The theoretical description of nonequilibrium electrochemical systems involves nonobservable variables such as diffusion potential (dp). In the recent years, a new way based on the observable electric potential (oep) has been developed. In this work we provide an illustration of the potential applications of the oep formalism by considering a system of great practical interest: the salt bridge. This system has been chosen because, in spite of its widespread use for many decades, a sound theoretical base for the salt bridge concept is still lacking. The oep is offered as a good alternative in the salt bridges. Moreover it involves a ternary electrolyte system, with a common anion at uniform temperature and pressure, which complexity is enough to make useful this application example of the oep formalism.