(1) An active member of this system who is unable to perform firefighter service due to a physical or mental condition that was not incurred in the line-of-duty may apply to the office for a disability retirement benefit subject to the following provisions:

1. (a) if the member has less than five years of service credit in this system, disability benefits are not payable; and
2. (b) if the condition is classified by the office as a nonline-of-duty disability and if the member has five or more years of service credit in this system, the member shall be granted a disability retirement benefit subject to Section 49-16-602.