Recently I was reviewing some of the material in the ABYC Electrical Certification study guide and came across a table that we use when teaching that class to electrical technicians. The table I’m referring to compares the conductivity of metals both thermally and electrically. What made me think of all of this was something I saw in an accessory catalogue I was perusing this past Memorial Day weekend that showed some brass terminal “expanders” for battery terminals. The bottom line is that brass is only about 25% as electrically conductive as copper. Then, as I was flipping through part of my photo library, I ran across this photo on an on-board electrical system on someone’s boat. Check out the brass buss bar. Nothing like consciously creating an inherent weak point right at the main power distribution panel. The bottom line here? Use only copper buss bars. Preferably tinned copper buss bars like the units my friends at Blue Sea and BRP sell. Why start out with excessive electrical resistance?