Onboard electrical power supply network (110, 210, 310, 510) in a vehicle (100, 200) comprising a plurality of electrical energy sources (101, 102, 201, 202, 301, 302, 501, 502, 503), comprising at least two distribution boxes (111, 112, 211, 212, 213, 221, 222, 223, 311, 312, 313, 511, 512, 513) each comprising: - at least one internal distribution bus (401, 402, 601, 602, 701) that can be connected to said electrical energy sources; - at least two output switches (41, 42, 61, 62, 71, 72) each for supplying power to at least one electrical consumer (31, 32, 51, 52) distinct from the vehicle from the internal distribution bus; - a driver processor (403, 603, 703) for driving said output switches so as to distribute a consumption load between the electrical consumers in association with different operating modes of the vehicle, the network comprising a coupling box (305, 505, 506) connected to each electrical energy source and a set of electrical wires (81-86, 91-98) to connect each distribution box (311-313, 511-513) to each coupling box (305, 505, 506), the network being characterized in that each coupling box (505, 506) comprises: - a selector (507, 508) comprising a plurality of switching paths all connected upstream to the same pole (+) of an energy source (501, 503), and each connected downstream to an electrical wire exiting the coupling box; - a control processor (509, 520) for controlling the selector in order to control and monitor an on/off state of each path connected to that of the electrical wires to which said same energy source pole is assigned. - at least one internal distribution bus (401, 402, 601, 602, 701) that can be connected to said electrical energy sources; - at least two output switches (41, 42, 61, 62, 71, 72) each for supplying power to at least one electrical consumer (31, 32, 51, 52) distinct from the vehicle from the internal distribution bus; - a driver processor (403, 603, 703) for driving said output switches so as to distribute a consumption load between the electrical consumers in association with different operating modes of the vehicle, the network comprising a coupling box (305, 505, 506) connected to each electrical energy source and a set of electrical wires (81-86, 91-98) to connect each distribution box (311-313, 511-513) to each coupling box (305, 505, 506), the network being characterized in that each coupling box (505, 506) comprises: - a selector (507, 508) comprising a plurality of switching paths all connected upstream to the same pole (+) of an energy source (501, 503), and each connected downstream to an electrical wire exiting the coupling box; - a control processor (509, 520) for controlling the selector in order to control and monitor an on/off state of each path connected to that of the electrical wires to which said same energy source pole is assigned. - a selector (507, 508) comprising a plurality of switching paths all connected upstream to the same pole (+) of an energy source (501, 503), and each connected downstream to an electrical wire exiting the coupling box; - a control processor (509, 520) for controlling the selector in order to control and monitor an on/off state of each path connected to that of the electrical wires to which said same energy source pole is assigned.