At the electric-thermal equilibrium state, the nonlinear conduction behaviors of high-density polyethylene/acetylene carbon black composites crosslinked with electron-beam. irradiation have been studied in wide ranges of electric field and ambient temperature. Critical electric field E-0.5 at the global electrical breakdown and the corresponding apparent resistivity are related to the intrinsic resistivity at given ambient temperatures. The relationship between the nonlinear conduction and the intrinsic positive temperature coefficient effect of resistivity is established by a discussion of E0.5 as a function of the macroscopic resistivity temperature coefficient. (c) 2006 Wiley Periodicals, Inc.