(a) Upon the request of a public employer, group of public employees, or labor organization, the PERB shall determine an appropriate bargaining unit of public employees by identifying the specific class or classes of employees or identifying positions the employees of which shall be members of a unit; Provided, That no member of any class nor any person employed in any position identified for inclusion in an appropriate bargaining unit shall be required to join any labor organization representing such unit or participate in its activities, but no such person may join a labor organization representing another unit or participate in its activities. In determining the appropriateness of a bargaining unit, the PERB shall consider, but not be exclusively guided by:
(1) the common interests of the members of the proposed unit;
(2) the homogeneity of the wages, hours, and working conditions of the members of the proposed unit;
(3) the desire of the members of the proposed unit;
(4) the history of labor relations among the members of the proposed unit;
(5) the effects on collective bargaining of too fragmented or too broad units.
(b) No group of public employees shall be determined to be an appropriate bargaining unit if the group includes both professional and non-professional employees, unless a majority of the professional employees vote to be included in such unit and a majority of non-professional employees vote to be included in such unit.
(c) Police officers, corrections officers, firemen, prison guards, or other persons employed to protect the public safety and welfare and/or protect the property of a public employer shall be included in a single bargaining unit or in separate bargaining units, but no other public employee shall be a member of such unit.
(d) Supervisory employees of a public employer shall not be included in any bargaining unit with non-supervisory employees but may form one or more bargaining units.
(e) No public employee bargaining unit organized and represented by a labor union on the date of enactment of the act creating this chapter shall be deemed inappropriate or otherwise found severable except to the extent necessary to bring such unit into compliance with subsections (b), (c) and (d) of this section.