I am going to be running another amp to my system. I have 4 gauge already run but if i use a distribution block then it splits into two 8 gauge wires. If the wire is going to be short will 8 gauge still rob my amp (hifonics bx1500d) of power?
it depends on the length. you can pull up to 65 amps for 4-7 feet on a 8 gauge wire. i assume your 4 gauge is around 16 to 19 feet, if so you can pull up to 65 amps on the 4 gauge. (from MECP Basic Installer Book)
its always best to have a larger gauge then needed for increased power flow and future upgrades.
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