What Size Generator to Run Sump Pump For Power Outages?

Don’t take chances with your home’s sump pump system during power outages. This guide explains what size generator to run sump pump effectively, ensuring your home is protected from flooding.

If you live in an area that’s prone to flooding, you know how crucial it is to have a reliable sump pump to keep your basement or crawl space dry.

However, what happens when the power goes out? That’s where a generator comes in handy. But what size generator do you need to run your sump pump?

It’s an important question to consider, as a generator that’s too small won’t provide enough power to run your pump, while one that’s too big can be costly and inefficient.

In this article, we’ll explore the factors to consider when choosing the right size generator to run your sump pump, ensuring you’re prepared for any power outage.

What Size Generator to Run Sump Pump?

Recommended Generator Size for Sump Pump

Sump Pump Sizes  AmpsWattagesRecommended Generator Size
1 hp102,0004,000 – 5,000 watts
1/2 hp61,000 – 1,0503,000 – 3,500 watts
3/4 hp81,5003,000 – 3,500 watts
1/4 hp3.5 to 3.8550 – 600e2,000 – 2,500 watts
1/3 hp3.8 to 4800 – 9002,500 – 3,000 watts

What Size Generator to Run Sump Pump?

When it comes to selecting the right generator to run your sump pump, it’s important to consider both the power requirements of the pump and the capacity of the generator itself.

A 2000-watt generator can typically handle a sump pump with a horsepower of 1/2, 1/3, or 1/4, but it may struggle to maintain performance during extended power outages.

For optimal performance and reliability, we recommend investing in a generator with a capacity of 4000-5000 watts, which can provide enough power to run your sump pump, as well as other essential household appliances like refrigerators and microwaves, without overloading the system.

By selecting a generator with sufficient capacity, you can ensure that your sump pump will continue to operate smoothly and efficiently, even in the event of a prolonged power outage.

Let’s give you an example

Let’s say you have a 240-volt sump pump with a running amp of 8 and a starting amp of 12. To determine the wattage required to run your sump pump, you need to use the power formula:

Watts = Amps x Volts

So, for the running wattage, you have:

Watts = 8 x 240 = 1920 watts

And for the starting wattage, you have:

Watts = 12 x 240 = 2880 watts

Remember to add an additional 10-20% to the total wattage to account for power losses. In this case, we’ll add 20%, which brings the total wattage to 3456 watts.

Based on these calculations, you will need a generator with a minimum wattage rating of 3500 to ensure that your sump pump runs smoothly without overloading the generator.

Check out what can a 4000W Generator Run if you want to run multiple appliances.

What are Starting Watts and Running Watts?

Starting watts refers to the peak power output a generator can produce for a short period to start up electrical devices with high initial power demands.

Running watts refers to the continuous power output a generator can produce to keep these devices running over time.

Understanding the starting and running watt requirements of your electrical devices is important when selecting a generator to ensure it can meet the power demands of your devices without overloading or damaging the generator.

Why Do I Need a Generator for My Sump Pump?

A generator can be a crucial backup power source for your sump pump during power outages or emergencies. Without power, your sump pump won’t function, leaving your basement vulnerable to flooding and water damage.

A generator can provide temporary power to your sump pump, allowing it to continue operating and protecting your home from water damage.

Additionally, a generator can power other essential appliances, such as refrigerators, lights, and communication devices, during an extended power outage, helping to ensure your safety and comfort.

In short, having a generator for your sump pump can provide peace of mind and help protect your home and family from the damaging effects of water and power outages.

You can also run a sump pump using a solar system but I would recommend purchasing one regardless of the use. It might come in handy during long power outages.

Recommended Read: What Size Generator to Run a Well Pump?

Power Rating of Sump Pumps

Sump pumps, like other electronic appliances, have both starting and running wattages that are important to consider when selecting a generator to power them.

The wattage/power ratings can typically be found on the energy label of the sump pump, which is usually indicated in yellow color and provides information on the frequency, amps, voltage, and horsepower of the pump.

In addition to checking the energy label, it’s recommended to review the user manual or use a device like a multimeter to calculate the precise wattages and amps your sump pump is using.

This can help you determine the minimum generator size and power rating needed to safely and efficiently power your sump pump during power outages or emergencies.

It’s important to note that these calculations are just an estimation, and it’s always best to consult with a professional electrician or generator specialist to ensure that you select the right generator for your specific needs.

If you want to know why generators are important, read this research about power outages on CNN, or this power outage news on Washington Post.

Frequently Asked Questions (FAQs)

How Do I Know What Size Generator to Run My Sump Pump?

The size of the generator you need depends on the power requirements of your sump pump. Check the sump pump’s user manual or label to determine its wattage requirements. Then, select a generator with a rated wattage equal to or greater than the pump’s wattage requirement.

Can I Run Other Appliances on the Same Generator That Powers My Sump Pump?

Yes, but you must ensure that the generator has enough power to handle all connected appliances simultaneously. The generator’s rated wattage should be equal to or greater than the combined wattage requirements of all connected appliances.

Can I Use a Portable Generator to Power My Sump Pump?

Yes, portable generators are a popular option for powering sump pumps during power outages. Be sure to place the generator outside in a well-ventilated area and away from any open windows or doors to prevent carbon monoxide poisoning.

What Fuel Type Should I Choose for My Generator?

Generators can run on gasoline, diesel, propane, or natural gas. Choose a fuel type that is readily available in your area and that you feel comfortable handling and storing. Keep in mind that some fuel types may require more maintenance or have higher emissions than others.

Can I Run My Sump Pump Continuously on a Generator?

Yes, but it is not recommended. Running a sump pump continuously on a generator can put a strain on the generator’s engine and reduce its lifespan. It is better to only run the sump pump when necessary and conserve fuel for emergencies.



Fareed, the highly skilled electrical expert, boasts 5 years of extensive experience in proficiently maintaining, repairing, diagnosing, and installing a diverse range of electrical systems.

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