14. After regulation 20 there shall be inserted the following regulation—
“Acquisitions of water, gas or any form of power, heat, refrigeration or ventilation
20A. Where goods such as are described in regulation 20(1)(a), (b) or (c) above are acquired from another member State and the whole or part of any consideration comprised in the transaction in pursuance of which the goods are acquired is payable periodically, or from time to time, goods shall be treated as separately and successively acquired on each occasion that the supplier issues, in respect of the transaction, an invoice such as is described in regulation 18A.”.