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Sizing Equipment Circuits using MCA and MOCP

This tutorial teaches you how to size equipment circuit breakers and wires using MCA and MOCP.

Open drawing E-2.1,2.

Create and Circuit Equipment​

  1. Run the Create Equipment command. The Create Equipment dialog box will open.
    Ribbon: DM Electrical→Devices→  Create Equipment
    Pulldown Menu: DM Electrical→Equipment→Create Equipment

  2. Set Equipment Callout to AHU.

  3. Set Volts ▾ to 480V 3P 4W.

  4. Set Load 1 Horsepower ▾ to 40.

  5. Press the button.

  6. Follow the prompts at the command line to insert the equipment connection and callout on the drawing.

  7. Run the Circuiting command. The Circuiting dialog box will open.
    Ribbon: DM Electrical→Circuit and Homeruns→  Circuiting
    Pulldown Menu: DM Electrical→Circuit and Homeruns→Circuiting

  8. Set Distribution Equipment ▾ to H1.

  9. Select a circuit that is currently a space.

  10. Press the button.

  11. Select equipment AHU to circuit it.

  12. Press ENTER twice to return to the Circuiting dialog box.

Note that the breaker is set to 70A and the wire size is set to #4.

  1. Press the button.

Size Equipment Using MCA and MOCP​

  1. Run the Query Device command.
    Ribbon: DM Electrical→Devices→  Query Device
    Pulldown Menu: DM Electrical→Modify Devices→Query Device

  2. Select equipment AHU. The Edit Equipment dialog box will open.

  3. Set MCA to 100 and MOCP to 40.

    note

    Breaker Size ▾ and Wire Size ▾ use the MCA and MOCP you set to size the breaker and wire for the equipment. There are other options available for sizing that correspond to other sections in the NEC.

  4. Press the button to close the dialog box.

  5. Run the Circuiting command. The Circuiting dialog box will open.
    Ribbon: DM Electrical→Circuit and Homeruns→  Circuiting
    Pulldown Menu: DM Electrical→Circuit and Homeruns→Circuiting

Note that the breaker size is now 40A and the wire size is now #1.