The time dependences of electrical conduction and self-heating behaviors in high-density polyethylene filled with acetylene carbon black of 0.082 in volume fraction are studied in relation to voltage and ambient temperature. The characteristic decay current constant T-i, and the exponential growth time constant for self-heating T-g are determined for the samples under voltages U above the critical value U-c for the onset of self-heating. The influences of voltage and ambient temperature on T-i and T-g as well as the amplitude of the low-resistance to high-resistance switching are discussed on the basis of the random resistor network (RRN) model and the relationship between U-c and the intrinsic resistivity. (c) 2005 Wiley Periodicals, Inc.