987. An Eiruv for Shabbos When Friday is Yom Tov

Eiruvin 8:13

If one placed his eiruv 1,500 cubits to the east of his home and he relied upon it for the first of two days, and he placed a second eiruv within 500 cubits to the west of his home and he relied upon it for the second day, the eiruv is valid because it was possible for him to access it on the first day.

Eiruvin 8:14

When yom tov falls on a Friday, it is not permitted to make an eiruv for Shabbos on yom tov, neither an eiruv for a courtyard nor an eiruv techumin. In such a case, one must make the eiruv on Thursday, the day before yom tov. If the two days celebrated as yom tov outside of Israel fall on Thursday and Friday, one should make both an eiruv for a courtyard and an eiruv techumin for Shabbos on Wednesday. If one forgot to make an eiruv in advance, he may make a conditional eiruv for a courtyard on Thursday and Friday (only one of which is yom tov under Biblical law). [This will be explained in the next halacha.] Making a conditional eiruv is not an option for an eiruv techumin.