NEMA Motor Starter Size Chart: HP and Voltage Selection by Size

Jawapan Pantas: A NEMA motor starter size chart matches a starter frame, size 00 through 8, to a motor’s horsepower at a given voltage. Read the voltage column first, then shortlist the size that covers the motor’s full-load amps. Confirm coil voltage, overload range and enclosure on the exact model. The horsepower behind each size changes with voltage, so the data sheet decides. Simply Buy checks those details across brands before quoting.

This guide is for buyers, traders and maintenance teams who need to price or replace a starter, not design a panel from scratch. You will see the standard horsepower table, a four-step selection method, the difference between NEMA and IEC sizes, and the details that most often cause a wrong order. If you already have a part number, skip to the ordering checklist.

What Is a NEMA Motor Starter Size Chart?

A NEMA size is a standard frame and current class for a motor starter. It tells you how much continuous current the starter is built to carry and how its mounting and terminals are arranged. It does not tell you the horsepower by itself, because horsepower depends on voltage, phase, motor design and duty.

NEMA size is also not an enclosure type and not a certification. The size describes the starter; Type 1, Type 12 or Type 4X describes the housing it may be installed in. The size stays the same while the enclosure changes. UL listing or IEC compliance is a separate document question. The UL and NEMA motor control overview explains that boundary.

Full-load amps (FLA) is the current a motor draws at its rated load and voltage. It is the number that connects the motor to the starter.

What Horsepower Does Each NEMA Starter Size Cover?

If you are looking for a motor starter NEMA size chart, start with the table below. It is a common reference for three-phase, 60 Hz NEMA full-voltage starters. Read the voltage column first, then find the horsepower row that meets or exceeds your motor. A dash means the standard table does not list a rating; it does not mean the size cannot be supplied.

The horsepower values match the NEMA-rated starters in the Allen-Bradley industrial components catalog. Sizes above 8 are specialized and should be engineered with the manufacturer.

Size 00 is the smallest standard frame in this table; size 8 is the largest. That covers the common range used in panel and replacement work.

This table is for three-phase motors. Single-phase starters use a different selection table, so do not read these rows across.

Two examples show why the voltage column matters. A 10 HP motor needs size 1 at 460 V, but size 2 at 230 V. A 15 HP motor at 230 V sits at the top of size 2, so check FLA and service factor before accepting it.

Does a NEMA Size 2 Starter Always Mean 25 HP?

No. The 25 HP figure applies at 460 V and 575 V in the reference table. At 230 V, size 2 tops out at 15 HP; at 200 V, it tops out at 10 HP. The frame is the same, but the current at a given horsepower changes with voltage. That is why a quote that names only the size is incomplete.

Ambient temperature, altitude and the enclosure also affect the usable rating. A starter in a hot panel or a high-altitude site may need a larger frame or a manufacturer derating. The table is also a 60 Hz reference. At 50 Hz, use the 50 Hz rating or the motor nameplate FLA instead of reading a 60 Hz horsepower column as a 50 Hz rating.

How Do You Choose a Starter Size for a Motor?

Work in this order. Each step removes a different way to buy the wrong part.

Step 1: Start with motor FLA

The nameplate FLA is more reliable than a horsepower conversion. Horsepower is an output rating; FLA is the current the starter and overload must handle. If the nameplate is unreadable, use a published motor current table and mark the figure as an estimate. For a replacement, also record the original model and frame.

Step 2: Match voltage and phase

Use the actual supply voltage, not the motor’s nominal label. A dual-voltage motor wired for 230 V draws about twice the current of the same motor at 460 V, which can move the starter up one or two sizes. Confirm three-phase versus single-phase and the supply frequency.

Step 3: Choose the starter type and overload protection

Decide whether you need a direct-on-line (DOL) starter, a reversing starter, or a combination starter with a disconnect. Then select an geganti beban lampau whose setting range covers the motor FLA. Overload protection is not short-circuit protection; the branch circuit still needs fuses or a circuit breaker. The guide to calculating overload relay size walks through the setting range.

Step 4: Confirm coil, enclosure and short-circuit rating

The coil voltage is the control-circuit voltage that pulls the starter in. It is separate from the motor voltage. Confirm the enclosure type for the environment and the short-circuit current rating (SCCR) for the panel. These details live in the model suffix, not in the size. If the starter is part of a larger assembly, the motor starter contactor guide shows how the contactor, overload and enclosure fit together.

Is NEMA Size the Same as Horsepower or Enclosure Type?

No. NEMA size is a frame class; horsepower is a published rating at a voltage; enclosure type describes the housing. A supplier who quotes “size 2” without the voltage, coil and overload range has given you only part of the answer. Ask for the full catalog number and the data sheet for that number. The same size can appear in open, enclosed and combination versions, and each version has its own ordering code.

NEMA vs IEC Starter Sizes: Which Chart Do You Need?

NEMA sizes come from the North American convention and are common in replacement and plant-standard work. IEC starters are sized by AC-3 current and motor kW, and some lines use frame names such as S00, S0 and S2. A NEMA size 2 starter and an IEC starter with a 45 A AC-3 rating can both be candidates for a 15 HP, 230 V motor, but the IEC catalog expresses the rating differently and the mounting and accessories will not match.

Even within IEC, product families express the rating differently. A compact starter such as the Siemens SIRIUS 3RA6120 is selected by its current range, while a manual protector such as the ABB MS116 uses a different trip range. Both are listed in the Simply Buy catalog. Use the motor starter category to compare families, then check the exact model against your FLA and voltage.

ABB MS116‑10 Manual Motor Starter – 10A, 3‑Pole, 4kW @ 400V (AC‑3), Class 10A, 45mm Lebar

It features an adjustable thermal overload release with a setting range of 6.3…10 A and a fixed magnetic short-circuit release set at 150 A.

Lihat Butiran Produk

What Should You Check Before Ordering?

Before you send a request, collect:

• Motor nameplate: HP or kW, FLA, voltage, phase, frequency, service factor.
• Starter: NEMA size or IEC current rating, DOL, reversing or combination, coil voltage.
• Protection: overload setting range, short-circuit device, SCCR.
• Installation: enclosure type, mounting, terminal style, ambient conditions.
• Documents: data sheet, UL/CSA or IEC evidence, and the exact model code.

If you are replacing a starter, a clear photo of the nameplate and the old model is more useful than a description. The Allen-Bradley contactor replacement guide follows the same model-matching discipline.

What Else Do Buyers Ask About NEMA Starter Sizes?

Can I use a NEMA size 1 starter for a 10 HP motor? At 460 V, yes, size 1 is rated for 10 HP. At 230 V, no: size 1 tops out at 7.5 HP, so you need size 2. Always check the voltage column.

What size starter do I need for a 15 HP motor? At 460 V, size 2 covers 15 to 25 HP. At 230 V, size 2 covers 15 HP but is near its limit, so confirm FLA and service factor. At 200 V, size 2 covers 10 HP, so a 15 HP motor needs size 3.

Is NEMA size the same as NEMA enclosure type? No. Size describes the starter frame; Type 1, 12, 4 and 4X describe the enclosure. They are separate selections.

How Do You Turn the Chart into a Quote?

This size chart narrows the choice; the nameplate and the exact model data close it. Match FLA, voltage, duty, coil, overload and enclosure before you compare price. Simply Buy supplies and sources motor-control products across brands, including compact IEC starters and NEMA-rated lines, and checks the model details before quoting. Send the motor nameplate, the required size or current rating, quantity and destination to request a quote.