Estimated reading time: 10 minutes
It’s Complicated, But It Can Be Done.
Most of us who own generators for backup electric power for our homes do the usual thing. We run some extension cords from the generator into the house connected to a power strip or two. One extension cord usually runs into the kitchen to power the refrigerator and the other cord to the living room or family room to give us some light at night.
That kind of setup usually gets us through the usual power outage with a duration of a day or two at the most. But it’s when an outage extends into a week or more or when outages happen with any frequency that the extension cord solutions start to wear a little thin.
Another alternative is to run a large gauge extension cord directly into the house with a dedicated power strip or more, but it still requires a lot of improvisation and does little to help run hard-wired equipment like furnaces, well pumps, and other appliances and equipment that aren’t simply “plugged in.”
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A Whole House Solution
The idea of using a generator to provide emergency power to the whole house is nothing new.
Companies like Generac sell generators that tie into a home’s electric panel to provide emergency power to everything. It’s a good solution, but it’s expensive and requires professional installation.
If you don’t have the budget nor inclination to hire a contractor for a whole-house power backup, you could connect a large generator to your home’s system yourself, but it’s a complex project requiring some significant electrical engineering.
If you’re considering a whole-house power solution, we’ll try to give you links to resources and equipment in this article to guide that decision. Take a good look and then stop and think about if this is something you want to pursue.
Generators 101
Generators come in a variety of sizes and configurations. The most common generators are gas powered. Smaller generators have a 1-galllon tank while the larger generators usually have 5-gallon gas tanks. If you’re planning to connect a generator to your home you want a 5-gallon tank that will at least get you through the night.
There are also generators that are powered by dual fuels. These generators will run on either gasoline or propane. Propane powers a generator longer than gasoline and is generally safer to store.
However, the most significant measure of a generator is its output measured in watts.
Watt Ranges
Gas-powered generators produce wattage in ranges from 900 to 12,000 watts and up. The smaller wattage generators are usually used recreationally for camping or to power tools for construction at remote locations. Generators that deliver wattage from 5,000 to 12,000 watts are better suited to whole-house power generation.
One thing to look for is a generator with a 240 Volt outlet. Many only have a 120-volt outlet and for a whole house hookup, you need 240 volts. Look for a generator that meets your needs in terms of watts and has both 120 and 240-volt outlets. The 240-volt outlets have 3 prongs in a circular pattern like you would see behind a stove or oven.
How Many Watts Do You Need
The easiest way to assess wattage needs is to do an audit of your fixtures, appliances, and equipment that will be drawing power from your generator. You’ll need to make a list of all electrical fixtures and appliances in your home and add up the total wattage. You could also calculate this generally using square footage. You could also look at your breaker box panel to calculate your home’s current electrical draw.
Remember that some equipment like well pumps, sump pumps, and furnaces have something called a “power draw or startup.” A power draw at startup is when an electric motor needs more power to get started and then draws less once it's running. Well pumps and sump pumps can sometimes draw an additional 1,000 watts just to get up and running and then level off at a lower amount of watts.
Check your owner’s manual on larger equipment or Google it to determine power draw and add it to your total. It’s unrealistic to think that you would be drawing wattage for everything in your home at one time, but take a hard look at your list and think about worst-case scenarios where you may be using multiple electrical appliances or equipment at the same time.
You should also make sure you practice some level of power conservation when you’re dependent on your generator for power. A Sense Energy monitor can help and we’ll cover that later.
A Word of Caution
If you have no experience working with electricity or wiring, don’t do this yourself. Hire an electrician. If you can’t afford an electrician, try to find a friend or family member who is an electrician or has a lot of experience with electricity. They may also shake their head and say, “Don’t do this.”
If you do have experience working with electricity, do your homework. This isn’t as simple as fixing a light switch or running a new outlet in the garage. You’re essentially going to be installing new breakers and other equipment like power transfer switches beyond the range of basic wiring. If you want a peek at what’s involved with a project like this, there are videos on the Internet that will give you an idea.
Critical Success Factors
In addition to having sufficient wattage for your power needs, there are other factors that will make or break a whole house connection.
- An Interlock or Transfer switch
You want any generator power delivered to your home independent of any power provided by your local utility. The power may be out because of a storm or other event, but it often comes back on without notice. If that happens while you're delivering power from a generator, the power surge could cause a number of significant problems from destroying appliances and equipment to a fire or even spreading the surge to your neighbors.
You need a shutoff or interlock switch to allow your self-generated power to be delivered independently. This is sometimes referred to as a transfer switch or interlock switch. When the power comes back on, you then shut down your generator and shut off that system before flipping the switch back to utility-generated power.
Some transfer switches and interlock switches are designed to work automatically. Most require you to manually shut down one system before switching to the other system.
- Generator Power Cord
The cord that connects your generator to your new power system needs to be capable of carrying and delivering high wattage and volts. You can’t use a standard extension cord to power the whole house. It could literally melt or ignite.
- Heavy Gauge Wire
There will be some wiring involved. Use heavy 10 gauge wire. This is mostly for wiring around your breakers.
- Grounding
Grounding is a standard practice with electricity and you need to think about grounding your home powered setup. It’s maybe the simplest process step and the basic grounding supplies can be found on the Internet.
A generator should be grounded whether you’re using it only to plug in a couple of extension cords or for a whole house hookup. If grounding for the whole house, the ground wire should run from the breaker box or electric panel.
- A “Sense Energy” Monitor
This is a monitor you attach to your two main power cables in your breaker box to sense the amount of energy you are using at any given time. It can help you manage your power usage and know when to conserve power and when you have power in reserve.
- Local Codes and Inspections
Many parts of the country have strict local codes for any significant rewiring or electrical work. We may have done our share of DIY electrical repairs with ceiling lights and outlets but doing work in a breaker box will need to adhere to local codes. The reason is that it’s a potential source for severe short-circuits, fire, or even electrocution.
This kind of work usually requires an inspection as well. That actually may be a good idea if you’re not an electrician. An inspection can seem a bit nerve-wracking, but at least you’ll know the installation was done properly and if not, you’ll sure know what to do to get it right.
Putting it All Together
Before you get started, do as much as you can to research the critical steps for installing a whole-house generation system. How much research you do depends on your level of experience working with electricity. You’ll also need tools for electrical work and safety gear, particularly protective gloves and eye protection. It’s reassuring to know you have a backup for electric power in an emergency, just don’t let the installation become the emergency.
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