Explanation:

Section 64(4) in The Factories Act, 1948
(4) In making rules under this section, the State Government shall not exceed, except in respect of exemption under clause (a) of sub-section (2) the following limits of work inclusive of overtime:—
(i) the total number of hours of work in any day shall not exceed ten;
(ii) the spread over, inclusive of intervals for rest, shall not exceed twelve hours in any one day:
Provided that the State Government may, in respect of any or all of the categories of workers referred to in clause (d) of sub-section (2), make rules prescribing the circumstances in which, and the conditions subject to which, the restrictions imposed by clause (i) and clause (ii) shall not apply in order to enable a shift worker to work the whole or part of a subsequent shift in the absence of a worker who has failed to report for duty;
[(iii) the total number of hours of work in a week, including overtime, shall not exceed sixty;]
[(iv) ] the total number of hours of overtime shall not exceed fifty for any one quarter.
Explanation .—“Quarter” means a period of three consecutive months beginning on the 1st of January, the 1st of April, the 1st of July or the 1st of October.]