Key takeaways:
- In some cases, a portable generator (5,000 to 7,000 watts) can be enough to power essential equipment during an outage.
- However, many Middle Tennessee households can benefit from a standby generator with more capacity.
- The best generator depends on what you need to power during an outage. An electrician can recommend the ideal generator capacity after doing a load calculation.
How big of a generator does your Middle Tennessee home really need?
For many homes, a 5,000-to-7,000-watt portable generator can power a few essential appliances, but you might want to invest in a standby generator with more capacity to keep your HVAC running or have a more reliable solution in place for medical equipment.
Read on to learn more about how to properly size your generator if you’re planning a generator installation.
Portable Vs. Standby Generators
Before going any further, you should ask yourself if a portable or a standby generator would be a better match for you.
| Generator Type | Typical Capacity | Best For | How It Connects |
| 5,000 to 7,000 watts | Essential loads, occasional outages, budget-friendly backup power solution | Extension cords or a professionally installed manual transfer switch or interlock kit | |
| 10,000 to 14,000 watts is common, with higher capacity system reaching 18,000 to 24,000 watts and above. | Automatic backup power solution, expanded essentials, including HVAC systems | Permanently hardwired with a transfer switch and fuel connection |
Portable Generators
Portable generators are typically the more affordable option. They use an onboard fuel tank, usually gasoline, although dual-fuel models may also run on propane.
You can plug appliances directly into a portable generator using properly rated cords, but many homeowners prefer a safer and more convenient setup: an electrician-installed manual transfer switch or panel-specific interlock kit. This allows the generator to power selected home circuits without running extension cords throughout the house.
Portable generators must always operate outdoors, away from doors, windows, vents, garages, crawlspaces, and enclosed areas. Never connect a generator directly to a wall outlet or “backfeed” a home electrical panel. A properly installed transfer switch or interlock protects your home, utility workers, and generator equipment.
Standby Generators or Whole-Home Generators
A standby generator is permanently installed outside the home. It connects to a fuel source, often natural gas or propane, and to the electrical system through an automatic transfer switch.
When utility power fails, the transfer switch detects the outage, starts the generator, and transfers power to the home. When utility power returns, the system transfers the home back to utility service and shuts down the generator.
Standby systems cost more upfront, but they’re a great solution for homeowners who want automatic backup power, more circuits covered, or protection for systems such as central HVAC, well pumps, sump pumps, refrigeration, medical equipment, and security systems.
How Much Power Do Common Household Appliances Use?
To give you a better idea of how much generator capacity you need, it helps to know how much power common appliances use.
Here are a few estimates:
|
Appliance or device
|
Approximate running watts
|
| Coffee maker | About 900 watts |
| Microwave | About 1,500 watts |
| Electric cooking range | About 1,500 to 2,000 watts, depending on elements in use |
| Electric water heater | About 4,500 watts |
| Window AC unit | About 1,000 to 1,500 watts |
| Television | About 100 to 200 watts |
| Computer | About 40 watts |
| CPAP machine | About 30 to 60 watts for standard use, up to 100 watts with heated humidification or heated tubing |
| Ductless mini-split | Roughly 600 to 3,000 watts per zone |
| Central HVAC | Often 2,000 to 5,000+ running watts, depending on the system |
The biggest challenge usually comes from large appliances and equipment with motors or compressors. Central air conditioners, heat pumps, refrigerator compressors, well pumps, furnace blowers, sump pumps, and septic pumps can all create a high electrical demand, especially when starting.
What Size Generator Is Best for Your Middle Tennessee Home?
Rather than buying a generator based on the size of your house, think about the level of backup power you want during an outage.
Basic essentials: 5,000–7,000 watts
A 5,000- to 7,000-watt portable generator is often enough for a basic emergency plan. It may support:
- Refrigerator and freezer
- LED lighting
- Phone chargers and small electronics
- Wi-Fi router and modem
- Television
- CPAP machine or other lower-wattage medical equipment
- Selected outlets
- Sump pump, depending on the pump’s starting demand
- Microwave or coffee maker, used one at a time
This range is ideal if you want to preserve food, stay connected, run medical equipment, and maintain a few basic comforts. You’ll have to do some basic load management, for instance, by not running your microwave and coffee maker at the same time.
Expanded essentials: 7,500–10,000 watts
A larger portable generator or smaller standby system can support a more comfortable outage experience. Depending on the home and the generator’s surge capacity, this range may cover:
- Essential loads listed above
- A furnace blower or air handler
- More kitchen circuits
- A garage door opener
- A small window air conditioner
- A larger sump pump or well pump
- Additional lighting, outlets, or refrigeration
- A small ductless mini-split in some situations
This range may work well for homeowners who want more than bare-minimum backup but do not necessarily need the entire home powered.
Whole-home or near-whole-home backup: 14,000–24,000+ watts
A larger standby generator is usually the better choice for households that want broad coverage and automatic operation. These larger backup power systems can support:
- More of the home’s lighting and receptacle circuits
- Multiple refrigerators or freezers
- Central HVAC, depending on the equipment and load-management plan
- Well pumps, septic pumps, sump pumps, and other large motor loads
- Kitchen appliances
- Medical equipment
- Security systems and communications
- Select electric appliances
However, a whole-home backup solution can’t necessarily power all your appliances at the same time. Electric water heaters, electric dryers, ovens, ranges, space heaters, EV chargers, and HVAC equipment can quickly add up. Your standby system may use load management to prioritize essential circuits or prevent multiple high-demand appliances from starting at once.
