(1) For the purpose of this Act, "collective redundancies" means dismissals effected by an employer for one or more reasons not related to the individual concerned where in any period of 30 consecutive days the number of such dismissals is - (a) at least 5 in an establishment normally employing more than 20 and less than 50 employees, (b) at least 10 in an establishment normally employing at least 50 but less than 100 employees, (c) at least ten per cent. of the number of employees in an establishment normally employing at least 100 but less than 300 employees, and (d) at least 30 in an establishment normally employing 300 or more employees.

(2) For the purpose of calculating the number of redundancies where the number of dismissals is at least 10 in an establishment normally employing more than 20 and less than 100 employees, terminations of a contract of employment which occur to the individual workers concerned shall be assimilated to redundancies provided there are at least 5 redundancies.