The classified civil service and provisions of this chapter shall include all full paid employees of the fire department of each city, town or municipality coming within its purview, except that individuals appointed as fire chief after July 1, 1987, may be excluded by the legislative body of the city, town, or municipality. All appointments to and promotions in said department shall be made solely on merit, efficiency and fitness, which shall be ascertained by open competitive examination and impartial investigation. No person shall be reinstated in, or transferred, suspended or discharged from any such place, position or employment contrary to the provisions of this chapter.