What You Need to Know Before Installation Begins
A backup generator sits outside your home and connects to your electrical panel, automatically powering essential circuits when the grid goes down. Installation is not a DIY project for most homeowners — it requires permits, inspections, and work inside your electrical panel that must be done by a licensed electrician. The process typically takes one to three days once the generator arrives, though permitting can add weeks to the overall timeline.
You will need to decide between a portable generator (which you manually connect with a cord) and a standby generator (which is permanently installed and switches on automatically). Standby generators cost significantly more upfront but require no action during an outage. Portable generators are cheaper but demand that you be home, awake, and able to run extension cords safely during an emergency.
Before you contact an installer, know your home's electrical panel location, the size of your service (usually 100, 150, or 200 amps), and which circuits you want backed up. This information helps the installer give you an accurate quote and timeline.
Key Takeaways
- Standby generators require a licensed electrician, a building permit, and an inspection — portable generators do not, but they must be manually connected and operated.
- Your generator size depends on which circuits you want to power; a whole-house system costs more than one that backs up only essential loads like heating and refrigeration.
- Installation involves running a gas line (for natural gas models) or propane line, running electrical conduit from the generator to your panel, and installing a transfer switch inside the panel.
- Permitting timelines vary by municipality; contact your local building department before hiring an installer to learn the current wait time and required documents.
- A licensed electrician must do all work inside your electrical panel; attempting this yourself creates a serious shock and fire hazard.
Choosing Between Standby and Portable Generators
A standby generator is bolted to a concrete pad outside your home, connected to your gas or propane line, and wired into your electrical panel through a transfer switch. When power fails, it detects the outage and starts automatically within seconds. You do nothing. These units run on natural gas (if your home has gas service) or propane (which you store in a tank). They cost between $3,000 and $15,000 installed, depending on size and fuel type, and they require a permit and inspection.
A portable generator is a self-contained unit you store in a garage or shed. During an outage, you wheel it outside, fill it with gasoline or propane, plug in extension cords to power specific devices, and start it manually. Portable units cost $500 to $3,000, need no permit, and take minutes to set up — but they are loud, produce carbon monoxide (so they must run outside), and cannot power your whole home at once. They are best for backing up a few circuits or as a temporary solution while you plan a standby system.
If you want automatic backup and can afford the upfront cost, a standby generator is the practical choice. If you want to test backup power first, or if your budget is tight, start with a portable unit and upgrade later.
Sizing Your Generator and Choosing Which Circuits to Back Up
Generator size is measured in kilowatts (kW). A small standby unit might be 7 kW; a large whole-house system might be 20 kW or more. The size you need depends on which circuits you want to power during an outage. You do not have to back up everything — most homes back up essential loads only, which keeps costs down and makes the generator smaller and cheaper to run.
Essential circuits typically include your furnace or heat pump, refrigerator, well pump (if you have one), sump pump, water heater, and a few outlets for lights and charging devices. Air conditioning, electric dryers, and electric ranges are power-hungry and usually left off the backup list. An electrician can calculate your load by reviewing your panel and your utility bills, then recommend a generator size that covers your chosen circuits.
If you want to power your whole house, you need a larger generator — usually 15 to 20 kW for a typical home. This costs more to buy and install, and it uses more fuel. Many homeowners find that backing up 50 to 70 percent of their home's circuits is a good balance between cost and peace of mind.
The Permitting and Inspection Process
Before any work begins, your installer must obtain a building permit from your local code enforcement office or building department. This permit ensures the installation meets electrical and safety codes. The permit process usually requires the generator's model number, the fuel type, the proposed location, and the installer's license number. Processing times vary — some municipalities issue permits in a few days, others take several weeks.
Once the permit is issued, the installer can begin work. After installation is complete, a municipal inspector visits your home to verify that the generator, transfer switch, gas line, and electrical connections meet code. The inspector checks that the generator is properly grounded, that the transfer switch is correctly wired, that gas lines are pressure-tested, and that all connections are find. If the inspection passes, you receive a certificate of compliance, and the system is legally operational.
If the inspection fails, the installer must correct the issue and request a re-inspection. This can add days or weeks to your timeline. Contact your building department before hiring an installer to learn the current permit wait time and whether your municipality has any specific requirements for generator installations.
