Two contests are on tap in the annual town election on Tuesday. Voting hours are 7 a.m. to 8 p.m. One of the races is a three-way contest for two seats on the Board of Selectmen between incumbents Daniel C. Bennett and Keith G. Lucy, and David A. Mills, a former town moderator. In the other race, Housing Authority member Ann Marie Penick is challenged by Michael Swindell. Town Moderator Patricia Fraizer and School Committee member Arthur Skarmeas are both running unopposed in their bids for reelection. Also running without opposition are the three candidates for three library trustee seats: incumbent Julie Curtis, Natalie Luca Fiore, and Frank Herschede, a former library trustee. The ballot also includes elections for six Town Meeting members for each of the eight precincts. In Precincts 2, 4, and 8 there are fewer ballot candidates than seats. The remaining seats in those precincts could be filled by write-in candidates. Meanwhile, the Board of Selectmen is expected to vote at its meeting on Thursday to fill the selectmen’s seat vacated by the recent resignation of Michael Powers. The appointment will be through the annual election in May 2014, which is also when Powers’s term would have expired.