Abstract: An expansible load-bearing junction box hanger assembly adapted for installation from beneath the ceiling and through a junction box opening in the ceiling, includes a pair of walls having a plurality of spike protrusions to engage two spaced adjoining ceiling joists and an elongated linearly expanding brace device which is aligned with and connected between the walls. The brace device expands from a short to a longer length to force each of the walls to contact and engage their respective ceiling joists. Each wall is provided with a receiving groove adjacent to the spike protrusions. The hanger assembly further includes an alarm device, a battery cell, and a contact switch disposed in each receiving groove and actuated when the walls engage their respective ceiling joists. The contact switches electrically connect the alarm device to the battery cell to operate the alarm device when actuated, thereby indicating that the hanger assembly has fully engaged the ceiling joists.