey), and the Jew merely has tangential benefit.  There are different ways of interpreting this leniency, which hinge on the crucial question of how to decide when the non-Jew is doing the melacha for himself rather than for the Jew.  Many years ago, in order to clarify the cRc position on this matter, Rabbi Eisenbach, under the direction of Rav Schwartz, instituted a very simple two-part rule about amirah l’akum at cRc events:

• Anything that a Jew is not allowed to do on Shabbos, a non-Jew may not do.
• Anything that a Jew is permitted to do on Shabbos, a non-Jew may do in any manner which the non-Jew chooses, because he is choosing to perform it via a melacha for his own benefit.

The following are some detailed examples of these rules, as they apply to a hotel situation.

• Anything that a Jew is not allowed to do on Shabbos, a non-Jew may not do.  The reason for this rule is that since the non-Jew is doing the act for the Jewish guests, it is difficult or impossible to justify the act as being done adatah d’nafshey – even if the non-Jew has some personal benefit from the melacha.

Convection oven – A Jew may not open a convection oven on Shabbos, because doing so causes the fan and flames to turn off.  Therefore, a non-Jew may not open the door of the convection oven, even though there are those who suggest that there are reasons why doing so might be considered adatah d’nafshey.¹

• Anything that a Jew is permitted to do on Shabbos, a non-Jew may do in any manner which he chooses.

Slicing meat – A Jew may slice meat by hand on Shabbos, and therefore a non-Jew assigned to slicing meat may choose to use the electric meat slicer to make the job easier for him.  One could question this because an electric slicer can produce slices that are thinner and more uniform than most people can create with a knife, which means that the non-Jew is using the slicer to benefit the Jewish hotel guests who will appreciate the nicer slices.  However, Rav Schwartz disagrees with this and holds that a professional chef is capable of cutting slices as precisely, or almost as precisely, as an electric knife; therefore, the non-Jew’s choice to use the electric knife is considered melechah done adatah d’nafshey.
Washing dishes – There exist ways in which a Jew may wash dishes on Shabbos; therefore, the non-Jewish kitchen staff may choose to use an automatic dishwasher to save themselves time or to satisfy the requirements of the (non-Jewish) Board of Health.
Cleaning floors – On Shabbos, Jews are permitted to clean the floor of a kitchen, ballroom or hallway by sweeping or by bending down and actually picking up the refuse left on the floor.  Since there is a way for cleaning to be done without violating any issur, the non-Jews are permitted to mop or vacuum, so as to make the cleaning easier for themselves and/or so that the floor’s appearance will be clean enough to satisfy their professional standards of cleanliness.  See below for an exception to this rule. 

Exceptions

• Shulchan Aruch² rules that a non-Jew may not do melacha adatah d’nafshey on a Jew’s property, because people who see him doing the melacha will think the Jew specifically told him to do it on Shabbos.  Therefore, mopping and other examples listed above as being permitted may only be performed in the recesses of the kitchen or in a locked ballroom, but not in the public areas of a hotel or in other areas where hotel guests may be present.  Similarly, waiters may not write down guests’ meal orders in the dining room, because people might think a guest specifically asked the waiter to write down the details of his order.³
• There are times when amirah l’akum is permitted even if it is not done adatah d’nafshey;⁴ some details of those halachos were discussed in Sappirim 10, and questions regarding these issues should be addressed by a moreh hora’ah.