Abstract: An extensible bar hanger assembly designed to support recessed lighting fixtures in a ceiling. A pair of double L shaped bar members, one on each side of a fixture, are extensible and contractable to adjust between ceiling joists or other ceiling support to provide a rigid mount for the fixture. The bar members are each longitudinally domed to provide interlocking and each include an elongated slot extending the major length of each respective bar. One end of each bar includes a side extending barbed tab which is secured to adjacent ceiling joists. The opposite ends of the bar members include precisely formed locks. In the case of one bar member, the lock is an offset T shaped foot. The other end lock is a trapezoidal shaped head. These ends lock the joints together by interlocking through the elongated slots in the opposite bar member.