  The paper presents the first-principle calculation of the electron-phonon
coupling and the temperature dependence of the intrinsic electrical resistivity
of the zirconium-hydrogen system with various hydrogen concentrations. The
nature of the anomalous decrease in the electrical resistivity of the Zr-H
system with the increase of hydrogen concentration (at the high concentrations
of H/Zr$>$1.5) was studied. It was found that the hydrogen concentration, where
the resistivity starts to decrease, is very close to the critical concentration
of the $\delta-\varepsilon$ phase transition. It was shown that the tetragonal
lattice distortion due to the $\delta-\varepsilon$ phase transition of the Zr-H
system eliminates imaginary phonon frequencies and the strong electron-phonon
coupling of the $\delta$ phase and, as a result, leads to the reduction of the
electrical resistivity of the Zr-H system at a high hydrogen concentration.
