Calculating the ampacity of copper and aluminum busbars has never been easier.
Busbars are used in switchboards, load centers, and panelboards. Busbars are generally uninsulated. The constant amperage for a bare copper wire (Cu) busbar must not exceed 1000 A sq in. of the cross-sectional area of its bar.
Aluminum (Al) busbars may not endure constant amperage exceeding 700 A sq in. of the cross-sectional area of the bar per 366.23 (A). To calculate the ampacity of a busbar, apply the following equation.
Busbar ampacity= T x W x constant, where busbar ampacity = ampacity of busbar (in A)
f = thickness (in in.)
w = width (in in.)
constant 1000 for Cu and 700 for Al
What is the ampacity of a ¼” thick by 3″ wide Cu busbar?
Busbar ampacity= T x W x Constant
Busbar ampacity 0.25” x 3” x 1000
Busbar ampacity=0.75 x 1000
Busbar ampacity 750 A
What is the ampacity of a ½” thick by 2” wide Al busbar?
Busbar ampacity=T x W x Constant
Busbar ampacity 0.50” x 2” × 700
Busbar ampacity= 1x 700
Busbar ampacity= 700 A