actually, you should run the power wire straight to the battery and yes, you should put a fuse on it, but it does not come with Dei alarms, you must provide your own inline fuse. Some alarms such as code and audiovox provide an inline fuse. Most installers take the easy way and run the power wire to a constant power wire in the ignition harness because of the larger guage wire and it being in the same location of the ignition wire and starter wire, but you should, according to MECP(mobile electronics certified professional)certification, run the power wire to the battery, fused.