Dear Timmu,
The lofty purpose behind the statutory requirement of insurance under the ESI Act, 1948, is to provide certain benefits to employees in case of sickness, maternity, and employment injury so that the employer stands relieved of his liability in this regard. Due to the salary limit, if some employees escape the coverage of the ESI Act, 1948, the liability of the employer to compensate such employees in respect of death or injuries due to any employment accident or contracting of any occupational disease remains still at large under the Employees' Compensation Act, 1923. Though it is not mandatory under the EC Act, 1923, it is always safe to take employees' compensation insurance policy in respect of those employees not covered by the ESI Act, 1948, but falling under the definition of an employee u/s 2(dd) of the ECA, 1923.