Emergency Generators Great Source for Backup Power

Generators are a great source of backup power during an outage and this guide will help you find an emergency generator to suit your needs.

power outage

A good generator can help keep your home well-lit and cozy when the power supply from the grid is disrupted. 

Photo courtesy of Generac Power Systems

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A good emergency generator makes your home blackout proof. It’s relatively inexpensive insurance against complete loss of household power. Plus, portable units are convenient when you need electricity beyond the reach of an extension cord.

All generators combine an internal combustion engine with electrical components to create electricity for powering appliances and tools. Choosing an emergency generator involves several key decisions. How much power do you really need? How often do you expect to use it? Will it be for emergency backup power? For tools? Both? What level of quality makes sense? What kind of fuel? How will you get the power from the generator to items in your home?

More Power to You

The first thing to consider is generator output. What size is right for your situation? This sounds simpler than it really is because not all items on your wish list are going to be used all the time or at the same time. Also, some appliances (such as furnace fans, sump pumps, washing machines and refrigerators) require more start-up power than their specified ratings.

Generator output is measured in watts, a unit of power derived by multiplying electrical flow rate (amps) by electrical pressure (volts). One typical household outlet, for example, delivers a maximum of 1,800 watts (15 amps x 120 volts), or the equivalent of a small portable generator. Many people buy a small generator but regret it later because they didn’t understand the basic issues. I’m one of those people.

The backup generator I’ve used for the last 20 years has a maximum rated output of 3,500 watts. That seemed like enough when I bought it, but it’s proven barely adequate for emergency power. By the time the submersible well pump kicks in (1,500 watts at start-up), the basement freezer is running (800 watts) and a few lights are on (100 watts for several compact fluorescents), there’s not much power left for other things. If we want to use the microwave or toaster oven, we have to make sure that most other items are switched off. For sample wattage data for common appliances, see How Much is Enough?. (Guardian has an online calculator to estimate the size of generator that’s best for you. Visit Guardian and click “Which One Do I Need?”)

There’s also the issue of sustained output. When a manufacturer rates generator output, it usually refers to a maximum, short-term level only. In practice, most generators can sustain only 80 percent of their maximum rating for the long haul. If you continuously demand more than this, you’ll shorten the life of your investment. Unless stated otherwise, always consider advertised generator output as overly optimistic and apply the 80 percent rule.

Because of the reasons listed above, I’m planning to upgrade to at least a 5,000-watt gasoline generator. Unless you have particularly frugal power requirements, you’ll find this to be a good basic size. But there’s still more to know before you buy.

Watt’s Up with Start-up?

Any appliance with a motor — a refrigerator, circular saw, drill, water pump or furnace blower — creates what’s called an “inductive” electrical load. This means energy demand skyrockets for the first second or two after start-up. You should allow two or three times as many watts for start-up compared to watts required while running. Heating elements (in stoves, toasters or space heaters), lights and small motors don’t draw significantly more current on start-up. In cases where no wattage consumption figure is stamped on an item, use the “volts x amps = watts” formula. You’ll almost certainly find volt and amp numbers stamped somewhere on an appliance.

As you do the math, you may discover that you want more than 5,000 watts of backup power. If that’s the case, you should consider a stationary generator wired directly into your home’s electrical system. These units are covered by weatherproof shrouds and are ready to kick in either manually or automatically whenever the power goes off. Stationary units cost more than portables, but they deliver more power. Prices for units large enough to run multiple appliances and lights during a blackout range from about $3,000 to more than $10,000.

A Dirty Little Secret

The quality of power is important, too. Most generators create a specific frequency of alternating current (AC) by precisely governing motor speed — or at least they try to. But in reality, governor engine control is mechanical and pretty crude, especially on cheaper generators. That’s one reason generators typically produce such dirty (irregular) and potentially damaging AC power, filled with lots of high-voltage spikes. But the latest generation of “clean power” generators, often called inverters, takes a different approach.

These generators have a fuel economy feature that tailors engine output speed to electrical load demanded. Traditional generators run full blast, regardless of how much power you need. The engines on today’s best generators run only as fast as needed to create the power required. Switch on a light bulb, for instance, and the motor speeds up slightly from an idle. Plug in a 1,500-watt hot plate, and motor speed increases further to meet the electrical demand. It’s a smooth, quiet and economical system that’s easier on the environment. It also significantly reduces noise output.

