Quick answer: Home generators come in two broad types: portable units you roll out and start during an outage, and permanently installed standby units that start on their own. Either one must connect to house wiring only through a transfer switch or an approved interlock, never by backfeeding through an outlet. Carbon monoxide is the other major hazard, so portable generators must run outdoors, well away from doors, windows and vents.
Storms that bring down limbs and lines, winter ice on the plateau, and the occasional long outage after severe weather lead many households in the Chattanooga area to think about backup power. A generator can keep a refrigerator cold, a well pump running, a sump pump working or a medical device powered.
The generator itself is only half of the decision. How it connects to the home's electrical system determines whether it is safe for your family, your neighbors and the line workers trying to restore power.
Portable and standby generators compared
- Portable generators are moved into place and started by hand when the power goes out. They usually power a limited set of circuits or appliances and need refueling during longer outages.
- Standby generators are permanently mounted outside on a pad, connected to a fuel supply, and paired with an automatic transfer switch. They start on their own after an outage and can be sized to run part or all of the home.
- Inverter-style portable units produce cleaner power and run more quietly, which can matter for electronics, but they tend to have lower output.
The right fit depends on what you need to keep running, how long outages typically last where you live, fuel availability and how much hands-on effort you are comfortable with during a storm.
Transfer switches and interlocks
A generator must never be able to send power out to the utility lines. Two common methods prevent that.
A transfer switch is a separate device that moves selected circuits, or the whole house, from utility power to generator power. With an automatic transfer switch, this happens on its own when utility power drops and switches back when it returns. Manual transfer switches require you to flip the selection yourself.
An interlock is a mechanical plate installed on the main panel that physically prevents the main breaker and the generator breaker from being on at the same time. Paired with a properly installed generator inlet, it lets a portable unit power chosen circuits through the panel. Interlocks must be approved for the specific panel.
Why backfeeding is never acceptable
Backfeeding means plugging a generator into a household outlet, often a dryer or range receptacle, using a cord with two male ends. It is sometimes called a suicide cord for good reason.
- It can energize the utility lines outside your home, putting line workers and neighbors at risk of electrocution.
- The exposed prongs on the cord are live when the generator runs.
- It bypasses the protection built into your panel and can overload wiring and start a fire.
- When utility power returns, it can damage the generator and wiring, or cause a fire.
If you already have a generator but no safe way to connect it, run appliances on heavy-duty outdoor extension cords plugged directly into the generator until a proper inlet and transfer method can be installed.
Carbon monoxide and fuel safety
Generator exhaust contains carbon monoxide, a gas you cannot see or smell. It can build to dangerous levels within minutes in enclosed or partly enclosed spaces.
- Run portable generators outdoors only, never in a garage, basement, crawl space or porch, even with doors open.
- Place the unit well away from doors, windows and vents, with the exhaust pointed away from the house.
- Install and test battery or battery-backup CO alarms on every level and near sleeping areas.
- Let the generator cool before refueling, and store fuel in approved containers away from living spaces.
Sizing: what you want to keep running
Rather than starting with a generator size, start with a list. Decide which loads truly matter during an outage, then let an electrician estimate the running and starting demand.
List essentials
Refrigerator, freezer, well pump, sump pump, furnace blower, some lights, phone charging and any medical equipment.
Add comfort loads
Heat pump or air conditioning, water heater, range and laundry if you want them.
Account for starting surge
Motors and compressors draw more power for a moment when they start.
Match to a connection method
A short list may suit a portable unit and interlock; a whole-house goal points toward standby equipment.
If you already have backup power but some circuits stay dark, the page on a generator that runs but leaves parts of the house without power covers common causes.
Planning with an electrician
An electrician offering generator hookup and installation can evaluate your panel, recommend a transfer method, install the inlet and pull any required permit. If the panel is older or crowded, an electrical panel upgrade may come first. Standby units also involve fuel and placement rules, so coordination with other trades is common.
