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Home > Ideas & Tips > Generators - Why and Which One?

Generators - Why and Which One?

Lowe's Generators
choosing the right generator for your power needs

When selecting a generator, there are several important features to consider:

Wattage: The size of the generator you need depends on your power requirements. Generally, a higher-wattage generator lets you power more items at once.

Engine: All of our portable generators are gas-powered engines but inverter engines run quieter.

Run Time: Most people do not run their generator at full load all of the time so run time is often quoted at an average fraction of load - keep this in mind when determining your required run time.

Starting: Our generators are available with either pull cord start or electric start - some even have remote electric starters.

Mobility: Flat-free wheels, pneumatic wheels or simply a carry handle.

Outlets: the number of outlets available on the generator affects the number of items that you can power at the same time.

This handy calculator will help you determine your power requirements.

  1. 1 Select the items that you wish to power at the same time.
  2. 2 Note the total running watts of the items you want to power.
  3. 3 Note the total starting watts - this is the total starting watts of your selected list plus the highest starting watts of an individual item in your selected list.

Based on your selections your generator needs to supply:

Total Running Watts:

Total Starting Watts:

Enter Additional Requirements

If the running watts are not on a tool or appliance that you want included: You can estimate using the following equation: WATTS = VOLTS x AMPS.

Only motor-driven items will require additional starting watts. The additional starting watts can be estimated at 1-2x the running/rated watts.

Item Running (Rated) Watts Additional Starting Watts
Add New Item

These generators will meet or exceed your needs:

Frequently Asked Questions

How many watts does it take to power basic items in an average size house?

In a typical home, essential items will average 5000 - 7000 watts of power to run.

What is the difference between running watts and starting watts?

Running, or rated watts, are the continuous watts needed to keep items running. Starting watts are extra watts needed for two to three seconds to start motor-driven products like a refrigerator or circular saw, this is the maximum wattage the item will draw.

Why is only one additional starting watt item used to calculate your total starting watt requirement?

Unlike running watts, starting watts are only needed during the first few seconds of operation. In most cases, only one item will start or cycle at the same time, therefore this is the most accurate estimate.

What if I can't determine the running or the starting watt requirement for a tool or appliance?

If the running watts are not on the tool or appliance, you can estimate using the following equation: WATTS = VOLTS x AMPS.

What if I want backup power available at any time?

Consider a standby generator from Generac - a standby generator is permanently installed outside of your home to provide 24/7 backup power. It runs on your home's natural gas service - propane models are also available. Visit your Lowe's store for product and installation details.

automatic standy generators Learn More
why own a generator

Why own a generator

Power outages are more than just inconveniences for homeowners and businesses. We rely on electricity for refrigeration, heating and cooling, communications and much more. A generator can help to keep your equipment and devices running during an outage.

Power Outages

Power outages often last for hours, days or even weeks and can be difficult and costly if you are not prepared. Hurricanes, tornadoes and ice storms can cause disruption to our vulnerable power supply system, but, it's not just inclement weather that has the potential to turn the lights out on homes and businesses. Curious animals, automobile accidents, human error and utility failures can also trigger a blackout. Standby generators and portable generators are available to help make power outages more manageable.

Determining Your Generator Needs

The most important steps in finding the type of generator you need is to identify how you will use it most often. Consider these uses:

determining your generator needs for recreation


  • Camping
  • Boating
  • Tailgating
determining your generator needs for home


  • Power essential appliances, lights, etc.
  • Occasional protection like a sump pump
  • Power an entire home or most of a home
  • Short-term usage
  • Long-term usage where weather systems can bring damaging conditions again and again.
  • Use by elderly persons who may be less able to address a power situation
determining your generator needs for business


  • Power essential computers, networks, phones, etc
  • Power entire business
  • Provide temporary job-site electricity for tools and/or lights
  • Short-term occasional usage

In addition to these uses, consider any other power needs you might have.

