The Laws of Shabbos part 6 vol.4, no.17
One generally may not request from or hire a gentile to perform an act which the Jew is prohibited from performing on Shabbos. However under certain circumstances a gentile hired worker may perform work for a Jew on Shabbos.
Jewish law distinguishes between two types of working agreements. A worker can be paid according to the time he works or according to the task he is hired to perform. A time based worker cannot work for a Jew on Shabbos. A worker hired to perform a task can perform the job even on Shabbos since the Jew did not specifically hire him to work on Shabbos and the gentile can really perform the work when he chooses.1
Examples of workers hired to perform a task include dry cleaners, tailors and mechanics. Therefore, one may drop off clothing at the dry cleaners before Shabbos even if the work will be performed on Shabbos. However he must allow enough time for the garment to be possibly cleaned either before or after Shabbos.2 He may not ask that the work be done on Shabbos. Therefore he may not drop off the clothing right before Shabbos and request that it should be ready right after Shabbos, since in this way he is in reality asking that the job be performed on Shabbos.
A contracted worker like a plumber or an electrician may not perform the work in the house of a Jew because of the halachic prohibition of maris ayin, that is, it would look like the Jew hired the gentile to perform work for him specifically on Shabbos.3
A gentile maid may perform her job on Shabbos 4 provided the following conditions are
fulfilled: she cannot be specifically told to do any prohibited acts, there will be
no prohibited benefit produced by her acts, there will be no maris ayin, and no detraction
of the spirit of Shabbos.5 Therefore she should not do any public prohibited acts
like gardening. She should not use a vacuum which causes a disturbance to the
Shabbos setting. She may not boil water or turn on lights in a dark room for the
sake of her employees. She may wash dishes, fold laundry, and turn off lights among other
tasks.
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1)Mishneh Berura 244:1 2)MB 247:4 3)MB 252:17 4)MB 244:30 5)MB
252:48
(Suggested reading: The Sanctity of Shabbos by Artscroll)
