  We consider graphs made of one-dimensional wires connected at vertices, and
on which may live a scalar potential. We are interested in a scattering
situation where such a network is connected to infinite leads. We study the
correlations of the charge in such graphs out of equilibrium, as well as the
distribution of the currents in the wires, inside the graph. These quantities
are related to the scattering matrix of the graph. We discuss the case where
the graph is weakly connected to the wires.