At the other end of the spectrum are less expensive generators with basic engines, no-frills electronics and less than optimal mufflers. These are worth consideration if you’ll only be powering large, simple electrical items such as cooking appliances, water pumps or basic power tools.

So how do you tell the difference between premium-quality and economy generators? Engine design is one way. The most durable generator engines have overhead valves and commercial-duty chrome or cast-iron cylinder sleeves. Economy models have side valves and aluminum cylinders.

Prices reflect quality, too. Top of the line generators cost about two or three times as much as economy models for a given wattage output.

The Right Fuel

Regardless of the amount and quality of power you need, there’s also the question of fuel type. Most portable generators run on gasoline, but there are advantages to propane- and diesel-fueled models, too.

Propane (also called liquefied petroleum gas or LPG) is more expensive than other fuel options when you buy it in small tanks like those used with an outdoor grill. But it’s also more chemically stable than gasoline or diesel. Ordinary gasoline becomes significantly less flammable after several months of storage as key chemicals break down or evaporate. Diesel fuel also is susceptible to degradation by algae growth. You can expect two years of reliable shelf life by adding a conditioner to gas or diesel fuel, but LPG never goes stale, so an LPG system is worth considering if your generator will be used for emergency power only. But, understand that what you gain in fuel stability, you lose in generator portability.

Diesel engines are traditionally found only on large, stationary generators, but that’s starting to change. Smaller diesel systems in the 4,000-watt range are now appearing on the market. Diesel engines are harder to start and usually cost more than comparable gasoline motors, but they last longer, especially for continuous use.

Got a tractor? A whole range of PTO-powered (Power Take Off ) generators are available, most for medium and large power output. These units aren’t usually designed to put out the kind of clean (regular) power required by sensitive home electronics. Generator systems also can be installed onto engines in cars and trucks, either under the hood or attached to a PTO. It’s not always a simple installation, but it does offer relatively large power output, quiet operation and portability.

Keeping Fuel Fresh

Gasoline and diesel fuel are both perishable commodities. They simply don’t burn as well after several months of storage. So take precautions to be sure your generator will start and run reliably when an unexpected power outage occurs. There are two things to keep in mind: fuel preservation and fuel rotation.

Start by spending a few bucks on a gas or diesel fuel preservative. If you always add a measured amount of this liquid to stored fuel cans, your generator will fire up much more easily, even a year or two down the road. After adding a new batch of gas, run the engine long enough to draw the preserved gas into the carburetor.

Even with preservative added, get in the habit of rotating your fuel supply. I keep six 5-gallon cans full of stored gas at all times, though I make a point to use each can in my truck, tractor or lawn mower before the fuel is more than six months old. This way I always have relatively fresh gas on hand for the generator.

Power Delivery

There are two ways to get power from your generator to the place where you need it. Extension cords are easy to use, but limited. You have to run them from outside to indoors, and even then you can only energize items that have a plug-in cord. Powering the blower on your furnace, a household water pump or permanently installed lighting is out of the question. But if you have a generator that puts out 3,500 watts or more, it’s worth creating a connection directly to your household wiring so nearly everything requiring electricity in your home can be used (at least in theory). But there’s a catch: To be safe and legal, any such direct connection must pass through a transfer switch. This safety device ensures that either your home is connected to the grid or to your generator, but never to both at the same time.

While installing a transfer switch is a hassle (it involves splicing into the main cables feeding your house), it’s also a mandatory safety precaution to protect utility workers. If your generator happens to be feeding power into your home while your main breaker is still switched on, it’ll also deliver unexpected, phantom power to the utility lines. Work crews might have switched off incoming power to your area to complete work safely, but power from your generator would be hitting them from behind. For more safety tips, see “4 Generator Safety Tips” below.

Pure Power

Not all generator power is the same, and this is especially important if you plan to run electronics, entertainment equipment, battery chargers or computer hardware. Many generators aren’t made to power items like these at all. Use the wrong generator and it will create “dirty” power that could fry your electronics.

