An adapter for mounting cable hangers to a mounting structure includes: a plurality of mounting panels, each mounting panel including a mounting hole, the mounting panels attached to each other at edges thereof, each mounting panel being disposed at an angle relative to its adjacent mounting panels; two base segments, each of the base segments attached to the edge of an endmost one of the mounting panels and extending therefrom toward the other of the base segments; wherein the mounting panels and the base segments define an interior of the adapter; two locking arms, each of the locking arms extending from an end of a respective base segment away from the interior of the adapter, each of the locking arms including a locking feature, the locking arms extending generally parallel to each other and defining a gap therebetween; wherein the adapter can be deflected from a relaxed state to a deflected state by forcing the locking arms toward each other; and wherein in the deflected state the adapter may be mounted to a mounting structure, with the locking arms inserted through a hole in the mounting structure and exerting outward pressure on edges of the hole, and the locking features maintaining the adapter in a mounted position on the mounting structure.