Horn, who was named temporary acting fire chief in January after Charlie Johnson stepped down due to a job-related medical condition, will become fire chief when Johnson's resignation or medical disability becomes official later this spring.
While unanimously picking Horn, who has no firefighter experience, selectmen reserved the right to dismiss him in five years. If he is asked to leave the post, selectmen said Horn will still retain his job as police chief.
The town now plans to hire a deputy fire chief to work directly under Horn and oversee actual firefighting.
Several firefighters were contacted after the vote but declined to comment.
A handful of residents, however, said after the meeting they believe Horn's appointment will lead to resignations among the call firefighters.
While resident Caryn Gomes said Horn is an excellent police chief, she is concerned that making him a fire chief takes him away from his area of expertise.
"They made a huge mistake," Gomes said. "They're going to have people resign and they'll have to rebuild the department from scratch."
Kevin Haley, meanwhile, said he believes the choice is going to make the town less safe.
"We know enough about it to know it's not a good idea," Haley said. "At least they were smart enough to hire a deputy chief, but it's not enough."
But explaining his vote, Selectman Ken O'Brien said he expects Horn will fix the Fire Department's inequitable pay system, inadequate training and flawed communication with the town.
"As selectmen for the town of Mendon, one of our most important duties is to assure the safety of the community," O'Brien said. "Having the same person responsible for both departments, communication between the departments and the board will not be an issue."
Selectman Sharon Cutler said she reached the same conclusion after talking to town administrators, firefighters and fire chiefs from around the state. By looking at the town of Lynnfield in particular, because it also has a combined police and fire chief, Cutler said she was comfortable appointing Horn.
"He is already well-versed in EMT services, which makes up 61 percent of the department's services," she said.
Comforted that the board can ask Horn to relinquish his Fire Department responsibilities in five years if he is not working out, Cutler made her vote.
Selectmen Chairman Dennis Shaheen expects Horn will continue preparing a water resource plan and an emergency management plan for a school disaster. Horn will also be asked to develop the relationship between the Police and Fire departments and the town, strengthen the call firefighter department and build a more efficient working relationship with surrounding towns.
"He certainly is extremely capable, well versed in the various disciplines needed to run these two departments," Shaheen said. "I give him my wholehearted support. I hope that most people do."
"We could easily interview 20 or 30 candidates and not have a man as capable as Ernie," Shaheen added.
