Hello! I have a set of Universal 4-Channel switches that turn on and off by wireless remote. And I am using each channel about 15 amps. Follow the instructions to connect the 2 poles directly to the battery. But I only want this unit has power after I turn on the key. Can I connect it to Fuse Box? I am worried that connecting to the fuse box will damage the circuit when using high wattage lamps. Or can I use a relay harness connect before this unit? Because the relay harness has a manual toggle switch that uses the trigger low-current from fuse box to toggle the high-current from battery. Does that damage anything?