Brass vs. Copper Buss Bars for Electrical Distribution

Brass isn't nearly as good a conductor as copper, but it can work as long as the distances from individual terminals to the battery cable are short.

2nd October 2013.
By Ed Sherman

Question: A friend and I have a bet. I sent in a photo of one of the electrical buss bars on his new boat. It is the DC (12-volt) negative buss bar for all of his battery-powered electrical equipment on the boat. You can clearly see from the photo that the bar is a bright yellow color typical for brass, not copper, which is typically more pink in color.

The shiny yellow buss bar is likely made of brass, not copper. The heavy cable on the left handles the negative side of the circuit.

The shiny yellow buss bar is likely made of brass, not copper. The heavy cable on the left handles the negative side of the circuit.

I’m telling him this might be a problem because brass is not a very good conductor of electricity when compared to copper. He says that he’s not too worried about it as everything on the boat works just fine. Is this brass buss bar a potential problem?

Answer: Excellent question! The truth is you may have to split the bet evenly. You are quite correct that brass is not as good a conductor of electricity as copper. In fact, brass is only about 25-percent as conductive as copper. So, with that knowledge in hand you might expect this buss bar to be a major problem for the electrical circuits tied to the bar. The reason it may not be is that the actual distance between the individual small-gauge wires and the rather large-gauge (yellow) cable that connects all of the small wires to the battery(s) on the boat is really rather short. It’s hard for me to say with precision, but I’ll bet the actual measurable voltage drop across that buss bar isn’t that much, due to the relatively short distance involved here.

All that said, copper buss bars are a much better choice for this application. So, fight it out as to who buys the next round.


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About the author:

Ed Sherman

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Ed Sherman is a regular contributor to boats.com, as well as to Professional Boatbuilder and Cruising World, where he previously was electronics editor. He also is the curriculum director for the American Boat and Yacht Council. Previously, Ed was chairman of the Marine Technology Department at the New England Institute of Technology. Ed’s blog posts appear courtesy of his website, EdsBoatTips.
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http://www.EdsBoatTips.com

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