Auxillary Fusebox Install - Land Rover Technical Blog Land Rover Technical Blog Admin. Log in; Auxillary Fusebox Install. Category: Technical Articles. For reference purposes, here’s my Defender auxillary fusebox install. We begin in the battery box: Inside the battery box. The supply wires to the fusebox are 16mm², rated for 100 amps. As such, there is an in-line 100 amp fuse mounted to Auxiliary Fuse Box? | LandyZone - Land Rover Forum wwwyzone››Defender 90 / 110 / 1304inue the positive and negative feed from the breaker to the AUX fuse box with 6mm² 50 Amp cable. 5 2mm² cable to wire positive and negative feeds to the carling switches from the appropriate terminals of the AUX fuse panel. 6all the appropriate fuse for the application running from the carling switch example GPS charger: 5 amp.