You can plug in a portable generator two ways: by running extension cords directly from the generator’s outlets to your devices, or by connecting the generator to your home’s electrical panel through a transfer switch or interlock kit. The method you choose depends on what you need to power and how much you’re willing to spend on setup. Either way, the connection sequence matters for safety, and getting it wrong can damage your equipment or put lives at risk.
Choose Your Connection Method
For most people during a power outage, the simplest option is running heavy-duty extension cords from the generator to individual appliances. This works well for basics like a refrigerator, a few lights, and phone chargers. The limitation is that you can only power things with a standard plug. Anything hardwired to your electrical panel, like a furnace, well pump, water heater, or central air conditioner, won’t work with extension cords.
If you have a generator rated at 5,000 watts or more and want to power hardwired appliances or entire circuits, you need a transfer switch. Think of it as a miniature circuit breaker panel that draws electricity from your generator instead of the utility company. A licensed electrician installs a dedicated outdoor outlet (called a generator inlet box) on the side of your house, wired to the transfer switch inside. When the power goes out, you run a single cord from the generator to that inlet, then select which circuits to power from the switch. Budget $500 to $1,500 for the switch and installation, which typically takes less than a day.
A cheaper alternative is an interlock kit, which is a metal bracket installed on your existing breaker panel. It physically prevents the main utility breaker from being on at the same time as the generator breaker. You plug your generator into the same type of outdoor inlet, but it feeds your existing panel directly instead of a separate switch. Interlock kits cost $50 to $150 for the hardware, plus $400 to $800 for professional installation.
Why You Should Never Backfeed
Backfeeding means plugging a generator into a regular wall outlet using a double-male cord (sometimes called a “suicide cord”) to push power backward through your home’s wiring. This is extremely dangerous and illegal in most areas. Without a transfer switch or interlock to isolate your home from the grid, electricity from your generator travels back through the utility transformer and into the power lines outside your house. It steps up to thousands of volts and can electrocute utility workers repairing downed lines, as well as neighbors on the same transformer. It can also fry your electronics and appliances if utility power comes back on while the generator is still running.
Picking the Right Extension Cords
If you’re going the extension cord route, wire gauge matters. Extension cords are rated by AWG (American Wire Gauge), and the lower the number, the thicker the wire and the more power it can safely carry. For appliances drawing up to 13 amps, a 16-gauge cord works for runs up to 50 feet. For anything pulling 14 to 15 amps, like a power drill or larger appliance, step up to 14-gauge. High-draw devices at 16 to 20 amps need a 12-gauge or 10-gauge cord.
A few rules to follow: use only outdoor-rated cords, keep each cord fully uncoiled to prevent overheating, and don’t daisy-chain cords together. Give power-hungry appliances like space heaters and window air conditioners their own dedicated cord. An overloaded extension cord is a fire hazard.
Step-by-Step Startup and Connection
The order you do things in matters. Connecting appliances before the generator is running and stable can damage both the generator and your devices. Here’s the correct sequence:
- Position the generator. Place it outdoors on a dry, level surface at least 20 feet from any doors, windows, or vents. Point the exhaust away from the house.
- Check fuel and oil. Fill the tank and verify the oil level before starting. Use only the fuel and oil types your owner’s manual specifies.
- Start the engine with nothing connected. If the engine is cold, set the choke to the on position. Turn the fuel valve on, flip the generator’s power switch to “on,” and pull the starter cord firmly. You may need several pulls.
- Let it warm up. Once the engine catches, slowly move the choke back to the off position as the engine stabilizes. Give it a minute or two to settle into a steady rhythm.
- Connect your cords or transfer switch cable. Plug your extension cords or generator-to-inlet cord into the generator’s outlets. Then connect appliances one at a time, starting with the most essential.
- Add load gradually. Don’t plug everything in at once. Stagger connections to avoid overwhelming the generator with simultaneous startup surges.
When utility power returns, reverse the process: disconnect appliances first, then unplug the cord from the generator, then shut down the engine.
Managing Your Generator’s Load
Every generator has a maximum wattage rating, and you need to stay under it. The tricky part is that many appliances draw far more power when they first kick on than they do while running. A refrigerator uses about 700 watts while running but surges to around 2,200 watts at startup. A half-horsepower sump pump runs at 1,050 watts but needs 2,150 watts to start. A 12,000 BTU window air conditioner draws 3,250 running watts and nearly 4,000 watts at startup.
Add up the running wattage of everything you plan to power simultaneously, then make sure your generator can handle the highest single startup surge on top of that total. If your generator is rated at 5,000 watts and you’re already running 3,000 watts of appliances, turning on a refrigerator with a 2,200-watt surge will briefly push you to 5,200 watts and could trip the generator’s breaker or damage the engine. The practical solution is to stagger when things cycle on, and to be realistic about what you can run at the same time.
Weather and Placement Safety
Generators produce carbon monoxide, an odorless gas that kills hundreds of people in the U.S. every year. The 20-foot rule from doors, windows, and vents is a minimum, not a suggestion. Never run a generator in a garage, even with the door open, or in a basement, crawl space, or enclosed porch.
Water and generators don’t mix. Never operate a generator in rain, snow, or standing water, as the combination of electricity and moisture creates a serious shock and electrocution risk. If you need to run a generator during a storm, use a purpose-built generator tent or canopy that provides overhead cover while leaving all sides open for ventilation. A tarp rigged over the generator can work in a pinch, but it must not restrict airflow or contact the exhaust, which gets extremely hot.
Refueling Safely
Never add fuel to a generator while it’s running. Gasoline spilled on a hot engine or exhaust can ignite instantly. Shut the generator down and let it cool for 10 to 15 minutes before opening the fuel cap. Store gasoline in approved, clearly labeled fuel containers, and keep them away from the generator while it’s operating. If you’re using the generator for an extended outage, plan your refueling around natural breaks rather than waiting until the tank runs dry, which can damage the generator and anything connected to it.