To create a motor control center, go to
Ribbon: DM Electrical->Distribution Equipment-> 
Motor Control Centers
Pulldown Menu: DM Electrical->Distribution Equipment->Motor Control Centers
Motor Control Center Dialog Box
See the Common Schedule Dialog Box Features section for more information about how this dialog box works. This section describes the Rename, Find, Previous, Next, New, Copy, Save, and Delete buttons.
Horizontal Bus Amps: The size of the horizontal bus, in amps, feeding the vertical buses.
Number of Sections: The number of sections in the motor control center.
Section Height: The height of each motor control center section, in inches.
See the Distribution Equipment Dialog Box Settings section for more information about the other values and buttons in this dialog box.