How to Choose a Home Standby Generator | IB Lighting
How to Choose a Home Standby Generator | IB Lighting
Knowing how to choose a home standby generator correctly before you spend thousands of dollars is the difference between a system that performs exactly as expected during a...
Knowing how to choose a home standby generator correctly before you spend thousands of dollars is the difference between a system that performs exactly as expected during a real outage and one that fails the household at the moment it matters most. Most buyers approach this decision with a rough sense of the brands available and a price range in mind. Very few start from the technical variables that actually determine whether a specific generator covers their home adequately, installs correctly to code, and performs reliably under sustained load during the multi-day outages that make a standby generator necessary in the first place. This guide walks through every decision point in the correct sequence, from load calculation through fuel selection, brand evaluation, transfer switch sizing, and installation requirements, so you arrive at a purchasing decision grounded in your home’s actual needs rather than in a sales pitch.
⚡ IB Lighting’s Master Electrician-Founded Team Guides Every Generator Buyer Through This Process at No Charge
How to Choose a Home Standby Generator: Start with Load Calculation, Not Brand Selection
The most common and most expensive mistake in the home standby generator buying process is starting with brand research rather than load calculation. Brand matters, and we address it thoroughly later in this guide. But brand selection before load calculation is like choosing a truck before deciding what you need to haul. The right generator for your home is the one that covers your home’s actual electrical load under real outage conditions. That number must come first.
A load calculation identifies the peak simultaneous electrical demand your home will place on the generator during an outage, accounting for which appliances you want operational and what their combined draw looks like when they are all running at the same time. The generator you purchase must be capable of supplying that peak demand with enough margin above it to handle motor starting inrush currents from your HVAC compressor without stalling.
IB Lighting’s Master Electrician-founded team performs a load-based sizing conversation with every generator buyer before recommending a specific output level. That conversation takes less than fifteen minutes and prevents the single most common problem in the home standby generator category: a generator that is installed and discovered to be undersized only during the first real outage. Browse the full home standby generator collection at IB Lighting here after you work through the steps below.
Step One: Determine Your Home’s Peak Electrical Load
Your home’s peak simultaneous electrical load during an outage is the sum of the wattage drawn by every appliance and circuit you want running at the same time. Here is how to calculate that number before selecting a generator output level.
Identify Your High-Draw Appliances and Their Wattage
Start by listing the major electrical loads in your home and their approximate wattage requirements. The loads that dominate the calculation are typically:
| Appliance or Load | Typical Running Watts | Startup Surge Watts |
|---|---|---|
| Central AC (3-ton) | 3,500 to 4,500W | 12,000 to 16,000W |
| Gas Furnace Blower | 500 to 800W | 1,000 to 1,600W |
| Electric Water Heater | 4,000 to 5,500W | 4,000 to 5,500W |
| Well Pump (1HP) | 750 to 1,500W | 2,000 to 3,500W |
| Refrigerator and Freezer | 300 to 800W | 1,000 to 2,000W |
| Electric Range (all burners) | 8,000 to 12,000W | 8,000 to 12,000W |
| Sump Pump | 800 to 1,500W | 1,500 to 3,000W |
| Lighting and Outlets (whole home) | 2,000 to 4,000W | 2,000 to 4,000W |
| Level 2 EV Charger | 7,200W | 7,200W |
Apply the Load Calculation to a Generator Output Level
Add the running wattage of all loads you want operational simultaneously during an outage. Add the highest single startup surge from the list to account for motor starting. The resulting total is your minimum generator output requirement. Add 20 percent margin above that total to arrive at a comfortable operating output level that does not run the generator at or near its rated ceiling under real-world peak conditions.
A gas-appliance home with a 3-ton AC, gas furnace blower, refrigerator, well pump, and whole-home lighting and outlet load typically lands between 10,000 and 15,000 watts of combined running load. A 14kW to 18kW generator covers that load with comfortable margin. An all-electric home adding an electric water heater and electric range to the same base load can push the combined total above 20,000 watts, placing it in Generac 22kW to 24kW territory for whole-home coverage.
