Motor circuits wrapper
Why you care (60 seconds)
Motor circuits use different sizing rules than standard loads. If you size them like a typical branch circuit, you will likely fail inspection or cause nuisance trips.
Where people lose time
- Using nameplate amps without checking motor tables where required.
- Applying standard OCPD sizing without motor allowances.
- Mixing up overload protection with short-circuit protection.
This is
The rule in plain language
Motor conductors and overcurrent protection are sized using motor-specific rules that account for starting current and required overload protection.
When it applies
Any time you size conductors or protection for a motor-driven load.
What you must do (checklist)
- Use the correct motor current value for sizing.
- Size conductors using motor conductor rules.
- Select OCPD based on motor protection allowances.
- Provide overload protection where required.
Quick examples
- A motor branch circuit may allow a larger breaker than a standard load.
- Overload protection is separate from short-circuit protection.
This is not
Common misreads
- Treating motor circuits like general-purpose branch circuits.
- Assuming the breaker rating provides overload protection.
What it doesn't cover
- Detailed motor control wiring.
- Special rules for specific motor types or drives.
False friends
- A nameplate value is not always the sizing current.
Exceptions & edge cases
- Certain motor types have dedicated sizing rules.
- Adjustable-speed drives can change protection requirements.
Cross-references (NEC map)
- Primary: 430.22, 430.52
- Secondary: 430.32
Exam traps
- Using the wrong current value for sizing.
- Missing the distinction between overload and short-circuit protection.
Field notes
- Keep a motor sizing worksheet in the job file.
- Verify motor controller and overload device settings during commissioning.
AHJ / Local amendments notes (placeholder)
- Add local amendments or interpretations here.
Revision notes
- Draft wrapper created for motor circuit fundamentals.