Section 125(3) in Delhi Prisons (Inspection, Meetings and Duties of Officers) Rules, 1988
(3)for a convict warder, that(a)his substantive sentence is not less than three years and that he is a prisoner of the casual class;(b)he has served as a convict-overseer for not less than (a) six months in the case of a prisoner whose term does not exceed three years or (b) one year in the case of a prisoner whose term exceeds 3 years;(c)his work as a convict-overseer has been satisfactory;