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Joining Copper Busbars by welding or brazing
March 21, 2014
Q. Good morning,
We are dealing with copper busbars of 1250 amp, "T" off it with a smaller busbar say 200 amp. We are currently bolting it onto each other but want to change from bolts to, for example, "Welding or Brazing" instead of bolts. What is the best and most reliable method to ensure the "T" joint is good and will not become an immediate or eventual "HOT SPOT"
Look forward to your reply
Electrical Engineering - South Africa
A. Hi Chris. Electrolytic copper has very high conductivity, whereas even a small amount of contaminant (anything not electrolytically pure) dramatically reduces the conductivity. As a result, each of the connections you've shown us is going to be a hot spot because you're trying to carry the electricity through a cross section of the same size but much greater resistivity.
I think what needs to be done, and you probably won't like it, is to make the connection the same way you would for a bolted joint, i.e., with copper bar overlapping copper bar for a large cross-sectional area across the joint so the reduced conductivity is not an issue. Then I think brazing will be fine.
Ted Mooney, P.E.
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