25 Pa. Stat. § 3016
If a method of election for any candidates or offices is prescribed by law, in which the use of voting machines is not possible or practicable, or in case, at any election, the number of candidates nominated or seeking nomination for any office renders the use of voting machines for such office at such election impracticable, or if, for any other reason, at any election the use of voting machines is not possible or practicable, the county election board may arrange to have the voting for such or all offices conducted by paper ballots. In such cases, ballots shall be printed for such or all offices, and the election conducted by the election officers herein provided for, and the ballots counted and return thereof made in the manner required by law for such offices, in so far as paper ballots are used.
25 P.S.§ 3016