Sump Pump & Well Pump Surge Sizing Calculator
Basement flood prevention, emergency power sizing. Computes continuous running watts and inductive motor starting surge for 1/3 HP, 1/2 HP, 3/4 HP, and 1 HP sump and submersible well pumps.
Step-by-Step Derivation ▼ Show Steps
Calculations adhere to standard electrical engineering physics and National Electrical Code (NFPA 70) regulations.
Engineering Principles & Calculations
This calculator uses the exact mathematical relationships between Pump Horsepower (1/3, 1/2, 3/4, 1, 1.5 HP), Voltage (120V or 240V) to determine Running Current (A), Running Watts, Starting Surge Watts, Minimum Generator / Battery Backup Size. In practical installations, factors such as ambient raceway temperature, harmonic distortion, duty cycle continuous operation, and conductor impedance must be accounted for by a certified electrician.
Computes continuous running watts and inductive motor starting surge for 1/3 HP, 1/2 HP, 3/4 HP, and 1 HP sump and submersible well pumps.
Typical Application & Industry Guidelines
Basement flood prevention, emergency power sizing.
Sump Pump & Well Pump Surge Sizing Calculator Benchmark Lookup Table
| Pump Size | Running Watts @ 120V | Starting Surge Watts | Min Generator Size |
|---|---|---|---|
| 1/3 HP Sump Pump | 650 Watts (5.4A) | 1,800 Watts (15.0A) | 2,000 Watts |
| 1/2 HP Sump Pump | 900 Watts (7.5A) | 2,500 Watts (20.8A) | 3,000 Watts |
| 3/4 HP Sump / Well Pump | 1,300 Watts (10.8A) | 3,800 Watts (31.7A) | 4,500 Watts |
| 1.0 HP Deep Well Pump | 1,600 Watts (13.3A) | 4,800 Watts (40.0A) | 5,500 Watts |
| 1.5 HP Well Pump (240V) | 2,100 Watts (8.8A @ 240V) | 6,500 Watts (27.1A @ 240V) | 7,500 Watts |