The Generac sizing resource at generac.com provides additional guidance on load calculation methodology for their specific generator lineup, which IB Lighting’s team uses alongside your specific appliance list before recommending an output level.
Step Two: Choose Your Fuel Type — Natural Gas vs Liquid Propane
Home standby generators run on one of two fuel types: natural gas or liquid propane. Some models, including several in Generac’s lineup, are dual-fuel capable and can operate on either. Choosing the right fuel type is a decision driven by your property’s fuel availability, not by generator preference.
Natural Gas: The Preferred Fuel Where Available
Natural gas is the preferred standby generator fuel for homes on utility gas service. A generator connected to the natural gas utility line draws from a continuous supply that does not require storage management, refilling, or the fuel availability anxiety that accompanies gasoline-fueled portable generators during regional weather emergencies. Natural gas infrastructure is physically separate from electrical distribution infrastructure, which means it typically remains operational during the grid outages caused by storms, equipment failures, and other events that trigger the generator’s need to operate.
The practical limitation of natural gas is geographic. Homes in rural areas, homes on well water without municipal services, and homes in regions where natural gas utility service is not available must use liquid propane as their standby fuel source.
Liquid Propane: The Solution for Homes Without Natural Gas Service
Liquid propane is a viable and widely used standby generator fuel that delivers equivalent performance to natural gas in most generator applications. LP generators store fuel in a propane tank on the property, which must be sized for the generator’s BTU consumption rate and the expected duration of outages in your area. A rule of thumb for LP tank sizing is to ensure at least 72 hours of full-load generator operation without refilling, which provides three days of continuous backup power through most residential weather-related outages without requiring fuel delivery during the storm event itself.
LP propane standby generators often produce slightly higher output on propane than on natural gas due to propane’s higher energy density per cubic foot, which is worth noting when comparing dual-fuel model specifications at different fuel types. IB Lighting’s team advises on LP tank sizing alongside every propane-fueled generator order.
Step Three: Select the Right Brand — Generac vs Kohler for Residential Standby Power
The residential home standby generator market is effectively a two-brand category at the quality level that IB Lighting carries: Generac and Kohler. Both are excellent. Both carry 5-year manufacturer warranties. Both produce generators that will serve a well-maintained residential installation for 15 to 20 years. The differences between them are real but are more nuanced than brand loyalty discussions typically acknowledge.
Generac: Market Leadership, Output Range, and Broadest US Service Network
Generac is the most widely installed home standby generator brand in the United States by a significant margin, with an estimated 70 percent residential market share at their peak installation rate. That market leadership has a practical consequence that matters for long-term ownership: Generac’s service technician network is the deepest in the country, meaning that finding a qualified Generac service technician in virtually any US market is straightforward in a way that is not always true for every competing brand.
Generac’s residential air-cooled lineup spans 7kW to 24kW, covering the full range from essential circuit partial-home configurations through whole-home coverage for large all-electric homes. Their G-Force engine, True Power Technology for clean harmonic distortion output, Mobile Link cellular monitoring, and Quiet-Test weekly exercise mode are standard features across their residential lineup. Browse IB Lighting’s full Generac home standby generator lineup here.
Kohler: Engineering Precision and PowerBoost Motor Starting Technology
Kohler brings over a century of power generation engineering to the residential standby market. Their residential air-cooled lineup spans 8.5kW to 20kW and includes PowerBoost technology, which provides above-rated output momentarily to handle large motor starting loads such as central AC compressor startup inrush without the generator stalling or limiting. This means a Kohler 14kW or 20kW unit may handle startup surge scenarios that push a comparably rated Generac unit closer to its ceiling, making Kohler a particularly strong choice for homes with large single-stage HVAC systems where startup inrush is a meaningful sizing variable.
Kohler’s aluminum enclosure construction is a standard feature across their residential lineup, and their RXT series automatic transfer switch is widely regarded by electricians as one of the most reliable ATS configurations in the residential generator category. Browse IB Lighting’s Kohler standby generator range here.
Not Sure Which Brand or Output Level Is Right for Your Home?
