In this paper, we present a novel method based on a single-phase active power filter (APF) for series arc faults detection in an AC electrical installation. The APF's reference current is used as the starting point for our method tested on a large variety of loads: resistors, vacuum cleaner, rotary drill, dimmer and AC-DC power supplies. Firstly, the proposed method is validated at the simulation level using the Matlab software and then experimentally using the Hardware-In-the-Loop (HIL) approach with an FPGA Altera Stratix III prototyping board. The results obtained in this work show that series arc faults can be successfully detected with an APF, only by updating its digital control with the arc fault detection functionality, instead of designing from the very beginning an arc-fault detection specific device.