No person shall be eligible to the office of trustee of schools who is not a resident of the township and at least 18 years of age. If there are 3 or more school districts in a township which are subject to the jurisdiction of the trustees of schools of that township, no 2 trustees shall reside, when elected, in the same school district; except that in townships in which at least 90% of the electors reside in one school district which is subject to the jurisdiction of the trustees of schools of that township, this restriction shall not apply. No person shall be eligible to the office of trustee of schools and school director or school board member at the same time.
     This Section does not apply to trustees appointed under subsection (b) of Section 5-2.