Got the livescope and need advice extending the power wire. Will need to splice in 15 ft. of 10/2. A drawing in the instructions appears to indicate i should cut the garmin power cable splicing 8 in. of the connector end (that connects to black box) to my wire and spice in 8 in. of the positive wire on the other end (this includes the inline fuse and then connects to the battery). Scary thing cutting up the power cable to insert this extension wire. Is this right? Garmin won't reply to my email.