Due-diligence to interpreting the Wiedemann-Franz law measurement

Considerable interest has arisen to understand the non-Fermi liquid behavior in strongly correlated systems by the Wiedemann-Franz law. Experimentally, this simple law holds remarkably well in wide ranges of carrier densities and masses as long as the collisions are elastic. This robustness makes the violation of the WF law a strong indicator for non-Fermi liquid behavior if it is not trivially broken. However, testing the WF law is a challenging experiment because it requires the measurement of the electronic thermal conductivity without contributions from other channels, i.e. phonons. The inevitable electrical contact resistance would also contaminate the Lorenz number measurement. Specifically, would the experimental test give a false positive or negative error due to the finite contact resistance? We will answer this question using a simple model in order to perform the due-diligence to interpreting the experimental results.