The optimum inspection strategy of an m-out-of-n:G nuclear reactor protective system with nonidentical units is analyzed in this work. A 2-out-of-4:G system is used to formulate a multi-variable optimization problem to determine (a) the optimum order of supervision of the units and (b) the optimum supervision intervals between units. The case of systems with identical units is a special case of the above. Numerical results are derived using a computer algorithm.