A support rail and housing assembly is mountable on a housing base. The housings are equipped with electrical contact and/or functional elements which can be strung together. The support rail is mountable on the mounting base even when the housings have already been arranged on the support rail before the support rail is mounted. The support rail is secured to the mounting base by two or more mounting pins which have been placed before the support rail is mounted to the mounting base. The mounting pins and the support rail are designed to correspond to each other such that the support rail can be placed on the mounting pins and locked thereto without using a tool.