Example embodiments of the invention perform updating of arc-fault detection protection software in a dual function/combination arc-fault circuit interrupter (DF/CAFI) device, without requiring any hardware changes to the device. Maintenance software running in a processor in the device synchronizes downloading the updated protection software as packets of modulated data from a host device, downloaded over an electric power line connected to the device. The modulated data on the power line is sensed by a current sensor of the device and is filtered, demodulated, and sampled by the device. The maintenance software then assembles packets of the demodulated and sampled data and loads them into memory in the device as the updated arc-fault detection protection software.