IB Lighting’s Master Electrician-founded team walks through your home’s load profile, fuel source, and installation requirements before recommending a specific generator and transfer switch configuration. Free guidance, no obligation.
Step Four: Select the Correct Automatic Transfer Switch
Understanding how to choose a home standby generator requires understanding that the generator unit itself is only part of the system. The automatic transfer switch (ATS) is the component that makes the standby generator genuinely automatic. It monitors utility power around the clock, detects outages, signals the generator to start, transfers your home’s electrical load to the generator in seconds, and reverses the sequence when utility power is restored. Without a correctly sized and matched ATS, a standby generator is not a standby generator. It is an engine sitting outside your house doing nothing when the power goes out.
Transfer Switch Sizing Must Match Your Main Panel Amperage
The transfer switch amperage rating must match your home’s main electrical panel amperage. A 200-amp main panel requires a 200-amp ATS. A 100-amp panel requires a 100-amp ATS. Installing a transfer switch rated below your panel’s main breaker amperage is a code violation under NEC Article 702 that will fail electrical inspection. IB Lighting confirms the correct ATS amperage for every generator order before it ships. Browse the full range of Generac and Kohler transfer switch kits here.
Transfer Switch Must Be Matched to Your Specific Generator Model
Generac and Kohler both produce ATS units engineered to integrate specifically with their generator control systems. The communication between the ATS and the generator’s control board enables the automatic exercise cycle, fault monitoring, and remote status reporting that modern standby systems provide. Using a mismatched or incompatible ATS with a Generac or Kohler generator is not just a performance compromise. It is a warranty condition violation that voids the manufacturer warranty on the generator and the ATS simultaneously. IB Lighting confirms generator-to-ATS compatibility for every order before it ships.
Step Five: Understand Installation Requirements Before You Order
Knowing how to choose a home standby generator requires knowing what the installation process involves before the generator arrives, because installation variables can affect the total project cost and timeline in ways that surprise buyers who did not account for them in advance.
Licensed Electrician for Electrical Work — No Exceptions
Every home standby generator installation requires a licensed electrician for the electrical panel connection, transfer switch installation, and any new circuit work associated with the system. This is both a legal requirement in virtually every US jurisdiction and a warranty condition for both Generac and Kohler. Self-installation of the electrical components voids the manufacturer warranty on all system components and creates a code violation that will fail inspection.
The permit process involves obtaining an electrical permit from your local authority having jurisdiction before installation begins, followed by an electrical inspection after the work is complete. The inspector verifies that the transfer switch is correctly sized for the service, the generator is properly bonded and grounded, and all wiring meets the applicable NEC requirements. A properly permitted and inspected installation is a code-compliant, insurable, warranty-valid system. An unpermitted installation is none of those things.
Licensed Gas Contractor for Fuel Line Connection
The connection of the generator to the natural gas utility line or liquid propane system must be made by a licensed gas contractor or plumber with the appropriate gas piping credentials for your state. The gas line must be sized to deliver the generator’s full BTU demand at the operating pressure the unit requires, in addition to continuing to supply all other gas appliances in the home that may be operating simultaneously. A gas line that is undersized for the combined demand will cause the generator to run lean, reducing output and potentially triggering a low-pressure shutdown during an outage. Your gas contractor can perform the gas line sizing calculation before installation begins. The governing fuel gas code is the NFPA 54 National Fuel Gas Code.
Concrete Pad and Clearance Requirements
The generator must be mounted on a concrete pad or approved composite pad at the manufacturer-specified dimensions. Both Generac and Kohler publish minimum pad dimensions for their residential units in their installation manuals. The generator must also be positioned at the manufacturer-specified clearances from windows, doors, gas meters, electrical service entrance equipment, and property lines. These clearances are code requirements enforced during the installation inspection and cannot be waived for site convenience. IB Lighting’s team advises on clearance requirements for specific models before your order ships so you can prepare the installation location correctly before the unit arrives.
Step Six: Plan for Maintenance from Day One
A standby generator requires periodic maintenance to remain in a reliable, warranty-valid operational condition throughout its service life. The maintenance schedule Generac and Kohler publish includes oil and filter changes at specified intervals, spark plug inspection and replacement, air filter service, battery condition checks, and cooling system inspection where applicable. Neglecting the maintenance schedule creates grounds for warranty claim denial on failures that are plausibly related to the neglected service.
