53 Pa. Stat. § 23647
Elections of the eight elective members of the board shall be held annually on the second Monday of January of each year, beginning with the year one thousand nine hundred and thirty-six, and the said members, so elected, shall take office on the first day of February, following their elections. From and after the first day of February, one thousand nine hundred forty-eight, these eight members shall serve two year terms. The four from the rank and file members shall hold over until the first of February, one thousand nine hundred forty-nine, and, thereafter such members shall be elected on the odd numbered years. The other four elective personnel of the board shall be elected biennially on the even numbered years.
Vacancies among the elective members of the board shall be filled by the board at its next meeting, for the unexpired term.
The time and place of holding the annual elections shall be designated and fixed by the board, herein created.
53 P.S. § 23647