Abstract: A void-forming preform for installing a light fixture in a pavement, such as a poured concrete slab, or other structure comprises an upper chamber for receiving the light fixture, a ledge for supporting the light fixture, and a lower chamber for holding a length of wiring entering the lower chamber through a port. In a further embodiment, adjustable standoffs are formed in the bottom of the preform. The standoffs may be bent down to provide support for the preform on a pavement base prior to forming the pavement, and allow easy and fine adjustment of the height of the preform in relation to the final grade of the pavement.