Electric power supply method for an on-board domestic network in a passenger cabin using equipment referred to as domestic equipment requiring voltage levels of terrestrial domestic type, characterized in that , primary electric power sources being provided over at least two primary networks , the method consists in: - connecting the primary networks in parallel to a single on-board domestic network for supplying said domestic equipment in the cabin with power through conversion interfaces (41, 42; 40) for converting primary alternating current to domestic-level voltage and frequency, each primary network being coupled to the domestic network through at least one interface (41, 42; 40); - parallelizing the conversion interfaces (41, 42; 40) by measuring data on the level of the electric parameters provided (L1) by each interface (41, 42; 40) in order to regulate (L1, L2) the sharing of the primary power sources depending on their availability and provide continuity of level of service over the domestic network by means of at least one unit for processing the measured data and for controlling regulation in a control loop (L1, L2) and bidirectional transmission (T1; T2) of said data; and - maintaining the quality criteria of each primary network and domestic quality criteria of the domestic network by means of filtering, level balancing and power-factor correction (D1, D2) in each conversion interface (41, 42; 40) connected upstream with each primary network and connected downstream with the domestic network , each conversion interface (41, 42; 40) comprising two functional stages (E1, E2), upstream and downstream of a galvanic isolation electric transformation , respectively, and each functional stage (E1, E2) comprising two adaptation levels, a level (D1, D2) dedicated to maintaining the quality criteria connected with the primary network and the domestic network, respectively, and a level (7; 71, 72) for voltage and/or frequency conversion connected with the galvanic isolation . - connecting the primary networks in parallel to a single on-board domestic network for supplying said domestic equipment in the cabin with power through conversion interfaces (41, 42; 40) for converting primary alternating current to domestic-level voltage and frequency, each primary network being coupled to the domestic network through at least one interface (41, 42; 40); - parallelizing the conversion interfaces (41, 42; 40) by measuring data on the level of the electric parameters provided (L1) by each interface (41, 42; 40) in order to regulate (L1, L2) the sharing of the primary power sources depending on their availability and provide continuity of level of service over the domestic network by means of at least one unit for processing the measured data and for controlling regulation in a control loop (L1, L2) and bidirectional transmission (T1; T2) of said data; and - maintaining the quality criteria of each primary network and domestic quality criteria of the domestic network by means of filtering, level balancing and power-factor correction (D1, D2) in each conversion interface (41, 42; 40) connected upstream with each primary network and connected downstream with the domestic network , each conversion interface (41, 42; 40) comprising two functional stages (E1, E2), upstream and downstream of a galvanic isolation electric transformation , respectively, and each functional stage (E1, E2) comprising two adaptation levels, a level (D1, D2) dedicated to maintaining the quality criteria connected with the primary network and the domestic network, respectively, and a level (7; 71, 72) for voltage and/or frequency conversion connected with the galvanic isolation . <EOS>