An arc fault detection system samples a high frequency signal on a power line sequentially at different frequency regions according to a frequency hopping sequence, which is repeated a number of times over a predefined period. The different frequency regions include at least one region with a carrier for power line communication on the power line and at least one region without a carrier for power line communication on the power line. The system obtains energy measurements for each frequency region based on the sampled signals, computes an energy level for each frequency region based on the measurements for each region, and assigns a binary value to each region according to the corresponding energy level. The binary value represents a presence or absence of signal content in the frequency region. The system determines a presence or absence of an arc fault based on the binary values for the frequency regions.