Standby Generators

A permanently installed automatic standby generator provides 24 / 7 backup power protection and peace of mind for your family or business during a power outage. A standby generator runs on liquid propane or natural gas and, just like your central air conditioner, that works automatically when you need it and shuts off when you don't. There's no need to manually fuel or start a standby generator. It also eliminates the need for extension cords that portable generators require. Sizes are available to back up just essential circuits or provide complete coverage for large homes and businesses. Around the home, a standby generator can create enough power for nearly all of your needs — heating or cooling, lighting and cooking, all at the same time.

For more information on standby generators, see our Standby Generator Buying Guide.

Portable Generators

A portable generator is a great, mobile option for temporary power. It's essential to remember that portable generators are intended only as a backup solution to provide power for some basic household needs on an emergency basis, or to provide power for recreation, camping and power tools where electricity isn't available. Portable generators operate on gasoline or propane. They produce carbon monoxide gas and should never be run indoors, or near windows or doors.

See our Portable Generator Buying Guide for safety tips and more information.

Your store associate can help you determine the total wattage of power needed for your backup power needs.

standby generator buying guide

Standby Generator

Buying Guide

Power outages are difficult to deal with. Outages that last even a couple of hours are disruptive and those that stretch on for days or weeks can be uncomfortable and even costly. If you're looking for a long-term backup power solution that gives you dependable power whenever you need it, a standby generator is a good choice.

View Standby Generators (in-store only)

Standby Generator Basics

Standby generators are intended for permanent power protection — producing computer-friendly electricity of a higher quality than the power portable generators deliver. Standby generators operate automatically and run a weekly self-test to ensure proper response to an outage.

Standby generators are designed to run for extended periods using the permanent natural gas or liquid propane fuel supply that many homes or businesses already have. In the event of a power outage, a permanently installed standby generator returns your home or business to power within seconds, 24/7, even when you're away.

There are no extension cords to run or gasoline to refuel — a fully automatic standby generator senses an outage and begins producing power immediately. When power returns, it shuts itself off automatically and returns to standby mode. Because the generator is hard-wired into the electrical system of your home or business, appliances like furnaces, well pumps and lights will operate in addition to plug-in items.

Always follow the generator manufacturer's operating, maintenance and safety instructions.

How a Standby Generator Works

An automatic standby generator works by monitoring utility voltage 24 / 7 and runs off of your home's existing liquid propane or natural gas supply. When your electricity is interrupted, the generator detects the problem and goes to work.

  1. The controller in the generator monitors incoming voltage through the automatic transfer switch (ATS). See below for more information on the ATS.
  2. When utility power is interrupted, the controller waits 10-20 seconds, then signals the generator to start. Within seconds, the ATS transfers to generator voltage.
  3. The ATS does this by safely closing the utility line and simultaneously opening the power line from the generator. This will stop any "back feed" of power to the utility lines of neighbouring houses.
  4. Within 15 seconds, the standby system begins supplying electricity to the circuits you have chosen to be powered by your generator. The controller continues to monitor the utility line in order to be ready to transfer back to utility power when it returns.
  5. When the controller senses that utility line voltage has returned at a steady rate, it automatically transfers the electrical load back and resumes monitoring for another outage. The generator will continue to run for another minute to allow the engine to cool down.

Standby Generator Transfer Switches

If you have chosen an automatic standby generator, you will also need a separate device called an Automatic Transfer Switch (ATS) to connect the generator to your existing electrical system. Most automatic standby generators are pre-packaged with a transfer switch.

Although the generator creates the power, the transfer switch is really the core of your generator system. It is an electrical panel that allows you to safely connect a generator to your home's electrical circuits and is permanently installed near your main circuit breaker panel. As described above, it constantly monitors incoming utility power and determines when a true power outage is occurring, switching from utility power to emergency generator power and back again when utility power returns. Options include transfer switches that provide power to only essential circuits or to every circuit for whole-house coverage. Some allow for prioritization of optional circuits or load shedding, such as heating and cooling.

generator standby transfer switches

Do not attempt to install a transfer switch yourself. Installation of transfer switches may require local permits - but it always requires a professional electrician. The model of transfer switch will depend mainly on the size of your generator.