When it comes to electrical power, there are two kinds. Alternating current (AC) is what comes out of wall sockets in your home. Direct current (DC) comes primarily from batteries. But there are varying shades of gray between ideal AC and DC power. Until recently, most so-called AC generators weren’t producing anything like true AC at all. Instead of the smoothly flowing waves of rising and falling voltage required by sensitive items such as battery chargers, fax machines and computers, typical generators produce an erratic and jagged rendition of AC. And while this “dirty” AC power is OK for robust items such as fridges, hot plates and water pumps, it can destroy the sensitive electronics that most of us have come to rely on. You simply can’t plug everything into an average generator and expect it to survive. At the moment there’s no standard rating for the “cleanliness” of generator power. Just look for models that are specifically designed to run sensitive electronics and you’ll be fine.

Most of us live just one blackout away from the Stone Age, but this fact is easy to forget until the lights go out. We’ve all seen how vulnerable the electrical grid is to major weather events and overloads, and that’s the reason I like the security offered by a backup generator. Choose your equipment well, keep it in good shape, and it will provide peace of mind that you simply can’t get in any other way.

4 Generator Safety Tips

Generators offer great convenience during power outages, but if not used properly they are dangerous. Follow these guidelines for safe use:

  • Store gasoline outside your home — away from living quarters and livestock barns.
  • Always use a generator outside, never indoors or in an attached garage.
  • Protect a generator from rain and snow while stored and during use.
  • Use heavy-duty, outdoor-rated extension cords sized to match the power load and the length of the cord.

Oil Alert

Read the fine print in a generator owner’s manual and you’ll find that crankcase oil needs to be changed more often than you might guess. Details vary, but it’s not uncommon for oil changes to be required after every 24 hours of continuous operation. It’s easy to clock 12 to 18 hours of usage each day when you’re living through an extended power outage. That’s why you should keep fresh motor oil on hand. You’ll need to change the oil every couple of days during a long-term outage.

Contributing Editor Steve Maxwell has been helping people renovate, build and maintain their homes for more than two decades. “Canada’s Handiest Man” is an award-winning home improvement authority and woodworking expert. Contact him by visiting his website and the blog, Maxwell’s House. You also can follow him on Twitter, like him on Facebook and find him on . 

1/7/2016 6:43:08 PM

Automatic standby systems are becoming more and more essential. Backup home generators are great because they manage power for the whole house with a switch, or you can select critical loads and just focus on those needs with a pre-wired auto-transfer panel. The fact that they work with both propane or gas makes it appropriate for any home too. in Eugene, Oregon, we have a wealth of professionals like Balanced Electric, Inc (http://www.balanced-electric.com) which is comprised of a handful of electricians with over 20 years in the electrical industry. They offer free quotes, inspection, design, construction, installation, maintenance, etc. I like small businesses like that since they build a relationship with you and make sure you understand the mechanics of your generator(s).

12/17/2014 3:12:05 PM

The Guardian hyperlink goes to a login page. This address gets you to the calculator is: http://www.generac.com/for-homeowners/home-backup-power/build-your-generator

1/9/2009 9:13:41 AM

Teddi makes a good point, there are folks out there that have situations in which being without electricity for long periods of time could be dangerous or some of the older fashioned solutions might not be a good idea. I did not see where the author was stating that a generator is going to be used to keep every light in the house on while running 3 computers, 4 TV sets, a stove, washing machine and dryer, refrigerator and freezer all at the same time. The piece is about EMERGENCY *BACKUP* power. Relegating everyone with health problems to the center of large cities living next door to hospitals is irresponsible, ignorant and just plain silly. If someone needs something like CPAP (a treatment for obstructive sleep apnea) they are not to be sent off to live in a nursing home! It must be nice to live in such a black and white world of the healthy and capable versus the infirm. What a small minded world view. I thought Mother Earth News is about the principle that we ALL can do things to impact our world less. Some of us are able to live like Daniel Boone, and I applaud them, but some of us can only do the best we can by making the best choices we can, and being aware of the things that we do. It does not have to be one or the other: everyone can do SOMETHING, but not everyone can do EVERYTHING and there is nothing wrong with that. Mother helps us to learn about the "somethings" that we can do. Thank you.

1/7/2009 4:23:01 PM

I agree with Aaron. The idea behind living simply is using far less, if any, fossil fuels, and generators require petroleum fuels. How can Steve Maxwell be a "hard-core do-it-yourselfer" when he is depending on his generators to keep his lifestyle going? Does he have his own oil well and refining facility, to feed those generators? And Teddi, people with those kinds of severe medical needs, whose very lives depend on constant electricty powering their life support systems, should not be living anywhere off of the power grid but by a large city hospital who can take care of them.

