Abstract: A wiring installation for electrical connections of a plurality of devices of a nuclear reactor, comprising: (a) a plurality of first multiwire cables each extending at least from certain ones of said devices and terminated with a first connector located above said cover at an end remote from said device, and (b) a plurality of second multiwire cables each for connection with a respective one of the first cables and each having a first section having a first multicables connector having a plurality of electrical contacts connected to respective wires of said section, said first multicables connector being common to at least ten independent first sections, and a second section having a second multicables connector having a plurality of electrical contacts connected to respective wires of said second section and corresponding to respective wires of said first section for removable connection to said first multicables connector.