A Jew who lives outside Israel and visits Israel for Yom Tob must observe both days of Yom Tob. Even though residents of Israel observe only one day of Yom Tob, a Jew who visits Israel from the Diaspora must observe the second day, just as he does at home. Since he visits only temporarily and plans to return home after Yom Tob, he must observe the second of Yom Tob.
The question arises whether a person in this case may ask an Israeli to perform Melacha (activity forbidden on Shabbat and Yom Tob) on his behalf on the second day of Yom Tob. If, for example, the visitor needs something delivered or picked up, or he needs the lights turned on, may he ask an Israeli resident who does not observe Yom Tob on that day to perform the given task?
This issue is subject to a debate among the Halachic authorities. Hacham Ovadia Yosef concludes that it is, indeed, permissible for a visitor from the Diaspora to ask an Israeli resident to perform Melacha for him in this case. He explains that this situation may be compared to the case discussed by the Shulhan Aruch concerning a person who accepted Shabbat early, before sundown, as many people do during the summer months. According to the Shulhan Aruch, a person who accepted Shabbat earlier may ask somebody who had not yet accepted Shabbat to perform Melacha on his behalf. For example, if a man accepted Shabbat early on Friday afternoon in the summer, and upon arriving home he discovers that some lights were not turned on, he may ask family members or others who have not yet accepted Shabbat to turn on the lights. The Sages did not enact a prohibition against asking a fellow Jew to do Melacha in this case because it is readily obvious that the person being asked has yet to accept Shabbat, and there is thus no concern for suspicion or confusion.
Similarly, Hacham Ovadia writes, we should allow a visitor in Israel to ask an Israeli resident to perform Melacha for him on the second day of Yom Tob, since the Israeli resident is not observing Yom Tob on that day. Hacham Ovadia adds that the observance of the second day of Yom Tob is required only on the level of Rabbinic enactment, as opposed to Torah law, thus giving us another reason to rule leniently in this regard.
This is the ruling of a number of other authorities, as well, including Rav Shlomo Zalman Auerbach (Jerusalem, 1910-1995) and Rabbi Moshe Stern of Debereczyn (in his work Beer Moshe).
It should be noted that if a Jew in the Diaspora owns a factory or other business in Israel, it is permissible for the business to operate in Israel on the second day of Yom Tob. Since Israeli residents do not observe that day as Yom Tob, they may work, even if the business is owned by a Jew who must observe that day as Yom Tob. This was the ruling given by Rav Moshe Feinstein (Russia-New York, 1895-1986).
Summary: If a Jew who lives in the Diaspora visits Israel for Yom Tob, he must observe the second day of Yom Tob, but he may ask Israeli residents to perform Melacha on his behalf on that day. Similarly, one who has accepted Shabbat may ask a fellow Jew who has not accepted Shabbat to perform Melacha on his behalf.
