Various non-equilibrium effects as a result of a voltage can be observed in superconductors where either the length ℓ, the width w or the thickness d is constricted. The dimensions of the constriction is normally chosen to be smaller than the coherence length ξ in order to avoid instabilities. We review some effects found in systems where two large superconductors are connected by a constriction with d, w<ξ (strips), d, ℓ<ξ (wide bridges) and d, w, ℓ<ξ (microbridges)