The Shulhan Aruch (Orah Haim 440) addresses the question of whether one may allow a non-Jew to enter his home on Pesah with Hames. Does the Torah prohibition against owning Hames require one to prevent a non-Jew from bringing his own Hames into the Jew’s home during Pesah?
The Shulhan Aruch notes the Halachic principle "Shelecha I Ata Ro’eh Abal Atah Ro’eh Shel Aherim" – the prohibition against having Hames in one’s possession during Pesah applies only to a Jew’s own Hames. There is no prohibition at all against seeing a non-Jew eating Hames on Pesah, or having a non-Jew bring his Hames into one’s home on Pesah.
Therefore, if one needs some kind of repair done in his home during Pesah that is necessary for the Yom Tob, and he calls a non-Jewish worker – such as a plumber or electrician – he does not have to prevent the worker from bringing Hames into the home. Of course, if the worker left crumbs, they should be swept and discarded, but there is no need to prevent the worker from bringing Hames into the home.
For that matter, the Jew may allow the non-Jewish worker to eat his Hames food in his home. Even if the worker brings a pizza or a sandwich, he is allowed to eat his food at the table in the Jew’s home. The table should then be thoroughly cleaned after the non-Jew finishes eating so that it may be used later by the Jew.
The Mishna Berura (Rav Yisrael Meir Kagan of Radin, 1839-1933) adds, however, that the Jew should not eat at the table with the non-Jew in such a case, due to the possibility of a crumb of Hames going into the Jew’s food. Even if the Jew eats on a separate plate, and even if there is some divider between them, it is impossible to ensure that no crumbs from the non-Jew’s Hames food will fly into the Jew’s food. (The Mishna Berura adds that even if one appoints somebody to stand there and make sure he does not mistakenly partake of the non-Jew’s Hames, this does not prevent crumbs from getting into his food.) Therefore, although the gentile is allowed to eat his Hames meal in the Jew’s home, the Jew should not sit and eat with him.
Practically speaking, of course, we ensure not to allow any Hames into the home during Pesah. Nevertheless, if it happens that a non-Jewish worker is in the home and wants to eat his Hames, he should be allowed to do so, as discussed.
Summary: If a non-Jew comes into a Jew’s home during Pesah – such as in the case of a non-Jewish repairman – the non-Jew should be allowed to bring his food into the home and even eat it in the home, even if it includes Hames. The Jew should not eat together with the non-Jew in such a case, and the table must be thoroughly cleaned after the non-Jew finishes eating.