1. Board determination of an appropriate bargaining unit shall be upon petition filed by a public employer, public employee, or employee organization.
2. Within thirty days of receipt of a petition, the board shall conduct a public hearing, receive written or oral testimony, and promptly thereafter file an order defining the appropriate bargaining unit. In defining the unit, the board shall take into consideration, along with other relevant factors, the principles of efficient administration of government, the existence of a community of interest among public employees, the history and extent of public employee organization, geographical location, and the recommendations of the parties involved.
3. Professional and nonprofessional employees shall not be included in the same bargaining unit unless a majority of both agree.