The invention concerns a method and a system for detecting an electric arc in an electrical installation (7) equipped with at least one sensor (5) capable of detecting temporal acoustic signals produced by the electrical installation (7), said method being characterised in that it comprises a device for analysis (3) configured to analyse any temporal acoustic signal (5) coming from said one or more sensors (5) by associating with said acoustic signal a corresponding parsimony measurement (m) whose value indicates whether the acoustic signal is an electrical arc signature or not.