Motor Starter Size Chart

Use this motor starter size chart after the calculator result to document HP, voltage, phase, current source, starter type, overload range, enclosure, and branch protection before ordering or replacing a starter.

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Quick reference table

Motor starter sizing is a motor-control worksheet, not horsepower alone. Use the calculator with motor HP, voltage, phase, table FLC, nameplate FLA, overload range, starter type, enclosure, duty, control voltage, branch protection, manufacturer ratings, adopted NEC requirements, and AHJ review.

Motor starter worksheet inputs

Motor starter worksheet inputs
Input	Record	Why it matters
Motor data	HP, voltage, phase, duty, service factor, nameplate FLA	Sets starter family and overload context
Current source	Table FLC, nameplate FLA, or drive current	Keeps branch protection and overload decisions separate
Starter type	NEMA starter, listed controller, soft starter, or VFD input	Changes equipment selection and manufacturer instructions
Overload range	Heater size, electronic setting, class, and reset method	Protects the motor running condition
Environment	Enclosure rating, ambient heat, washdown, dust, and duty	Controls equipment suitability in the field

After the starter calculator result

After the starter calculator result
Result item	Field follow-up	Why it matters
Starter size selected	Check motor nameplate, duty, and voltage class	A catalog size still needs application match
Overload range fits	Set value, service factor basis, and reset mode	Overload protection is not the same as short-circuit protection
Branch OCPD selected	Review starting current, conductor size, and equipment instructions	Nuisance trips and protection gaps can both occur
VFD or soft starter used	Follow the drive or starter manual for input and output protection	Standard starter assumptions may not apply

Formula basis

Starter planning screen = motor HP and voltage class plus the correct FLC or nameplate current source, then compare starter rating, overload range, enclosure, and protection path.

Motor HP, voltage, and phase identify the starter rating family.
Table FLC and nameplate FLA can support different parts of conductor, overload, and protection review.
Starter type, enclosure, control voltage, duty, and manufacturer rating must match the application.

Worked examples

Starter replacement screenBefore replacing a starter, document the motor nameplate, existing overload range, enclosure type, control voltage, short-circuit protection, and reason for failure.

Pump motor with frequent startsA pump with frequent starts needs duty, overload setting, starter type, enclosure, and branch protection reviewed together instead of selecting a starter from HP alone.

Assumptions. Balanced load and line-to-line voltage assumptions behind this chart.

This chart is a planning worksheet and does not reproduce manufacturer starter sizing tables.
Starter selection can depend on application duty, enclosure, overload device, control voltage, starter type, short-circuit rating, and equipment listing.
VFD and soft-starter applications should follow the specific manufacturer manual rather than a generic starter-size shortcut.

Code and standard notes. Planning limits that should be checked before final equipment selection.

Verify the adopted NEC edition, motor nameplate, starter manufacturer data, equipment listing, local amendments, and the Authority Having Jurisdiction (AHJ) before final installation decisions.
Verify motor nameplate data, overload protection, branch-circuit short-circuit protection, starter listing, SCCR, enclosure rating, and manufacturer instructions before final selection.

How to use this chart

1Start with motor nameplate dataRecord HP, voltage, phase, FLA, service factor, duty, enclosure, control voltage, and starter type before selecting a starter rating.

2Separate starter and protectionStarter size, overload range, short-circuit protection, conductor ampacity, and starting behavior are related but not the same selection.

3Use the calculator as a recordOpen the motor starter calculator when starter rating, overload range, branch protection, enclosure, and manufacturer notes must stay together.

Worksheet checklist. Record source basis, review gaps, and assumptions before using the chart result.

Record motor and starter dataWrite HP, voltage, phase, nameplate FLA, service factor, control voltage, starter type, enclosure rating, and duty cycle.
Document overload settingIdentify overload device type, setting range, trip class, reset method, service factor basis, and manufacturer adjustment instructions.
Review starting behaviorCheck across-the-line, reduced-voltage, soft-start, or drive operation before final branch protection and conductor choices.

Common mistakes to avoid. Review these before turning chart current into an equipment decision.

Selecting a starter only from HP while ignoring voltage, phase, nameplate current, enclosure, overload range, control voltage, and duty.
Treating overload protection and branch-circuit short-circuit protection as the same setting.
Replacing a failed starter without documenting the motor nameplate, failure mode, enclosure environment, and manufacturer compatibility.

Frequently asked questions

These answers explain how to use the chart without turning a quick reference into a final design decision.

Can I size a starter from horsepower only?

No. Horsepower is a starting point, but voltage, phase, nameplate current, overload range, enclosure, control voltage, and duty also matter.

Is a VFD output the same as a standard starter?

No. Adjustable-speed drive applications should follow drive manufacturer instructions and the specific input and output protection path for the installation.

Why separate overload and branch protection?

Overloads protect the motor during running conditions. Branch-circuit protection addresses short-circuit and ground-fault conditions, so the settings should not be collapsed into one number.