Modernization of the existing ERMA FIRST's BWTS electrical installation. The works were carried out under the continuous operation of the ship in the North Sea. We have performed a full range of works, i.e. removal of the existing electrical installation, removal and securing of electrical switchboards and partial removal of cable trays. The installation stage included: fabrication and installation of foundations for the relocalized electrical switchboards, installation of new cable trays and penetrations, installation and termination of new cables according to the provided electrical diagrams, fabrication of new cable glands plates for switchboards enclosures and modernization of the main switchboard.