What Should You Power First During a Middle Tennessee Outage?
In Tennessee, outages can happen during severe thunderstorms, high winds, humid winter weather, or periods of intense summertime heat. The systems you want to back up first may change from season to season.
Summer Outage Priorities
During a hot-weather outage, many homeowners prioritize:
- Refrigerators and freezers
- Fans
- A window AC unit or selected cooling zone
- Dehumidification
- Internet and phone charging
- Medical equipment
- Sump pumps, if heavy rain is also a concern
Running a full AC system is possible with a standby generator, and a soft-start device can help lower the drain on your generator when your AC starts.
Winter Outage Priorities
During a cold-weather outage, you may want to prioritize:
- Furnace blower or heat-pump air handler
- Refrigeration
- Lighting
- Internet and phone charging
- Medical equipment
- Sump pump or sewage-ejector pump
- Well pump, where applicable
If your home has a gas furnace, remember that the furnace still needs electricity to operate its controls and blower motor. Electric space heaters can be an alternative if your generator is properly sized for them, but keep in mind that space heaters use about 1,500 watts and can quickly deplete your fuel reserve.
Other Important Loads
Depending on your household, you may also need to plan for:
- Well pumps
- Septic pumps
- Sump pumps
- Security systems
- Garage door openers
- Home-office equipment
- Internet and cellular charging
- Aquarium equipment
- Refrigerated medications
- CPAP machines, oxygen concentrators, or other medical equipment
Running Watts Vs. Starting Watts
When sizing your generator, you need to account for running and starting watts:
- Running watts are the continuous amount of power an appliance needs while operating normally. A refrigerator, for example, may use a relatively modest amount of electricity while its compressor is running.
- Starting watts, sometimes called surge watts, are the extra burst of electricity needed to start motor-driven equipment. This can apply to central AC units, heat pumps, furnace blowers, refrigerators, sump pumps, well pumps, power tools, and more.
A generator may be able to provide a higher peak or surge-watt rating for a short period, while its running-watt rating represents the amount of continuous power it can safely supply.
A basic sizing approach is to add the running watts of the loads you plan to operate, then account for the largest starting surge that may occur.
Why You Should Not Size a Generator Too Close to Its Limit
It may be tempting to choose the smallest generator that appears to cover your estimated load. However, running a generator near maximum capacity for long periods is not ideal.
A generator with some extra capacity can provide important benefits:
- Less strain on the engine and electrical components
- Lower risk of overloads when appliances cycle on
- Better ability to handle startup surges
- More flexibility to use an additional appliance when needed
- Potentially better fuel efficiency at a moderate load
- Less wear and a lower likelihood of nuisance shutdowns or repairs
Ideally, your generator should operate within 50% to 80% of its total capacity.
How an Electrician Can Help Size Your Generator
A local electrician can help you figure out what size generator is best for you. They’ll help you create a backup-power plan and go through the following:
- Reviewing your electrical panel and available capacity
- Identifying the circuits you want to power
- Checking appliance nameplates and equipment specifications
- Measuring or estimating running watts and starting watts
- Identifying high-demand motor loads
- Reviewing HVAC equipment, well pumps, sump pumps, septic systems, and other major loads
- Determining whether a portable or standby solution makes the most sense
- Recommending a manual transfer switch, interlock kit, or automatic transfer switch
- Discussing propane, natural gas, gasoline, or other fuel options
- Evaluating generator placement, permits, wiring, and maintenance needs
- Considering load management or a soft starter for HVAC equipment
You’ll get a customized recommendation for generator sizing that is based on the things you need to power during an outage.
Schedule Your Generator Consultation With Airstream Services HVAC, Electrical & Plumbing
Airstream Services HVAC, Electrical & Plumbing has been serving Middle Tennessee since 2012. As a local generator installer, we can help you choose the backup power solution that’s best for your home.
We always start with a home assessment and a load calculation. We can then recommend the right generator for your need and plan a safe and code-compliant installation from there.
You can book a generator assessment online to get started or give us a call at 615-216-5979.
FAQ
What size generator do I need for my home in Middle Tennessee?
It depends on what you want to power during an outage. A 5,000-to-7,000-watt portable generator can often handle basic essentials, but a standby generator may be a better match if you’re looking to power more equipment.
Is a 5,000-watt generator enough to run a house?
A 5,000-watt generator is usually enough for selected essentials, but not the entire home. It may power a refrigerator, freezer, lighting, Wi-Fi, phone chargers, a TV, a CPAP machine, and a few small appliances or outlets.
What size generator do I need to run a furnace?
Many larger portable generators and standby systems can support a furnace blower along with essential circuits. However, the blower may have a higher starting demand, so it should be included in a generator load calculation.
Can I power medical equipment with a generator?
A properly sized generator can power many types of medical equipment, including CPAP machines, oxygen concentrators, refrigerated medications, mobility equipment chargers, and other essential devices. However, do not rely on a generator without first confirming the equipment’s wattage requirements and any manufacturer recommendations.
What is the difference between running watts and starting watts?
Running watts are the continuous power an appliance needs while operating normally. Starting watts, or surge watts, are the extra burst of power that some equipment needs for a few seconds when it turns on.
Why do I need extra generator capacity?
Buying a generator that only barely covers your estimated load can lead to overloads, unexpected shutdowns, reduced fuel efficiency, and added wear on the equipment. Extra capacity gives the generator room to handle startup surges and changing household loads.
