12.—(1) These Regulations do not apply to excluded installations; but the extent to which any apparatus or system comprised or to be comprised therein is relevant apparatus shall be determined in accordance with the provisions of this Part.
(2) In this regulation “excluded installation” means two or more combined items of relevant apparatus or systems put together at a given place (whether or not in combination with any other item) to fulfil a specific objective but not designed by the manufacturer (or manufacturers, where the items are made by different manufacturers) for supply as a single functional unit.