Portable Generator FAQs

If you’re still deciding between portable and standby, the Home Generator Sizing Guide and General Generator FAQs are good places to start.

What size portable generator do I need for my house?

It depends on whether you want to run only essentials or try to power a larger portion of the home. For typical U.S. homes:

• Basic essentials only (fridge/freezer, a few lights, phone/Internet, small window AC or space heater): often 3,000–5,000 W is enough with careful load management.
• Essentials + some comfort (fridge, lights, well or sump pump, a small central AC or multiple window units): many households land in the 7,500–12,000 W portable range.
• Whole-house coverage from a portable is uncommon and usually impractical. If you truly want “almost everything” powered, that’s typically a job for a right-sized standby generator instead.

The key question is not “Can this generator power my entire panel?” but rather “Which specific circuits do I want to back up, and what is their combined running and starting load?”

Can a 7,500 watt portable generator run a house?

A 7,500 W (7.5 kW) portable generator can run a surprising amount of a typical home’s essential loads when it’s connected through a proper transfer switch and used thoughtfully. For many gas-heated homes, 7,500 W is enough to cover:

• Refrigerator and freezer
• Well or sump pump (often not at the same instant as other big loads)
• Lighting in key rooms
• Home office/electronics
• Possibly a small central AC or a couple of window units, if sized carefully

A 7,500 W unit is typically rated around 30–31 continuous amps at 240 V, which is enough for many “essentials-plus” setups as long as:

• You avoid running electric ranges, large electric dryers, and big shop tools.
• You pay attention to what’s running at the same time (for example, don’t start the well pump and AC at the exact same moment).
• Your central AC system, if used, is on the smaller side or has a soft-start kit.

A 7,500 W portable will not substitute for a properly sized whole-house standby in a large, all-electric home. But for many gas-heated homes, it’s a solid “sweet spot” for outage comfort.

Is a 10,000–12,000 watt portable generator enough for most homes?

For many homes with gas heat and gas water heat, a 10,000–12,000 W portable can comfortably cover:

• Refrigerator and freezer
• Well or sump pump
• Lighting and outlets in several rooms
• Home office equipment
• One reasonably sized central AC or several window units (if loads are managed)

Generators in this size range usually provide around 40–50 amps at 240 V. That’s enough capacity for many homes’ essentials and some comfort loads, but you still need to:

• Choose which circuits are backed up via your transfer switch.
• Be aware of large motor starting surges (AC, pumps, compressors).
• Avoid running high-demand electric heat, ranges, and dryers simultaneously.

If you find yourself wanting to power everything without thinking about what’s on, a properly sized standby system is usually a better fit.

How do I connect a portable generator to my home safely?

The safest and code-compliant way is to use a transfer switch or interlock kit designed for generators. The exact equipment depends on your panel and local code, but the general options are:

• A pre-wired generator transfer panel that feeds a small subpanel of selected “generator circuits.”
• A mechanical interlock kit on your main panel that prevents the main breaker and generator breaker from being on at the same time.
• A manual or automatic transfer switch located near the main service equipment.

For more detail on your options, see Transfer Switch vs. Interlock.

What you should never do is “backfeed” the panel by using a homemade cord into a dryer or range receptacle. That’s dangerous for you, dangerous for line workers, and it violates electrical codes.

A licensed electrician can size the transfer equipment, ensure the neutral and grounding are handled correctly, and make sure everything passes inspection.

Can I run my portable generator inside the garage?

No. Portable generators must be run outside.

Even with the garage door open, a portable generator in a garage or under an attached carport can allow carbon monoxide (CO) to seep into the home. CO is colorless and odorless and can accumulate to dangerous levels before anyone notices.

General safety guidance is to:

• Run portable generators outdoors, away from windows, doors, and vents.
• Follow the clearances and placement instructions in the owner’s manual.
• Use heavy-duty, outdoor-rated extension cords or a proper inlet and transfer switch.
• Make sure your home has working CO detectors.

For more safety details, see the U.S. Consumer Product Safety Commission’s portable generator safety guidance .

How long can I run a portable generator continuously?

Most air-cooled portable generators are designed for extended use at partial load, but not to run at full output 24/7 without rest or maintenance. What limits runtime is a mix of:

• Fuel capacity and how you’re refueling.
• Oil change intervals (many portables specify 50–100 hours between oil changes).
• Ambient temperature and ventilation around the unit.
• How close you are to the generator’s maximum rating.

In real outages, many homeowners run portables for several hours at a time, then shut them down periodically to cool, check oil, and refuel during safe daylight conditions. For longer events, standby units that tie into natural gas or larger propane tanks are usually more practical than trying to keep a portable running around the clock.

Are inverter generators better for home backup?

Inverter generators produce cleaner power with lower harmonic distortion and can automatically throttle their engine speed based on load. Compared with conventional open-frame portables:

• They’re typically quieter.
• They often have better fuel efficiency at light load.
• They are generally more electronics-friendly.

The trade-offs:

• Inverter units often cost more per watt of capacity.
• Many popular inverter models top out around 3,000–7,000 W.

For smaller essential loads, an inverter generator is an excellent choice. For larger whole-home loads, a conventional higher-wattage portable or a standby system is often more practical.

Can a portable generator run a central AC?

Sometimes—if the generator is large enough, the AC system is reasonably efficient, and starting surge is managed. In practice:

• Smaller 2–3 ton systems may be able to run on a 7,500–12,000 W portable, especially with a soft-start kit and careful load management.
• Larger 4–5 ton systems often push beyond what’s comfortable for typical portables and may require a standby generator instead.

Before counting on a portable to run central air, you should:

• Gather the AC nameplate data (amps, volts, LRA).
• Estimate running and starting kW for the system.
• Confirm with your electrician and HVAC contractor that your plan is realistic and safe.

Do I still need a transfer switch if I only plug loads in directly?

If you’re only plugging devices directly into the generator’s receptacles with extension cords, you are not backfeeding the house wiring, and a transfer switch is not strictly required for those cords.

However, this approach has limitations:

• It’s easy to overload a single receptacle or cord if you’re not careful.
• You can’t power hard-wired loads (like a furnace, well pump, or central AC) without a proper interconnection.
• Running multiple cords through doors and windows can be inconvenient and a tripping hazard.

As soon as you want to power household circuits—for example, a furnace circuit, a well pump circuit, or multiple rooms—a code-compliant transfer switch or interlock installed by an electrician is the right path.

To understand what your specific home can run on a portable, open the generator sizing calculator and choose an “essentials-only” scenario. Then have an electrician confirm the final setup and transfer equipment.

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