Current Carrying Capacity of Solid Bus Bar

Per NEC, the current rating is 1.55 Amps per sq. mm (1000 Amps per sq inch) for copper bar.

These links will also help (though the busbars here are dimensioned in inches).

http://www.husseycopper.com/production/products/bar/

http://www.copper.org/applications/busbar/ampacity/bus_table3.html

There are also many threads available in this forum on the same topic, please search.

- MS

msamad,thanks for your post.

As you said ,according to NEC the current rating is 1000 Amps per sq inch,so at 500A the area should be 1/2 sq inch.

But the tables you referred to show for 500A the area should be only 1/4 sq inch.

Why that difference?

The difference is because of

The current ratings mentioned in the links are most probably considered in open air but the NEC mentioned the current ratings of the copper bars in the sheet metal gutters. See the NEC quote

"The current carried continuously in bare copper bars in sheet metal auxiliary gutters shall not exceed 1.55 amperes/mm² (1000 amperes/in.2) of cross section of the conductor. For aluminum bars, the current carried continuously shall not exceed 1.09 amperes/mm2 (700 amperes/in²) of cross section of the conductor."

- MS

The above post (#6) has been submitted without the login and posted by Guest. I had to restart (hard stop) my laptop after it was frozen and somehow the cookie was lost.

- MS

I= (7.7 *(A^(0.5))*(P^(0.39))))

for an ambient temp of 40-50c

where

A - Cross sectional area of conductor in sq.mm

P - Perimeter of conductor in mm.

Is this formula for AC or DC current ?

Good question.

both

http://cr4.globalspec.com/search/sitesearch?do=show&sort=textmatchrank&srch=busbar%20sizing&order=asc

You should know the quality(conductivity) and emissivity of material and refer manufacturer's literature