What does NEC4 clause 60.1(15) mean?

Clause 60.1(15) deals with early partial take over. The event is that the Project Manager certifies take over of a part of the works before both Completion and the Completion Date. Both conditions must be met: the take over is before Completion of the whole of the works has been certified, and it is before the Completion Date. If the Contractor is late and the Client takes over a part after the Completion Date has passed, the paragraph does not apply, because the Client is then taking what it should already have had. The event turns on the Project Manager's certificate, so the certificate is the document to obtain. To rely on the paragraph the Contractor shows the certificate, the part it covers, the date, and that both Completion and the Completion Date were later. The event arises from the Project Manager's own certificate, so the Project Manager notifies it at the time of certifying; the Contractor should notify under clause 61.3 if that does not happen, and the eight week bar does not apply because the Project Manager should have notified. The change to the Prices is assessed under clause 63.1 as the effect of the take over on actual Defined Cost by the date of the certificate and forecast Defined Cost afterwards, plus the Fee, and the effect is usually indirect: loss of the taken over part for access or storage, working around the Client's occupation, additional protection and separation, out of hours working, split commissioning and maintaining separate temporary services. What most often goes wrong is that the Contractor treats early take over as good news and quotes nothing, then finds the working conditions have changed and the eight weeks have long passed, or that the quotation includes the cost of completing the part itself, which was always the Contractor's. Any delay to the Completion Date is assessed separately under clause 63 by the programming expert.