Finding the Right Size Standby Generator

Often, generators are pre-packaged with a transfer switch containing a predetermined number of circuits based on the generator's kilowatt (kW) power rating. Each circuit is directly connected to a matched circuit on the home's main circuit breaker panel, providing electricity to that specific appliance or area of the home. For example, with an 8kW generator packed with a ten circuit transfer switch, you can connect (1) lights and TV in the family room, (2) microwave and lights in the kitchen, (3) refrigerator, (4) power to the bathroom, (5) computer and home office, (6) garage door opener, (7) air conditioner, and (8) furnace.

Here are some options to consider:

Essential Circuit Coverage: Many homeowners choose to cover only their essential circuits during an outage. Choose from options that create a simple, economical solution that keeps basics covered during an emergency.

Managed Whole-House Coverage: If it is unlikely you will turn on every appliance at the same time (most people don't), a smaller generator paired with a power management switch provides whole-house coverage by managing the power requirements of individual appliances.

Complete Whole-House Coverage: When the power goes out, everything comes on and stays on — no matter how many circuits need to be backed up. Choose a backup power solution capable of covering every circuit in any size home for complete whole-house protection.

The most accurate way to select the right option is to have a Lowe's Installation Specialist conduct a load measurement of the circuits and items you intend to back up with your standby generator. An amp meter measures the power required as each appliance starts up, when it requires the greatest amount of power. The result of this load measurement gives you the total power requirement for backup power.

Air-Cooled and Liquid-Cooled Generators

An air-cooled generator uses a fan to force air across the engine for cooling. For most typical homes, air-cooled models provide exceptional value to homeowners interested in backing up critical circuits. Depending on the model, 8, 10, 12, or 16 key circuits in your main distribution panel can be powered by the generator during a power outage. A 20kW air-cooled standby generator offers up to whole-house protection for many homes.

A liquid-cooled generator uses an enclosed radiator system for cooling, similar to that in an automobile. Larger kW generators require larger engines for higher power output. Generally these generators will be liquid-cooled.

Standby Generators Frequently Asked Questions

Why size a generator by circuits and not watts?

You can simplify the job of sizing a standby generator by matching the circuits between your home's main electrical panel and the generator system's load center. On the other hand, figuring out the specific wattage requirements of appliances and other items in your home can be difficult since they are plugged into outlets all over the house. By identifying the circuits to back up, you can easily decide how large a generator is needed and what model will best fit those needs. All the identified circuits will have backup power available. A licensed electrician should determine the electrical load and identify the circuits to back up.

What's the advantage of an aluminum or composite generator enclosure?

Aluminum and composite enclosures are naturally rust and corrosion resistant. For salt air or high humidity conditions, aluminum or composite is highly recommended to ensure decades of worry free service.

Can an automatic standby generator replace utility service?

No — the generator fuel costs would be much more expensive than buying power from the utility Company since their cost to produce electricity is divided among thousands of customers.

Can I install the generator myself?

As an option, manufacturers offer systems pre-packaged and pre-wired with comprehensive installation instructions. You could perform the simpler site preparation steps and have a professional make the electrical panel and fuel connections, or you could complete the entire installation yourself. However, for safety reasons and to ensure adherence to all local, state and national electrical codes, particularly for non-pre-wired or larger systems, manufacturers recommend you use an authorized dealer or licensed contractor.

Does the generator have to be maintained?

Yes, simple maintenance is required. All generators require periodic oil and filter changes to ensure maximum performance for years of reliable service. Preventative maintenance kits are available. Refer to the owner's manual for routine maintenance procedures and schedules.

