A halogen light fixture for mounting under a cabinet and over a counter surface, as in a kitchen, has a housing of continuous cross section between opposite end caps adaptable to fixtures of varying lengths. Screw fasteners pass through aligned openings in the housing and the end caps for attachment to the cabinet underside, and spacers integral to the end caps provide for air flow between the fixture and the cabinet. A partition also extending between the end caps provides a closed wiring compartment and some or all of the electrical components of the fixture, including lamp sockets and power switch can be mounted on the partition for ease of assembly and access.