What Happens During Installation Day
Installation typically unfolds in this order: the concrete pad is poured (if not already in place), the generator is positioned and bolted down, the fuel line is run from the generator to your gas meter or propane tank, the electrical conduit is run from the generator to your home's electrical panel, the transfer switch is installed inside the panel, and the generator is wired to the transfer switch. The electrician then tests the system, confirms that the generator starts automatically when power is cut, and verifies that all circuits switch over correctly.
The work inside your electrical panel is the most time-consuming and the most critical. The electrician must shut off the main breaker, install the transfer switch in the available space, connect the generator leads to the switch, and reconnect the circuits you want backed up. This work is dangerous — your panel contains live electricity even when the main breaker is off — which is why it must be done by a licensed electrician.
On the day of installation, clear the area around where the generator will sit, may support the electrician has access to your electrical panel, and plan to be home so you can answer questions about which circuits matter most to you. The installer will show you how to operate the system, how to refuel (if applicable), and what maintenance is needed.
Fuel Options: Natural Gas, Propane, or Diesel
Most residential standby generators run on natural gas or propane. Natural gas is convenient if your home already has gas service — the generator connects to your existing gas line, and you never have to refuel. The downside is that natural gas is supplied by your utility, and during a widespread outage, the gas system may also fail or be shut down for safety. Propane is stored in a tank on your property, so it is available even if the utility system is down. The downside is that you must monitor the tank level and arrange refills.
Some standby generators can run on either fuel (called dual-fuel models), giving you flexibility. Portable generators typically run on gasoline, which is widely available but must be stored safely and can degrade over time if not used regularly. Diesel generators are less common in residential settings but are extremely durable and fuel-efficient.
For most homeowners, natural gas is the simplest choice if available. If you want maximum independence from utility systems, propane is the better option — just plan for regular tank maintenance and refills.
Maintenance and Long-Term Care
A standby generator requires regular maintenance to stay ready for an outage. Most manufacturers recommend running the generator under load for 20 to 30 minutes once a month to keep the engine in good condition and prevent fuel from gumming up the carburetor. Some generators have automatic self-test features that do this on a schedule you set. Your installer will explain the maintenance routine for your specific model.
You should also have the generator serviced annually by a may have access to technician, who will check the oil, air filter, spark plugs, and fuel system. If your generator runs on propane, the tank should be inspected annually for leaks and corrosion. Keep the area around the generator clear of debris, snow, and vegetation so air can flow freely for cooling.
If your generator sits unused for months, the fuel can separate or degrade. Some owners add fuel stabilizer to the tank or run the generator periodically to keep the fuel fresh. Your installer or the generator's manual will specify what is needed for your model.
Frequently Asked Questions
Do I need a permit to install a portable generator?
No. Portable generators do not require a permit or inspection because they are not permanently wired to your home's electrical system. However, you must follow safety rules: run the generator outside at least 20 feet from windows and doors to prevent carbon monoxide from entering your home, use heavy-duty extension cords rated for outdoor use, and never refuel while the engine is running or hot.
Can I install a standby generator myself?
You can pour the concrete pad and prepare the site, but the electrical work must be done by a licensed electrician. Work inside your electrical panel carries a serious risk of electrocution and fire. The permit and inspection also require that a licensed professional do the installation, so attempting it yourself will not pass code.
How long does a standby generator last?
A well-maintained standby generator typically lasts 20 to 30 years. The engine itself may last longer, but other components like the transfer switch or fuel system may need replacement sooner. Regular maintenance and annual service extend the life of the unit significantly.
What if my home does not have natural gas service?
You can install a propane-powered standby generator instead. A propane tank is buried or placed above ground near your home, and the generator connects to it via a buried or above-ground line. Propane is reliable and widely available, though you must monitor tank levels and arrange refills. Some installers also offer diesel generators as an alternative.
Will my generator run during a natural gas outage?
Only if it runs on propane or another fuel stored on your property. A natural gas generator depends on the utility's gas supply, which may be shut down or unavailable during a widespread outage. If you want backup power that works regardless of utility status, choose a propane or diesel model.