1HP Sump Pump Circuit

Size conductors, breakers, and overload protection for safe motor operation.

1Motor Specifications

Voltage

Phase

NEC Table (FLC) vs. Nameplate (FLA)

Per NEC 430.6, you must use the values from the NEC Tables to size your wire and breakers. The "Nameplate FLA" from the motor's sticker is only used for sizing the Overload protection.

2Protection & Overload

Device Type

Service Factor

Nameplate FLA

The actual current listed on the motor sticker. This is used for precise Overload (Heater) sizing only.

Calculation Summary
Based on NEC Table 430.248 (Single-Phase) or Table 430.250 (Three-Phase). The FLC is used to size branch circuit conductors and short-circuit protection.

-Amps

NEC 430.250

Breaker

Short Circuit Protection

15 Amps

Max 250% of FLC (NEC 430.52). Rounded up to next standard size.

Wire Size

Branch Circuit

14 AWG

Min 125% of FLC (2.6A). Based on 75°C column.

NEMA Starter

Motor Controller

N/A

Standard NEMA size for 1 HP @ 460.

Overload

Heater Setting

2.6 Amps

125% of Table FLC.

Popular motor control Configurations

1HP 115V Single Phase Motor Calc 10HP 460V 3-Phase Motor Calc 5HP Air Compressor Circuit Size 1HP Sump Pump Circuit

Motor Sizing Formula

I_branch = 1.25 × Total FLC
I_overload = I_nameplate × Service Factor

NEC Article 430

Article 430 covers motors. Table 430.248 (1-phase) and 430.250 (3-phase) provide FLC currents. 430.52 dictates maximum short-circuit and ground-fault protection settings.

Frequently Asked Questions

Do I use nameplate amps or NEC table amps?

For sizing conductors and short-circuit protection (breakers/fuses), you MUST use NEC Table values. For sizing Overload protection (heaters), you use the Nameplate current.

What size breaker do I need for a motor?

Inverse time breakers are typically allowed up to 250% of the motor's FLC per Table 430.52 to handle inrush current without nuisance tripping.

What size wire do I need for a motor?

Conductors supplying a single motor must have an ampacity of at least 125% of the motor's FLC Rating (NEC 430.22).

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1HP Sump Pump Circuit

Understanding Motor Calculations

1Motor Specifications

2Protection & Overload

Calculation Summary
Based on NEC Table 430.248 (Single-Phase) or Table 430.250 (Three-Phase). The FLC is used to size branch circuit conductors and short-circuit protection.

Breaker

Wire Size

NEMA Starter

Overload

Popular motor control Configurations

Motor Sizing Formula

NEC Article 430

Frequently Asked Questions

Do I use nameplate amps or NEC table amps?

What size breaker do I need for a motor?

What size wire do I need for a motor?

1HP Sump Pump Circuit

Understanding Motor Calculations

1Motor Specifications

2Protection & Overload

Calculation Summary
Based on NEC Table 430.248 (Single-Phase) or Table 430.250 (Three-Phase). The FLC is used to size branch circuit conductors and short-circuit protection.

Breaker

Wire Size

NEMA Starter

Overload

Popular motor control Configurations

Motor Sizing Formula

NEC Article 430

Frequently Asked Questions

Do I use nameplate amps or NEC table amps?

What size breaker do I need for a motor?

What size wire do I need for a motor?

1HP Sump Pump Circuit

Understanding Motor Calculations

1Motor Specifications

2Protection & Overload

Full Load Current (FLC)Calculation SummaryBased on NEC Table 430.248 (Single-Phase) or Table 430.250 (Three-Phase). The FLC is used to size branch circuit conductors and short-circuit protection.

Breaker

Wire Size

NEMA Starter

Overload

Popular motor control Configurations

Motor Sizing Formula

NEC Article 430

Frequently Asked Questions

Do I use nameplate amps or NEC table amps?

What size breaker do I need for a motor?

What size wire do I need for a motor?

1HP Sump Pump Circuit

Understanding Motor Calculations

1Motor Specifications

2Protection & Overload

Full Load Current (FLC)Calculation SummaryBased on NEC Table 430.248 (Single-Phase) or Table 430.250 (Three-Phase). The FLC is used to size branch circuit conductors and short-circuit protection.

Breaker

Wire Size

NEMA Starter

Overload

Popular motor control Configurations

Motor Sizing Formula

NEC Article 430

Frequently Asked Questions

Do I use nameplate amps or NEC table amps?

What size breaker do I need for a motor?

What size wire do I need for a motor?

Calculation Summary
Based on NEC Table 430.248 (Single-Phase) or Table 430.250 (Three-Phase). The FLC is used to size branch circuit conductors and short-circuit protection.

Calculation Summary
Based on NEC Table 430.248 (Single-Phase) or Table 430.250 (Three-Phase). The FLC is used to size branch circuit conductors and short-circuit protection.