  We consider interaction effects in a granular normal metal at not very low
temperatures. Assuming that all weak localization effects are suppressed by the
temperature we replace the initial Hamiltonian by a proper functional of phases
and study the possibility for a phase transition depending on the tunneling
conductance $g$. It is demonstrated for any dimension that, while at small $g$
the conductivity decays with temperature exponentially, its temperature
dependence is logarithmic at large $g.$ The formulae obtained are compared with
an existing experiment and a good agreement is found.
