The time-dependent-dielectric-breakdown (TDDB) distributions measured on a series of identical oxides at the same voltages have been shown to depend on the resistance and capacitance of the measurement test equipment. The TDDB distributions were shifted to shorter times if the impedance of the test equipment was lowered and/or the capacitance of the test equipment was raised. The lower resistances and higher capacitances allowed the nonshorting early electric breakdowns to develop into shorting, thermal, dielectric breakdowns. ©1997 American Institute of Physics.