Which type of boat bus bars are the best: copper or brass? It's a common question with a very simple answer: copper.
A copper bus bar is slightly better than a brass bus bar for one simple reason: the sole purpose of a bus bar is to conduct electricity, and copper is a better material at doing that than any other metal, except silver. Copper is one of the most conductive metals found on the planet, and it's better at conducting electricity and heat than brass.
Nothing Wrong with the Brass
Although copper has been established as the victor here, it's unlikely you'll notice any difference between a copper or brass bus bar, because the performance of a brass bus bar is only marginally lower than that of a copper busbar. In fact, the performance differential barely even registers, and is probably only about 0.02% or less.
What we're saying here is that brass busbars need not be condemned for their slight shortcomings when compared to their copper counterparts. In other words, if you already have brass bus bars on your boat, there's no need to replace them with copper busbars because you probably won't notice the difference.
Copper Wins
Copper bus bars are better at conducting electrical currents, but that performance advantage is really not enough to put a championship belt on copper for its victory in the "Copper vs Brass: Battle of the Bus Bars" debate. The fact is any quality-brand bus bar — brass or otherwise — should perform just as well as its copper counterpart. Choose a good quality bus bar from a trusted manufacturer and it won't let you down, period. If you ever do get into a discussion about which type is better, just say copper. Source : https://www.boats.net