(a) In any city of the first class owning and operating municipal light and power systems, the boards of commissioners or other controlling or managing bodies in control of such systems are authorized to provide plans of social security, group insurance, hospitalization insurance, old age pension and retirement pay benefits, or any of these benefits, for any or all employees of municipal light and power systems under such plan or plans as the boards of commissioners deem most desirable.
(b) The plans for any or all benefits may include payments from both the boards of commissioners and the employees, or either of them, and may be underwritten by some solvent insurance company or by a fund set up and maintained by the boards of commissioners from the funds of the light and power systems, except such funds as are set aside for specific purposes, the employees, or both or either of them.
(c) The plans, when perfected, shall supersede all other plans provided by law.