2.—(1) Subject to regulation 10, an election with a view to the issue of a contracting-out certificate—
(a)may only be made—
(i)after notices to make such an election have been given by the employer in accordance with regulation 3, and
(ii)within the period after the expiry of those notices which is specified in regulation 5, and
(b)shall be made in writing to the Department and shall include the particulars specified in regulation 6.
(2) An employer may elect that an employment of earners in an employment shall be contracted out by reference to a scheme in relation to all earners in that employment with the exception of those mentioned in either or both of sub-paragraphs (a) and (b)—
(a)where an earner in an employment to which the scheme relates opts in writing not to join or, as the case may be, not to remain as a member of any contracted-out employment to which the scheme relates, any earner who so opts, and
(b)in a case where it is possible for one or more earners to be unable to complete 5 years' service in that employment as members of that scheme before reaching the normal pension age of that scheme, the earner or earners whose length of service (consisting of service in that employment as a member of that scheme, or linked qualifying service in relation to such service, or both) falls short of a minimum length of service (not exceeding 5 years) specified in the rules of the scheme and who cannot (so far as is known when the contracting-out certificate is issued, or if later in the case of a particular earner, when he enters the employment) complete such a minimum length of service before reaching the normal pension age of the scheme.