(1) The civil service commission shall provide for promotion in the classified civil service on the basis of ascertained merit, seniority in service and standing obtained by competitive examination, and shall provide, in all cases where practicable, that vacancies shall be filled by promotion from the members of the next lower rank as submit themselves for the examination and promotion.
(2) The civil service commission shall certify to the appointing power the names of not more than five applicants having the highest rating for each promotion.