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Motor branch circuit playbook

Goal​

Size a motor branch circuit using motor-specific conductor and protection rules with clear documentation for inspection.

Inputs you must know before you start​

  • Motor type, rating, and control method.
  • Installation conditions and conductor routing.
  • Available standard OCPD ratings and equipment terminations.
  • Grounding and bonding method.

The path (in order)​

  1. Determine the correct motor current for sizing.
  2. Size conductors using motor conductor rules.
  3. Select OCPD using motor short-circuit protection allowances.
  4. Provide overload protection where required.
  5. Verify grounding and bonding conductors.
  6. Document assumptions and settings.

This is​

A structured sizing path for motor branch circuits that separates overload protection from short-circuit protection.

This is not​

A complete motor control design or coordination study.

Inspection-ready checklist​

  • Motor current value documented and verified.
  • Conductor size based on motor rules.
  • OCPD rating aligned with motor allowances.
  • Overload protection installed or set.
  • Grounding and bonding confirmed.

Worked example​

A motor branch circuit is sized from the motor current table, conductors are selected accordingly, and a larger OCPD is chosen under motor allowances while a dedicated overload device handles motor protection.

Cross references​

  • Primary: 430
  • Secondary: 240, 310, 110.14(C), 250

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