An adapter structure which cooperates between a modular electrical distribution unit and a light fixture to facilitate electrical connection therebetween. The adapter structure includes an adapter module having an insulative housing containing electrical conductors extending therethrough and defining connectors at input and output ends thereof. The housing mounts directly to the light fixture, preferably within and extending through a knock-out port in a wall of the light fixture, and a plug-type connector at the output end of the adapter structure can be plug engaged with a compatible connector associated with a electrical power distribution unit. The output end of the adapter has a gripping conductive socket structure which enables pigtail conductors associated with the light fixture to be directly plugged therein.