יום טוב שחל להיות סמוך לשבת בין מלפניה בין מלאחריה או שני י"ט של גליות יש לו לערב שני עירובין לשתי רוחות וסומך על איזה מהם שירצה ליום הראשון ועל העירוב שברוח השני ליום השני או מערב עירוב אחד לרוח אחת וסומך עליו לאחד משני הימים וביום השני יהיה כבני העיר וכאלו לא עשה עירוב ויש לו אלפים אמה לכל רוח בד"א בשני י"ט של גליות אבל בשני י"ט של ר"ה הרי הן כיום א' ואינו מערב לשני ימים אלא לרוח אחת וכן מתנה אדם על עירובו ואומר עירוב לשבת זו אבל לא לשבת אחרת לשבת אחרת אבל לא לשבת זו לשבתות ולא לימים טובים לי"ט ולא לשבתות:

Laws of an eruv of boundaries on a Yom Tov that falls adjacent to Shabbat. Contains 5 sections When Yom Tov falls adjacent to Shabbat — whether before or after it — or for the two days of Yom Tov observed in the diaspora, one may make two eruvs in two directions and rely on whichever he wishes for the first day and on the eruv in the other direction for the second day. Or he may make one eruv in one direction and rely on it for one of the two days, and on the second day he is like the townspeople as if he made no eruv, having two thousand cubits in each direction. This applies to the two days of Yom Tov in the diaspora, but the two days of Rosh Hashana are considered as one day, and one may only make an eruv for both days in one direction. Similarly, one may make a condition on his eruv and say "this eruv is for this Shabbat but not for another Shabbat," "for another Shabbat but not for this one," "for Shabbatot but not for Yom Tov," "for Yom Tov but not for Shabbatot."

One who makes an eruv for two days of Yom Tov in the diaspora, or for Shabbat and Yom Tov — even if it is one eruv in one direction for both days — the eruv must be present in its place during twilight of the first night and during twilight of the second night. How does he do this? He brings it to that place on Yom Tov eve or Shabbat eve and lets nightfall find him there, then takes it in his hand and returns. If the first night is Yom Tov he brings it to that place the next day and leaves it there until nightfall and eats it if the second night is Shabbat, or brings it back if the second night is Yom Tov — since they are two separate sanctities and not one day, so that we cannot say that by acquiring the eruv on the first night it takes effect for both days. If the eruv was eaten on the first day, it took effect for the first day and is not an eruv for the second. If he acquired Shabbat rest by foot on the first day, he must acquire it by foot on the second day — by going and standing at that place and resolving in his mind to acquire Shabbat rest there, saying nothing, since it is forbidden to make any preparation from Yom Tov for Shabbat or from Shabbat for Yom Tov even by speech. Certainly he cannot make an eruv with bread that was not already used on the first day, since he would need to declare it an eruv and would thereby be making a preparation. If he made the eruv on the first day with food and wishes to acquire by foot on the second day, it is valid. If he wishes to make the eruv with bread on the second day, he must use the same bread he used on the first day, needing to say nothing since the eruv was already declared — and thus he is making no preparation at all.

What we said about making two eruvs in two directions for two days applies only when it is possible for him to reach each of the two eruvs on the first day. But if it is impossible to reach the second day's eruv on the first day, the second eruv is not valid, since the mitzva of eruv requires it to be accessible as a meal while it is still day — and since he cannot reach this eruv on the first day, it is not accessible while it is still day. How so? If he placed his eruv two thousand cubits east of his home and relied on it for the first day, and placed a second eruv one cubit, one hundred cubits, or one thousand cubits west and relied on it for the second day — the second eruv is not valid, since on the first day the second eruv is not accessible to him while it is still day, as nothing remains for him to the west. But if he placed his eruv one thousand five hundred cubits east of his home and relied on it for the first day, and placed a second eruv within five hundred cubits west of his home and relied on it for the second day — it is valid, since he can reach it on the first day.

Yom Kippur is like Shabbat regarding both eruv of courtyards and eruv of boundaries.

Yom Tov observes the eruv of boundaries but not the eruv of courtyards.