When the power goes out, a generator can keep your house warm (or cool), your kitchen cooking, and your computers and phones charging.
A permanently installed home backup generator protects your home automatically. It runs on natural gas or liquid propane (LP) fuel, and sits outside just like a central air conditioning unit. A home backup generator delivers power directly to your home’s electrical system, backing up your entire home or just the most essential items.
Standby generators are rated by kilowatts, which basically measures the machine's strength and endurance.
Typically you will pick a standby generator and an automatic transfer switch in a bundled package. Below are some useful tips to guide you in your generator and transfer switch selection.
1. Standby Generator & Central AC
First, you need to decide if you want to power your central air conditioner during a blackout. In the southern states, life can be miserable during a sweltering summer blackout. Northerners might be willing to sacrifice the air conditioner to save some dough.If you want to run your central air conditioner, you need a strong generator capable of turning over a high-powered motor. If you skimp on strength, don't expect it to start.To size your central air conditioner, simply take a good look at its metal data plate. It will tell you either its Tons, BTUs or Amps.
Where to Find a Data Plate on an Air Conditioner If the label is missing, check out your main circuit panel, most air conditioners use either a 30-Amp, 40-Amp or 50-Amp double-pole circuit breaker. The size of the breaker is typically a great indicator to the size of your air conditioner.
For example, if you have a 4-ton (or 48,000 BTU) air conditioner, you'll need at least a 17-kilowatt generator.
Generator / Central Air Conditioner Sizing Chart
2. Endurance
Electric Breaker PanelYou're buying a standby generator to replace the electricity lost from the utility company.If your electrical panel has a 200-amp main breaker, the maximum amount of electricity your home can consume is 200 amps. If you have 100-amp service, it's 100-amps.
Let's be honest. You're never using the maximum amount of electricity. Your consumption is somewhere between 0 and your maximum.Do you really need a massive 200-amp generator? In most cases, no. You don't use that much electricity in the first place.
How to choose an Automatic Transfer Switch:
Next is the transfer switch,
A standby generator is basically brain dead without an automatic transfer switch.
They are similar to the thermostat in your house. Instead of monitoring temperature, an automatic transfer switch monitors utility power.
When the power goes out, the automatic transfer switch tells the generator to start.
1. Select a Size
200 amp main breakerAutomatic transfer switches come in a variety of amps, ranging from 50-amps to 400-amps. In most cases, you simply match the transfer switch to the main breaker in your electrical panel. For example, if you have a 200-amp main breaker, you'll need a 200-amp automatic transfer switch.
2. Select a Style
Automatic Transfer Switches come in one of three styles:
Standard Switches
These prehistoric automatic transfer switches are usually custom ordered by older electricians who love installing unnecessary sub-panels. Standard automatic transfer switches are rarely bundled with home standby generators any more. Stay away if possible.
Load Centers
Instead of installing an automatic transfer switch AND a sub-panel, most manufacturers combine the best of both worlds into a single switch.
Load centers are ideal for standby generators powering small homes with 100-amp inbound service. Your electrician simply connects the load center to 8-16 mission critical circuits.
Unless you own a really small home, you’ll still experience a mini-blackout with a load center. When a high-demand appliance – like a central air conditioner – turns off, the extra electricity generated cannot be diverted to other circuits.
Service Disconnect
If 16 circuits just aren’t enough, you can opt for an automatic transfer switch with service entrance disconnect, which energizes your entire electrical panel. They are best suited for larger generators powering homes with 200-amp service.
Your electrician installs it between your meter and electrical panel. While their initial cost is usually greater than a load center, you don’t need to purchase a sub-panel. Plus, they are typically easier to install than a load center.
Pros
Natural gas is readily available in almost every location, and the new shale reserves opened up by fracking techniques mean a virtually limitless supply. Because natural gas lines are run to the site of operation, these generators never run out of fuel or need to be refilled. This also means that the generators are not portable.Natural gas generators burn cleanly with very little waste, and the gas is readily available even in the absence of a power supply. These units are also affordable in comparison to other choices. Natural gas also starts well in cold conditions, and runs relatively quietly.
Cons
The disadvantages of natural gas generators include higher installation costs, due to running the gas lines. These generators do not typically last as long as diesel generators, and if the gas lines are broken this could lead to a dangerous leak. Like propane, there is no issue with "wet stacking" when operating a natural gas generator.
Pros
Propane boasts a longer shelf life than gasoline or diesel fuels, and burns far cleaner. It is easily stored in any quantity, and is readily available even during power outages. Propane produces relatively low emissions, and is not subject to "wet stacking" common in diesel generators. Propane generators are generally affordable, and last a long time. Propane also starts easily in cold temperatures, and offers quiet operation.
Cons
On the con side, propane is kept under pressure, and is highly flammable, even explosive. The fuel systems are more complex, therefore subject to failures that are more frequent. Installation costs are higher, because a qualified technician must install the gas lines. Propane generators are more expensive to buy and operate, burning about three times the amount of fuel as comparable diesel engines. Additionally, propane units typically do not have long life expectancies compared to some other generator types.
Pros
Of all the options on the list, gasoline generators are among the most common, primarily because gasoline is readily available and these generators are on the low-end of the cost scale. However, gasoline is usually unavailable during power outages, because it requires electricity to pump. Gasoline generators are available in small sizes, ideal for portable models, but the fuel is highly flammable. Start well in colder temperatures.
Cons
Gasoline lasts less than one year when stored, and gas prices are comparatively higher than diesel, propane, and natural gas. Gasoline generators produce relatively high emissions, do not typically last as long as some other models.
Pros
Diesel is the least flammable of all the fuel sources, and is almost as readily available as gasoline. These engines have long lifespans, and perform more efficiently while lasting longer under heavy, rigorous use, so long as they are properly maintained. Diesel generators are affordable to operate, though these units typically cost more than gas generators. Some states, counties, and municipalities allow farm operations to purchase diesel at a reduced tax rate, or without tax levies at all.
Cons
However, diesel fuel is only good up to 24 months in storage, and storing large quantities can be expensive. Like gas, it's often impossible to pump diesel during power outages. Because diesel engine emissions are quite high, some areas limit the number of hours these engines can be operated per day due to environmental concerns.Moisture in the fuel ruins it (unless it is emulsified diesel, discussed below), so it is not well suited to wet environments, such as those near lakes and rivers or outdoors in the elements. Diesel generators require regular maintenance by a qualified mechanic, and are heavier engines, therefore less portable. Additionally, diesel generators start poorly in cold environments.
Stationary power generators typically run on natural gas or propane.
• These units cost more money and should be installed by a pro (so factor in labor costs). An experienced electrician can help with town or municipal permits, noise restrictions, and proper location.
• These start automatically when the power goes out, and often supply more power.
• They run a self-diagnosis and let you know when maintenance is needed. Some even do this via email or text, to you or your dealer.
• You have your choice of fuel—natural gas or propane, both of which are less risky to store than gasoline.
• They range from roughly 5,000 to 20,000 watts.
• They cost from $5,000 to $10,000.
These Generators are typically rated from 5KW to 20KW.
Portable Generators can run on Gas, Diesel, Biodiesel,or hydrogen.
• These units tend to cost less.
• They run on gas or propane that you may need to store in large quantities. Stabilizer must be added to store gasoline safely.
• You can use them anywhere on or off your property, but they must be at least 15 feet away from your house, doors, or windows—and not in an enclosed space. If it's raining, you must use a tent or cover.
• Several of these models offer electric starting. The battery required, however, may not be included.
• They provide from 3,000 to 8,500 watts.
• They cost from $400 to $1,000.