In any city or town which accepts the provisions of this section, inspector of buildings, building commissioner or local inspector so employed and designated under this section shall be appointed for a minimum term of three years and such three year term or more shall not be diminished by an unexpired term of a predecessor, and he shall not be removed from office during his term except for just cause and after a hearing has been held on charges by and before the appointing authority.
Mass. Gen. Laws ch. 143, § 3Y