Well Pump Starting Watts

Well pump watts, amps, and starting demand by horsepower

These ranges come only from the exact manufacturer tables on this page. They are useful published examples, not universal wattage or current ratings for every pump of the same horsepower. Voltage, motor family, wire arrangement, and control type still matter.

On a small screen, scroll this table sideways to see every column.

Approximate starting VA is calculated as source voltage × published LRA. It is not manufacturer-published real watts. Watt ranges use only the Franklin and Goulds/Xylem rows that publish real input watts and include the published full-load and maximum service-factor conditions. Pentek rows do not publish input watts; unpublished does not mean zero. Match the detailed row before using a watt value.

How many running watts does a well pump use?

In the manufacturer rows below, published real-input examples across the full-load and maximum service-factor conditions range from 655–960 W for 1/2 HP, 925–1,400 W for 3/4 HP, 1,130–1,600 W for 1 HP, 1,620–2,280 W for 1.5 HP, and 2,025–2,555 W for 2 HP. These are examples from the exact Franklin and Goulds/Xylem records, not universal horsepower ratings.

When a manufacturer publishes watts directly, that number is the best wattage reference for the stated load condition. Published real watts are watts. Volts × amps is apparent power in VA, so SizeMyGenerator does not infer real watts from current or use a guessed power factor. The Pentek sources used here do not publish real input watts, so no Pentek watt values are calculated.

How many amps does a well pump draw?

Homeowners commonly find two different amp values. For running current, SizeMyGenerator prefers the manufacturer’s Max S.F., SFA, or maximum service-factor current when published. If it is unavailable, use FLA or Full Load Amps.

For starting current on a conventional fixed-speed pump, use the published LRA when available. Running amps describe the pump after it is up to speed. LRA describes the brief starting demand. They answer different questions.

Running current vs. starting current

Running current is what the pump needs after it is up to speed. Starting current is the brief higher demand while the motor starts.

The pump’s running current contributes to normal household demand. Its starting current is checked separately against the generator’s temporary surge capability.

A 3/4 HP well-pump example

Franklin prefix 244507 is a 3/4 HP, 230 V, 2-wire motor. Its source table publishes 6.8 A and 940 W at full load, 8.0 A and 1,310 W at maximum service-factor load, and 40.7 A LRA.

The generator calculator combines those pump values with the other loads in the home.

How to find your pump information safely

Check these sources in order. The first few often have everything you need:

1. installation or service records;
2. the pump invoice or equipment schedule;
3. the owner’s manual or exact manufacturer documentation;
4. an accessible control-box or drive label;
5. the pump installer or service company; and
6. a qualified measurement when the published value cannot be found.

Photograph or write down the complete label and keep each current-field name with its value. Do not pull a submerged pump, disturb the well cap, or open energized equipment just to collect data.

Official well-pump manufacturer electrical data

Use these tables to identify the exact motor and control combination. Each row keeps the source voltage and LRA visible, and the approximate starting VA column transparently multiplies those two values. Published real input watts appear only where the cited manufacturer data supplies them.

Do not choose a row just because the horsepower matches your pump. Values can change with the manufacturer, motor family or model, voltage, 2-wire or 3-wire architecture, and control type. The Franklin/Pentek comparison at the top of this page shows how large that difference can be.

These tables are reference aids, not calculator lookup data. You confirm which row applies and manually enter its voltage, running amps, and starting amps in the generator sizing calculator. Nothing is transferred automatically.

What numbers do I need for the generator calculator?

You confirm the exact equipment values and enter them manually. The page does not select a model or transfer a table row into the calculator.

Open the generator sizing calculator

What size generator will run my well pump?

The pump’s running load is one part of the normal household load. The generator must also have enough temporary surge capability to start the pump. Other loads that may be running at the same time still count.

SizeMyGenerator includes the pump’s running contribution in normal demand, checks the pump start separately, and accounts for the other household loads you select. Bring the three exact pump values above rather than choosing a generator from horsepower alone.

Size the pump with the rest of the home

2-wire vs. 3-wire well pumps

Wire count helps identify the correct motor and control combination. It isn’t a generator-size conversion. The manufacturer table above shows that 2-wire and 3-wire equipment can have different running currents, LRAs, and minimum-generator guidance.

Variable-speed and constant-pressure pumps

A drive-based system can control acceleration differently from a conventional fixed-speed motor. Don’t apply the fixed-speed table above to Franklin SubDrive/MonoDrive, Grundfos SQ/SQE, or another variable-speed or constant-pressure system unless the exact manufacturer documentation says to use that method.

Find the controller model and follow its generator-sizing instructions. The drive, motor, generator waveform and regulation, voltage and frequency response, and other running loads still matter.

What if I can’t find the starting amps?

Don’t guess from horsepower alone. Keep the voltage and running information you can verify, then look for the starting-current value in:

• the manufacturer manual or exact motor table;
• the control-box or drive information;
• installation or service records; or
• a clearly defined measurement from a qualified pump or electrical professional.

Without adequate starting-current data, the calculator can show the running-load information you entered, but it won’t give a final generator-class result that depends on the missing peak check.

Manufacturer minimum-generator ratings

A published minimum generator rating is separate application guidance for the exact pump, motor, and control setup. It isn’t running load, starting VA, an extra amount to add to the house, or a complete whole-home recommendation.

The four values below come from the Franklin and Goulds/Xylem sources linked in the table. No Pentair/Pentek minimum is shown because the Pentair sources used here do not publish a conventional minimum-generator table.

On a small screen, scroll this table sideways to see every column.

A generator still needs enough capacity for the home’s running demand and the pump-start event. It must also meet the pump and generator manufacturers’ requirements for the exact equipment and installation.

Well pump watts, amps, and generator FAQs

Keep planning

• Home Generator Sizing Guide
• Well and Sump Pump FAQs
• Technical and Electrical FAQs
• Portable Generator FAQs
• Transfer Switch vs. Interlock