Electrical reference chart
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.
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
| 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
| 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 |
How to use this chart
Start with motor nameplate data
Record HP, voltage, phase, FLA, service factor, duty, enclosure, control voltage, and starter type before selecting a starter rating.
Separate starter and protection
Starter size, overload range, short-circuit protection, conductor ampacity, and starting behavior are related but not the same selection.
Use the calculator as a record
Open the motor starter calculator when starter rating, overload range, branch protection, enclosure, and manufacturer notes must stay together.
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 screen
Before 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 starts
A pump with frequent starts needs duty, overload setting, starter type, enclosure, and branch protection reviewed together instead of selecting a starter from HP alone.
Related calculators
NEMA Starter Sizing Calculator
Select NEMA motor starter size based on motor HP and voltage per NEMA ICS 2
Motor Branch Circuit Protection Calculator
Screen NEC Article 430 motor branch-circuit short-circuit and ground-fault protective device sizing from motor FLC, motor type, and device type.
Full Load Current Calculator
NEC Table 430.248/430.250 motor full load current (FLC) lookup with conductor sizing, overload-basis reminder, and branch-circuit breaker requirements
Related charts
Motor Full Load Amps Chart
Plan motor full-load amp work by separating table FLC, nameplate FLA, formula estimates, starting current, overloads, and branch-circuit protection.
Breaker Size Chart
Plan breaker size from load category, continuous duty, conductor protection, interrupting rating, equipment listing, and calculator result notes.
HP to Amps Chart
Use this HP to amps chart: 10 HP at 480V 3-phase estimates 11.2A running current; compare nameplate FLA and NEC FLC before sizing.
Frequently asked questions
These answers explain how to use the chart without turning a quick reference into a final design decision.