In each district the board of education may designate some person to act in place of any officer or employee during the absence, disability or disqualification of any such officer or employee subject to the provisions of section 18A:17-13.
The act of any person so designated shall in all cases be legal and binding as if done and performed by the officer or employee for whom such designated person is acting but no person so acting shall acquire tenure in the office or employment in which he acts pursuant to this section when so acting.