Ohio Rev. Code Ann. § 5715.04

County boards of revision shall, during the time fixed for their sessions, keep their offices open during the business hours on each business day, and their experts, clerks, and other employees shall devote their entire time to their respective duties during their term of office or period of service or employment; provided that boards may, with the approval of the tax commissioner, employ experts, clerks, or other employees with the understanding that such employed persons shall devote only a part of their entire time to their respective employments.