So I want to add cabin lights to my car fuse box. I have a fuse adapter 1 input 2 output. The original fuse goes in one slot on the adapter. The cabin lights will go on the other slot. the cabin lights are 12v 18watt 1.5amp. if the fuse connected to the fuse box is a 5 amp fuse, will the circuit with the lights only be drawing 1.5 amps?? or will 5amps be coming from the fuse? and the adapter only has a positive wire lead. will the negative just be connected to the metal frame of the car?