I'm working on redesigning a bus bar system inside a metal enclosure. The bus bars are currently 1/4" x 3" which, according to copper.org, gives an ampacity of at most 1550. Someone had the idea to "double" the ampacity by simply bolting a second identical bar to the first but this won't work since the ampacity is based more on surface area and heat transfer than on the volume of copper present. The question I'm trying to find an answer for now is: Is there any kind of derate factors or other technical information about the effects of using multiple bus bars arranged with an air gap? How large does the space between them have to be before the ampacity of a two 1/4"x3" bus bars is equal to two times the ampacity of a single?
From what I've seen, there seem to be two methods for calculating ampacity.
1. Look at the tables on copper.org.
2. Assume 1.2 A per square mm.
The latter method doesn't account for any type of heat dissipation and actually varies significantly from the first at both high and low ampacities. The first only works with single bus bars. I've seen a few references out there to research that has been done but I think it was for aluminum.
Any help is much appreciated.
From what I've seen, there seem to be two methods for calculating ampacity.
1. Look at the tables on copper.org.
2. Assume 1.2 A per square mm.
The latter method doesn't account for any type of heat dissipation and actually varies significantly from the first at both high and low ampacities. The first only works with single bus bars. I've seen a few references out there to research that has been done but I think it was for aluminum.
Any help is much appreciated.
