To hardwire a radar detector to the fuse block, it is highly recommended to purchase our part number RA-PSC-B. This is a special power cord just for hardwiring our radar detectors. The cord is approximately 10 feet long. It has a radar connector on one end, and has bare wires and a fuse on the other end. The polarity of the wires is marked. Using this cord makes installation much easier. The polarity of the connector is center-tip-positive. If you do not purchase the hardwire cord, then you must cut the cigarette plug off the standard power cord. Then open the cigarette plug and see which wire color goes to the fuse. This is the (+) wire. Since the fuse was in the cigarette plug, you should install a fuse holder on the (+) wire. The fuse holder should be at the end of the cable, so that it will be near the power source (typically the fuse box). Remove the fuse from the cigarette plug and install it in the fuse holder. Radio Shack sells a suitable fuse holder, part number 270-1281. Installation: Please read the note following these instructions. 1. Connect the fused wire to a fuse in the fuse box. The fuse for the radio is recommended. To connect the wire to a fuse, it is recommended to use a “fuse tap” which can be found at Radio Shack and local auto stores. A fuse tap makes it easy to tap power from a fuse. You can connect the fuse tap to either side of the fuse – it does not matter. 2. Plug the cable into the radar detector and turn on the detector. 3. Turn on the ignition. 4. Touch the other wire to various screws under the dash. When the detector turns on, you have found a ground screw. Attach the wire to this screw. 5. Run the cable to the detector, avoiding the brake and gas pedals. This completes installation. NOTE: The above instructions are for negative-ground electrical systems. More than 99% of all vehicles are negative-ground. If you are unsure, ask your local car dealer. If your vehicle is positive-ground, then you must connect the un-fused wire to the fuse box, and connect the fused wire to a ground screw.