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Busbar selection table. 2020-11-07

Just John
First release
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4.00 star(s) 3 ratings

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CM is not centimeters! It's "Circular Mills" 1" square is equal to 1,273,237 Circular Mills. The ampacity tables I've been looking at list the cross section area in CM (thousands). Multiply the listed number by 1000 and you get the full number.

A 1/4" x 1" bus bar is 318.3 circular mills (thousands). Actual circular mills is 318,300 (318.3 x 1000). 318300 / 1273237 = .25, or 1/4".

Here's another bus bar ampacity table. The benefit for this table is that it has aluminum and copper side-by-side. Note that the table is for 6101-T6 not 6061-T6.
I found this really helpful but I do have a question: What does it mean by "cross-section area"? It doesn't seem to be a reference to the bar's cross section...or at least a bar that's 1/2" wide and 1/8" thick does not have a cross section of 79.6 cm (squared? it doesn't say). Should I just be ignoring the whole "cross-section area" part of it?
Just John
To be honest I have no clue what the cross section area part means. I just ordered what I needed from McMaster-Carr.
Thanks for starting this busbar info resource - I'm constantly re-checking what's the best material.

Note: The chart that comes up is for AC current applications. The DC busbar chart page is here:
Just John
Yes, thanks for pointing that out. I updated it. I've actually got three different links in there, but default should be DC now.