Is Workmen/Employee compensation Act mandatory for all private firms

Please advise if it is necessary for all private firms to cover all employees under WC policy even if they have insurance cover from various policies like group accidental, term life & health. Are all employees eligible under WC policy? what are the regulatory rules for WC policy.
Regards
N S

The benefits of Mediclaim or GPA is less than WC Policy so can be concluded as WC is compulsory.

Dear NS
If your establishment is covered under ESI there is no need to take WC but to have in absence. The WC policy is a comprehensive plan to combat all that liability your establishment likely to face incase of any accident caused to workman. In case of any liability arises the establishment has to handle not by the policy held in name of workman.