Can I purchase a service/maintenance contract?

Yes, service / maintenance contracts may be offered by your local installer / dealer for a worry-free ownership experience. You can inquire with them to determine availability and cost, which will be based on the level of service you require. Cost will also vary based on hourly labor rates in your local area.

I don't have natural gas at my house. How long will a generator run on my propane tank?

Run time will vary with the size of the generator and the appliance load being placed on it. The chart below shows hours of operation for a typical example: a 16kW generator running at half load.

16kW generator at 1/2 load
LP tank size (gallons) 10
hours of generator operation 5

Lowe's Installs Standby Generators

Consider a standby generator from Generac - a standby generator is permanently installed outside of your home to provide 24/7 backup power. It runs on your home's natural gas service - propane models are also available. Visit your Lowe's store for product and installation details.

automatic standby generators
portable generator buying guide

Portable Generator

Buying Guide

Electrical power is a requirement around the home. If you want protection from power outages but don't want to invest in a permanent backup generator, or if you need power for activities outside the home, a portable generator might be the solution. Portable generators can keep vital appliances running during an outage and offer mobile power for the camp site or job site.

Portable Generator Basics

Portable generators provide power for everything from home use to camping, construction and outdoor events. They can be used to supply electrical power to areas where there is no accessibility or during blackouts and power outages when no electrical power is available.

Outside the home, a small portable generator can provide power for TVs, small appliances, power tools and lights while camping. Medium to larger portable generators can be put to work at construction sites that are in need of electrical power to operate power tools such as drills, saws, paint sprayers and air compressors.

Always follow the generator manufacturer's operating, maintenance and safety instructions.

Backup Power with Portable Generators

Fuelled by gasoline or liquid propane liquid propane fuel, portable generators can back up your most important appliances during an outage, such as lights, your refrigerator, and your sump pump. Add a manual transfer switch and you can deliver the full output of your portable generator to your home's electrical system, letting you backup hardwired appliances.

Portable generators intended for backup use should be regularly maintained and tested for readiness. Make sure that you have a safe outdoor location to operate the generator, and that you are familiar with the manufacturer's operation recommendations.

Portable Generator Features

Portable generators are available in a wide range of sizes and with
a number of different features.

Features to consider include:

  • Circuit-breaker protected outlets to guard against generator overload
  • Larger fuel tanks for extra run time
  • Integrated fuel gauges to help prevent power interruptions
  • Power cleanliness for compatibility with sensitive electronic devices
  • Low-tone muffles for quiet operation
  • Fold-down handles and wheel kits for easy portability

Portable Generator Safety Tips

Before reading these tips, always read the Owner's Manual and instructions for your portable generator, which also reference portable generator safety tips. Carefully follow all instructions and warnings in order to safely start and operate the generator. Do NOT cut corners when it comes to safety.

These tips are merely supplemental and are not intended to substitute reading the Owner's Manual.

Carbon Monoxide and Ventilation

  • Portable Generator exhaust contains carbon monoxide, a deadly poison gas you cannot see or smell.
  • NEVER run a generator indoors or in partly enclosed areas such as garages.
  • ONLY use outdoors and far from windows, doors, vents, crawl spaces and in an area where adequate ventilation is available and that will not accumulate deadly exhaust gas.
  • Using a fan or opening doors and windows will not provide sufficient ventilation.
  • It is recommended that you install battery operated Carbon Monoxide alarms / detectors indoors according to manufacturer's instructions / recommendations.

Gasoline, Fuelling and Burn Safety

  • Gasoline is extremely flammable and explosive.
  • If tank is over-filled, fuel can overflow onto a hot engine and cause fire or explosion.
  • Do not overfill the fuel tank. Always allow room for fuel expansion.
  • Never add fuel while unit is running or hot. Allow generator and engine to cool entirely before adding fuel.
  • Never store a generator with fuel in the tank where gasoline vapours might reach an open flame, spark or pilot light.
  • Do not smoke near fuel or generator.
  • Many generator parts are hot enough to burn you during operation and while the generator is cooling after turning off. Avoid coming into contact with a hot generator.

