An adapter for use with a U-section longitudinally extending power track has a base adapted to fit in the slot and a head adapted to fit outside the slot on the track so that an electrical device can be connected via the adapter to the conductors in the track. A first operating shaft extending along and pivotal about an axis in the housing carries contact fingers pivotal on rotation of the first shaft between a retracted position recessed in the base and a contacting position projecting from the base and, when the base is fitted to the slot, engaging the conductors. A second operating shaft extends along and pivotal about the axis in the housing. A second switch assembly connected to the second shaft and operable thereby on rotation of the second operating shaft to connect and disconnect the contact fingers with phase contacts on the housing.