Subject to regulation 5, a worker’s working time, including overtime, in any reference period which is applicable in his case shall not exceed an average of 48 hours for each seven days.

An employer shall take all reasonable steps, in keeping with the need to protect the health and safety of workers, to ensure that the limit specified in paragraph (1) is complied with in the case of each worker employed by him in relation to whom it applies.

Where a worker has worked for his employer for less than 17 weeks, the reference period applicable in his case is the period that has elapsed since he started work for his employer.

Paragraphs (3) and (4) shall apply to a worker who is excluded from the scope of certain provisions of these Regulations by regulation 21 as if for each reference to 17 weeks there were substituted a reference to 26 weeks.

For the purposes of this regulation, a worker’s average working time for each seven days during a reference period shall be determined according to the formula—

$\genfrac{}{}{0.1ex}{}{\mathbf{A}\mathbf{+}\mathbf{B}}{\mathbf{C}}$

where—

A is the aggregate number of hours comprised in the worker’s working time during the course of the reference period;

B is the aggregate number of hours comprised in his working time during the course of the period beginning immediately after the end of the reference period and ending when the number of days in that subsequent period on which he has worked equals the number of excluded days during the reference period; and

C is the number of weeks in the reference period.