Electrocution Hazard and Electrical Shock Hazards

  • Connecting a portable electric generator directly to your household wiring can be deadly to you and others. A generator that is directly connected to your home's wiring can 'back feed' onto the power lines connected to your home and injure neighbours or utility workers.
  • Do not connect your generator directly to your home's wiring or into a regular household outlet.
  • Always start or stop the generator only when no electrical loads are connected.
  • Overloading your generator can seriously damage your valuable appliances and electronics. Do not overload the generator. Do not operate more appliances and equipment than the output rating of the generator. Prioritize your needs. A portable electric generator should be used only when necessary, and only to power essential equipment.
  • Use the proper power cords. Plug individual appliances into the generator using heavy-duty, outdoor-rated cords with a wire gauge adequate for the appliance load. Overloaded cords can cause fires or equipment damage. Do not use extension cords with exposed wires or worn shielding.
  • Do not operate the generator in wet conditions such as rain or snow.
  • The generator must be properly grounded. If the generator is not grounded, you run the risk of electro caution. Check and adhere to all applicable federal, state and local regulations relating to grounding.

Generator Placement and Operation

  • Keep children away from portable generators at all times.
  • Allow at least five feet of clearance on all sides of the generator when operating.
  • Generators can be used during a wide variety of weather temperatures, but should be protected from the elements when not in use to prevent shorting and rusting.
  • Operate the generator only on level surfaces and where it will not be exposed to excessive moisture, dirt, dust or corrosive vapours.
  • Inspect the generator regularly and contact the nearest authorized dealer for parts needing repair or replacement.
  • Always disconnect the spark plug wire and place the wire where it cannot contact the spark plug to prevent accidental starting when setting up, transporting, adjusting or making repairs to the generator.

Portable Generator Frequently Asked Questions

What is the difference between rated watts and maximum (surge) watts?

Rated watts describe the amount of power the portable generator can produce continuously. Maximum wattage is the power that the generator can produce for short periods of time. Motor starting is a good example of maximum wattage requirements.

Can I use a portable generator for backup during a power outage?

Yes. You can plug household appliances and devices into a portable generator, but not all simultaneously.

Never plug your generator into an outlet in your home or business. If you would like to connect a portable generator to your home's wiring system, have a certified electrician install an approved manual power transfer switch in compliance with electrical codes.

What is a transfer switch?

A transfer switch allows you to connect a portable generator to your home's electrical system, while safely disconnecting you from the utility grid. This will eliminate any chance of a dangerous back-feed.

What is a back-feed?

A back-feed occurs when a generator is plugged into an electrical outlet, feeding power back onto utility lines. This creates a life-threatening hazard for any utility employees working to restore power to these lines.

Does the portable generator need to be grounded?

Yes. For safety, the generator must be properly grounded. If the generator is not grounded, you run the risk of electrocution. Check and adhere to all applicable federal, state and local regulations relating to grounding.

Can I vent the exhaust out of an enclosed area?

No. Never run the generator in the home or an enclosed area. Portable generators are designed to run outside where there is plenty of ventilation. Generator exhaust, like that of all gasoline engines, contains poisonous carbon monoxide. For more information, refer to Portable Generator Safety Tips above.

Can I use the generator during inclement weather?

Generators can be used during a wide variety of weather temperatures, but should be protected from the elements when not in use to prevent shorting and rusting. NEVER run a generator indoors.

How often should I perform routine maintenance?

Check your owner's manual for the recommended maintenance schedule.

Where can I purchase parts?

You can purchase parts through any authorized dealer. Refer to the dealer locator section on the manufacturer's web site to find a dealer near you.

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