The most practical approach to maintenance planning is to purchase the first maintenance kit at the same time as the generator so it is on hand when the first service interval arrives. IB Lighting carries Generac maintenance kits and accessories. Browse the full Generac generator accessories range here to add the appropriate maintenance kit to your initial order.
Common Mistakes to Avoid When Choosing a Home Standby Generator
❌ Choosing Output Level Based on Square Footage Alone
Square footage is a rough proxy for generator sizing, not an accurate load calculation method. A 3,000 square foot home with all-gas appliances has a dramatically different peak electrical load than a 3,000 square foot all-electric home. Always calculate actual connected load rather than using square footage as the sizing input.
❌ Buying a Generator Without Confirming Transfer Switch Compatibility
Ordering a generator without simultaneously confirming the correct matched transfer switch creates the most common installation delay in the standby generator category. The ATS must be ordered alongside the generator, sized to the panel, and confirmed compatible with the specific generator model. IB Lighting resolves this for every buyer before the order ships.
❌ Ignoring Gas Line Sizing Until Installation Day
A gas line that cannot supply the generator’s full BTU demand at operating pressure is discovered during installation or during the first extended outage operation when the generator runs lean and shuts down. Gas line capacity must be confirmed before the generator arrives. This is your gas contractor’s job, and it should happen before the installation date is scheduled.
❌ Purchasing from a Source That Cannot Guarantee Warranty Validity
Grey market generators, open-box units, and units sold through unauthorized channels carry no valid US manufacturer warranty. The price savings on such units are consistently smaller than the financial exposure of a single major component failure during the warranty period. IB Lighting sources only from legitimate manufacturer-authorized channels.
❌ Skipping Warranty Registration After Installation
Both Generac and Kohler require product registration within a specified period after installation to activate the full extended warranty coverage. Missing the registration deadline results in reduced base warranty coverage. IB Lighting walks every customer through the registration process after delivery to prevent this avoidable coverage reduction.
❌ Underestimating Future Load Growth When Sizing
A generator sized for your current electrical load that becomes undersized when you add an EV charger, convert from gas to electric appliances, or add a home addition is a generator that must be replaced before the end of its service life. Account for planned load additions within the next five to ten years when selecting an output level. Sizing up by one tier at purchase is almost always more cost-efficient than replacing the system later.
Want IB Lighting’s Team to Walk Through This Process with You?
IB Lighting’s Master Electrician-founded team works through every step of the generator selection process with buyers before any order is placed. Load calculation, fuel selection, brand and model recommendation, transfer switch sizing, and installation requirement briefing. Free, no obligation, no upselling.
Frequently Asked Questions: How to Choose a Home Standby Generator
What is the first step in choosing a home standby generator?
The first step in how to choose a home standby generator is calculating your home’s peak simultaneous electrical load. This means identifying every appliance and circuit you want operational during an outage and adding their running wattage together, plus accounting for the highest motor starting inrush current from your HVAC system. That total, plus a 20 percent margin, determines the minimum generator output level you need. Starting with brand research before this calculation is the most common and most expensive mistake in the generator buying process.
What size home standby generator do I need?
The right generator size depends on your home’s actual connected electrical load, not on square footage alone. A gas-appliance home with standard residential loads typically needs 14kW to 18kW for whole-home or near-whole-home coverage. An all-electric home with electric water heater, electric range, and central HVAC typically needs 20kW to 24kW. Homes with high-draw specialty loads such as EV chargers, workshops, or dual HVAC zones lean toward the upper end of those ranges. IB Lighting’s Master Electrician-founded team performs load-based sizing guidance before recommending a specific output level for your home.
Should I choose Generac or Kohler for a home standby generator?
Both Generac and Kohler are excellent choices for residential standby power. Generac has the broadest residential output range from 7kW to 24kW, the deepest US service technician network, and the highest residential market share. Kohler’s PowerBoost technology handles large motor starting loads particularly well, making their 14kW and 20kW units strong choices for homes with large central HVAC systems where startup surge is a sizing variable. IB Lighting carries both brands and provides honest guidance on which fits your specific home and installation before you commit to either.
