A luminaire (i.e., a light fixture) is typically a complete lighting unit consisting of one or more lamps, socket, and optical devices for distributing light. A recessed luminaire is an example of a luminaire that is installed behind a structure such as a ceiling. Recessed luminaires are used in both commercial and residential applications. For example, a recessed luminaire is typically mounted on support structures behind a ceiling wall that has an opening to allow light from the recessed luminaire to illuminate an area below the ceiling wall.
Various support systems have been employed to support recessed luminaires. For example, recessed luminaires are often suspended between support structures such as joists and T-bar structures. To illustrate, a recessed luminaire may be supported by hanger bars that extend between parallel support structures. Generally, hanger bars need to have adequate strength and rigidity to reliably support a recessed luminaire. Further, because the spacing between the support structures such as the joists of a ceiling structure may vary, adjustability of the lengths of hanger bars is desirable for easy installation as well as for compatibility with different support structures. However, unintended detachment of hanger bar members from each other can make installation of hanger bars difficult, which can waste time and money.
Thus, adjustable hanger bars that have structures that prevent or reduce risk of unintended detachment of the hanger bars from each other are desirable.