When it comes to electrical control systems, motor starter sizing is one of the most critical decisions you can make. Whether you're installing a small fractional horsepower motor or powering a high-horsepower industrial pump, getting the motor starter sizing right ensures safety, performance, and long-term reliability.
At National Motor Starters, a division of Palmer DCS, we’ve been building enclosed magnetic starters for over 50 years. We bring unmatched expertise and quality to the electrical control marketplace—and today, we’re here to help you understand the essentials of motor starter sizing.
What Is Motor Starter Sizing?
Motor starter sizing refers to selecting the correct motor starter for a specific electric motor based on its voltage, current draw, and application. Starters are essential components that safely start, stop, and protect electric motors. An undersized starter can fail prematurely or even cause damage. An oversized starter may lead to unnecessary costs or reduced performance.
That’s why accurate motor starter sizing is key to operational success.
Why Motor Starter Sizing Matters
Choosing the correct motor starter isn’t just about matching numbers. The proper motor starter sizing supports:
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Protection: Prevents motor overloads and protects both the motor and connected systems.
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Efficiency: Ensures consistent operation and minimizes wear and tear.
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Longevity: Reduces the risk of early starter or motor failure.
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Compliance: Meets UL standards and ensures your system is up to code.
At National Motor Starters, every unit we produce goes through a rigorous quality assurance checklist to verify sizing, performance, and safety. We don’t just ship products, we deliver peace of mind with every starter.
How to Determine the Right Motor Starter Size
Correct motor starter sizing involves several factors:
1. Motor Horsepower and Voltage
The horsepower (HP) and voltage rating of the motor determine the baseline sizing requirements. We offer starters for ½ to 100 HP, and for 208, 230, or 460 volts, in both single- and three-phase configurations.
2. Full Load Amps (FLA)
FLA is the current the motor draws at full load. It’s essential for choosing the right overload protection. Starter contactors and overload relays must be rated for the motor’s FLA.
3. Service Factor and Duty Cycle
Some motors run continuously, while others are intermittent. These details affect motor starter sizing and the type of overload protection needed.
4. Application Environment
Will the starter be exposed to dust, moisture, or high heat? National Motor Starters builds to UL standards and offers NEMA enclosures tailored to your site conditions.
Our Advantage in Motor Starter Sizing
When you work with National Motor Starters, you’re not just getting a product—you’re getting a team with over five decades of manufacturing experience. Here’s what sets us apart:
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All starters include Schneider Electric contactors and overloads
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Color-coded wiring for traceability and ease of troubleshooting
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Same-day or next-day shipping through our “built to order” quick-ship program
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Online configuration tools for custom starter builds
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IEC and NEMA starter options available
Every product we ship is tested and verified for proper motor starter sizing, reliability, and compliance.
Built on Quality, Driven by Values
At National Motor Starters, our mission is to deliver high-quality, flexible, and reliable motor control solutions. As a division of Palmer DCS, we draw on a legacy of innovation and accountability. Our motto: “To be the best damn little company!”
From remanufactured warehouse upgrades to streamlined workflows, we’re constantly improving to meet and exceed client expectations. Motor starter sizing is just one of the many areas where our deep expertise delivers real value.
Your Partner in Motor Starter Sizing
With more than 50 years in the industry, National Motor Starters is a trusted name in motor starter sizing and custom motor control solutions. Our team doesn’t just meet specifications—we solve problems.
Whether you're designing a new system, replacing outdated equipment, or troubleshooting sizing concerns, you can count on us to deliver the right starter, every time.
Ready to get started? Contact National Motor Starters today and let our experts help you with accurate, reliable, and efficient motor starter sizing.