Do I need a transfer switch with a home standby generator?
Yes. A home standby generator requires an automatic transfer switch (ATS) to function as an automatic backup power system. The ATS monitors utility power, detects outages, starts the generator, and transfers your home’s electrical load to generator power automatically without any human action. Without an ATS, the generator cannot detect outages or transfer power to your home. Both Generac and Kohler require a matched ATS as a condition of their manufacturer warranty. IB Lighting confirms the correct ATS for every generator order before it ships. Browse transfer switch kits here.
Is natural gas or propane better for a home standby generator?
Natural gas is the preferred fuel for homes with utility gas service because it provides a continuous, unlimited fuel supply from the utility line without storage management or refilling requirements. Propane is the appropriate choice for homes without natural gas service, providing equivalent performance with a properly sized LP tank on the property. The fuel decision is driven by availability at your specific property, not by generator performance preference. Both fuels work well in residential standby applications when the fuel supply is correctly sized and installed by a licensed gas contractor.
How long does a home standby generator installation take?
A standard residential home standby generator installation typically takes one to two days for the combined electrical and gas work, not counting the concrete pad preparation which may require a separate curing period before the generator can be mounted. The timeline also includes the permit application and inspection scheduling process, which varies by jurisdiction from a few days to a few weeks. Preparing the installation site, including the concrete pad and any gas line upgrade work, before the generator arrives minimizes the total project timeline. IB Lighting advises on all pre-installation requirements before your unit ships.
How much does a home standby generator cost installed?
Total installed cost for a residential home standby generator varies significantly based on the generator’s output level, the transfer switch configuration, the complexity of the electrical and gas work at your specific property, permit fees, and any infrastructure upgrades required such as gas line enlargement or electrical panel upgrade. As a general range, a complete residential standby generator installation including generator, ATS, concrete pad, electrical labor, gas contractor labor, and permit fees typically falls between $5,000 and $15,000 or more depending on those variables. IB Lighting’s generator pricing is displayed accurately in your cart per manufacturer MAP policy. Contact our team for a complete picture of what to budget for your specific installation scenario.
Does IB Lighting help with generator selection before purchase?
Yes. IB Lighting’s Master Electrician-founded team provides free pre-sale generator selection guidance covering load calculation, fuel type, brand and model selection, transfer switch sizing, and installation requirement briefing before any purchase is made. This guidance is free, carries no purchase obligation, and is based on your specific home’s characteristics rather than on any preference for a particular product. Call (800) 674-9019 or visit the Expert Advice hub to start the conversation before you buy anything.
How to Choose a Home Standby Generator: The Decision in the Right Order
The correct sequence for how to choose a home standby generator is: load calculation first, fuel type second, brand and output level third, transfer switch fourth, installation planning fifth, and maintenance planning sixth. Every buyer who follows that sequence arrives at a purchasing decision that matches their home’s actual requirements. Every buyer who skips steps or reorders them risks discovering the consequences during the first real outage, which is exactly the wrong moment for discovery.
IB Lighting walks through every step of that sequence with buyers at no charge and with no pressure to purchase any specific product. The team carries Generac and Kohler across the full residential output range, ships every generator with free nationwide freight delivery and free freight insurance, confirms transfer switch compatibility before every order ships, and provides post-delivery warranty registration support to ensure coverage activates correctly.
Browse the full home standby generator collection here, explore Generac here and Kohler here, or call our team at (800) 674-9019 to start the selection process before you commit to any purchase. The Expert Advice hub has additional resources covering every topic in this guide in greater technical depth.
Shop Home Standby Generators at IB Lighting
Free nationwide freight delivery. Free freight insurance. Transfer switch compatibility confirmed before every order ships. Master Electrician-founded team. Full manufacturer warranty on every unit. No sales tax in select states.
📞 (800) 674-9019 | ✉ support@iblighting.com | 22325 W Warren Ave, Dearborn Heights, MI 48127