A circuit fuse adapter, also known as a fuse tap or fuse piggyback, is a device that allows you to add an additional circuit to an existing fuse in your vehicle's fuse box. It essentially taps into an existing fuse slot and provides a separate connection point for a new circuit. To add a circuit fuse adapter, follow these steps: 1. Identify a fuse slot in your vehicle's fuse box that has the appropriate amperage rating for the circuit you want to add. Make sure to consult your vehicle's manual or a fuse diagram to determine the correct fuse slot. 2. Turn off the ignition and remove the key from the vehicle. 3. Locate the fuse you want to tap into and remove it from the fuse box using a fuse puller or a pair of needle-nose pliers. 4. Insert the circuit fuse adapter into the empty fuse slot. The adapter should have two fuse slots, one for the existing fuse and one for the new circuit. 5. Insert the existing fuse into the appropriate slot on the adapter. 6. Connect the new circuit to the remaining slot on the adapter. This can be done using a wire connector or by soldering the wires together. 7. Ensure that all connections are secure and insulated to prevent any short circuits or electrical hazards. 8. Once everything is properly connected, reinsert the adapter with the fuses back into the fuse box. 9. Turn on the ignition to test the new circuit. If everything is working correctly, the new circuit should have power.