The statistical distributions of break‐arc durations have been examined as functions of arc current and number of operations under both ``clean'' and contaminated conditions. Exponential distributions were found for arcs between clean palladium electrodes operating below 0.9 A. At higher currents a Gaussian‐ (normal) type distribution was observed. Under highly contaminated conditions the Gaussian distribution was observed at all current levels examined. These distributions have been discussed in terms of the ``ionic‐burst'' mechanism and thermionic emission. A model for the so‐called activation or arc‐duration enhancement of arcs is presented.