A ceiling lamp junction box assembly is composed of a base and an outer shell combined of two half portions that interlockingly combine to enclose electronic components contained therein. In addition, a protective plate is placed in a recess defined in the bottom of the outer shell to protect the electronic components and the outer shell during installation of the junction box. A dovetail portion present on the outer surface of the outer shell combines with a slot defined in the base to help improve rotational stability.