2/4/2008 1:02:27 PM

I have a 7000watt generator. Can I disconnect my main circuit at the service panel and wire into my furnace and frig circuits safely. Thanks in advance for any replies.

chris thomason_1
2/4/2008 11:21:06 AM

I recently obtained one of the "Lister" type single cylinder slow speed diesel engines, and am going to try to find an appropriate generator head to build my own genset. These engines are one huge chunk of cast iron with a large flywheel, and are known to run constantly for decades with simple maintenance. There's a bunch of great info at www.utterpower.com Chris

1/3/2008 8:18:31 PM

I agree with Teddi. Our house uses baseboard hot water heat and last winter, a 2-day power outage brought our house down to below 50F. We were quite concerned about our pipes bursting and so will be installing a transfer switch to run the circulator off our generator if the power fails. We tried using our masonary fireplace, but those are actually negatively efficient in temperatures under 20F. Like it or not, modern households cannot survive without fossil fuel power (although we are on 100% green power from our electric company).

12/25/2007 1:23:10 PM

For Frank and some of the others... I try to be as green as possible. But in times of no power (which happens more in my area than I would like) We have started buying and using many of the new "crank power" flash lights and I even have a weather am/fm radio that uses the Crank power. We received a new "crank" lantern for our camper for Christmas today. There are many things you can get that help with out having to be dependent on electric to keep them going. We have been thinking of getting a generator to keep the fridge and freezer working and maybe the well. The other fun things, like the computer and tv can be put aside, and reading a good book never hurts. I do think that back up generators for the people who have medical needs should be researched and maybe be made more practical and economical.

12/23/2007 10:23:49 PM

I found this peice very informative. I do have a querry though. The article mentioned "dirty ac would destroy electronics", would that include a radio such as a boom box/CD player? And I think everyone should think about thier own situation and prepare for that.

12/23/2007 10:09:34 PM

Aaron makes a valid point and when an outage occurs, I'm OK with not using the electric range or refrigerator but I won't give up my Central Air! I can't do without it in the summer. Good article. Jim

12/23/2007 8:52:02 PM

In response to the above comment... I am glad Mother Earth news posted this article. It is very timely, and discusses what is already available in an emergency. Who has time to research what the best generator is when they're already literally freezing in the dark? For many people living frugally with oil lamps, hard labor, and firewood just isn't possible. Small children and oil lamps... hmmmm. Not everyone has a chimney or a woodstove and can breath smoke. Think of those with medical needs like oxygen (which is flammable), nebulizer and sleep apnea machines, or those who are electric wheelchair dependent and need power to get around. Electricity means survival for many, and what if they can't get to a shelter because the phone is out and they have no vehicle? Disaster preparedness means having a backup source of power and could mean life or death for some to go without. By the way, in many of the winter storm areas, I don't know that solar back up power would be adequate with all the snow, freezing rain and ice and cloud cover. PROVE THAT IT WOULD BE!!! Would you have to shovel snow off, or scrape your solar panels with an ice scraper to get it clear, and risk breaking a hip? My point is, using fossil fuels for an EMERGENCY is sometimes necessary. Also, whoever said 'Mother Earth News' was only for those who live in rural areas? I plan on getting some laying hens for my garden for fresh eggs and bug control, even though I live 5 minutes from the mall outside city limits. Not every one who wants to improve and care for the environment can afford to live in the country. Those who want to live frugally probably already are.

12/23/2007 11:37:32 AM

I thought that this article would make a lot of sense in a rural living publication. However coming from Mother Earth news I was amazed. Wouldn't an ecologically focused article mention CONSERVING? USING LESS? ALTERNATIVE FUEL? Whenever I've had an electrical problem we use antique oil lamps (which are easy to find) and use a solar battery unit for limited power. We don't use microwaves or washing machines. We do most tasks by hand. Imagine, just like people did before electricity was common. When a disaster strikes, this is an opportunity. An opportunity to connect with natural living and to practice consuming less. I invite you to research intelligent systems which don't depend on fossil fuels (which are actually causing most of these disasters).