A detection method and system are provided to detect an arc fault signal in a (HF) high frequency signal monitored on a power line. The HF signal is monitored on the power line over a predefined time period such as a half-cycle of a base frequency, and is partitioned into a plurality of smaller time-segmented signal segments over the period. For each signal segment, a first filter is applied to a signal spectrum of the signal segment to produce a filtered signal spectrum having one or more frequency intervals associated with power line communication filtered from the signal spectrum. HF signal content is checked in the filtered signal spectrum, and a binary value is assigned to the signal segment based upon a presence or absence of HF signal content. Thereafter, an arc fault event is determined based on the accumulated binary values of the signal segments.