There is no one detailed procedure for this; it depends on any of the several basic approaches to building an MCC, and on the manufacturer of the components.
Even then, a detailed procedure would amount to a book, which is impractical to give in a few forum posts.
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Asking Anonymous Poster #1 would be the first step in any procedure, as it is far easier to clone what has been done before rather than start with a blank piece of paper.
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An
MDB will require more in layout considerations than a PLC or an MCC panel.
Commonly
you begin with completing your wiring diagram (your design), then your
materials list. After you have all the required components with their data
sheets, you arrange your panel with respect to your components dimensions,
finish your layout, final check, and send for fabrication.
You
can download starters' catalogue from manufacturers' website to look up
products by reference with respect to motors rating.
It
will be a little off hand calculation because not all ratings are readily
available in the market, and in that case, you will be pointed for a next step
up.