How to Add Wiringto an Automotive FuseBox. Locate the red (positive) wirefrom the electrical equipment and connect the end to the "out" terminal on the spare fuse. Remove the fuseusing your fingers and slide the wireinto the connector. It clips in place. Attach another red wireto the "in" terminal on the fuseusing the same method. How to Add Wiring to an Automotive Fuse Box | eHow UK Was this helpful?