Thinking about getting a whole-home generator? Find a good place for it first!

In the U.S., we are VERY used to having electricity available in our homes at all times.  When an outage hits, depending on the duration, it can be a big deal!  About 33.9 million or 1 in 4 households nationwide reported they were completely without power at least once in the 12 months before they were interviewed for the 2023 American Housing Survey (AHS).  Approximately 70% or 23.6 million of the households reporting an outage said at least one outage lasted 6 hours or more. (About 1 in 4 Households Experienced a Power Outage in the Span of a Year)

Depending on the weather (if you’re not in the middle of extreme heat or cold), you may be able to tolerate a day without electricity.  Keeping the house closed up and the refrigerator and freezer closed will preserve your indoor climate and food for a number of hours.  However, sometimes our family members are frail and depend on critical equipment like air conditioners, oxygen concentrators or CPAP machines, so a back-up generator is more of a need than a want.  Whatever your reasons, here are some things to consider before purchasing and installing a generator. 

• Size and location:  Electrical appliances consume power in watts, and the “starting watts” of each appliance is higher than the “running watts”, accounting for that sudden burst of power needed to get a stationary motor running.  There are three main types of generators: portable, standby (or permanent), and inverter (a form of portable). 

• Portable generators (12 kilowatts or less) are mobile, must be located at least 20 feet from any occupied building and must be refilled with fuel and oil checked every so often.  The 20 foot rule is used to minimize CO intrusion and heat damage to the home, and it provides buffer space in case of accidents like fuel leaks or sparks. (How Far Should Portable Generators be From the House)  Check the runtime on the model you’re considering.  This generator buying guide lists some of the common appliances you can power with a portable generator.

• Inverter generators are a newer form of portable generators, known for their quieter noise levels, fuel efficiency and smaller size and weight.  Here is an excellent article about inverter generators, including their pros and cons.  You can usually connect two inverter generators together for twice the power.  

• Standby generators (more than 12 kilowatts) are larger and installed on a permanent foundation, are wired into your home’s electrical system and have their own fuel source. This guide is really helpful in calculating the watts you’ll need from a standby generator.  Although it costs the most, this type is the easiest to operate, as it is usually programmed to test-run once a week, and will switch on and off automatically via an automatic transfer switch in the case of a power outage.

• Noise: Usually, inverter generators will be the most quiet, however, newer versions of each type can be quiet.  Noise is a good thing to consider if you live in a townhome with a small backyard, and if you want to make a portable generator quieter, here is a video on how to make a safe sound-deadening enclosure for it, or another quick technique to drop the sound by 10 decibels.

• Fuel:  Different types of generators run on gasoline, propane, natural gas or diesel.  If you are looking to install a standby generator, you’ll also need to plan on where to install the fuel tank it will use.  

• Method of Connection to Power: For portable and inverter generators, extension cords are the normal way to get power from the unit to your appliances.  However, you need to make sure the extension cord is rated for the power you are drawing through it, otherwise it can heat up and catch fire.  In other words, if you plan on plugging several appliances into an extension cord running from the generator to the home, find out how many amps they are drawing, and make sure the extension cord is rated for the total amps.  Stagger the starting times of the appliances so there is not a surge of power running through the cord when they all start up together.   A standby generator is already permanently wired into your home’s circuit breakers, and the best connection includes an automatic transfer switch.  If you do not have an automatic transfer switch, you’ll need to make sure that you shut off power from the main electricity grid before switching on power from the generator. 

Now we REALLY want to emphasize the “location” choice of any generator.  Not only do these machines emit the normal gasoline engine exhaust, I just learned that gas generators also emit an unacceptable level of ethylene oxide (EtO, a toxic gas that is used to sterilize medical equipment and to manufacture many different products), a level that is 1.6 million times greater than the EPA’s risk factor for developing cancer from this gas.  Statistically speaking, it’s much more likely that one would be poisoned by carbon monoxide than develop cancer from exhaust entering the home over time, but neither are pleasant!  Therefore locating that standby generator– which will be automatically starting and running a 10-15 minute test cycle every week aside from emergency runs–-is very important.  

If you are considering adding a standby generator to your home, it’s important to first conduct a site survey with the licensed electrician who will be installing it (installation and connection of a standby generator is NOT a DIY job!).  In addition to measuring out the clearance from the home and its doors and windows, the electrician will also take note of:

• Prevailing winds (so that exhaust is directed away from the home), 

• Landscape features that would block exhaust

• Proximity to the existing electrical connection to power: as we mentioned before, the best configuration is to have an Automatic Transfer Switch installed between the generator and home, which prevents undesired flow of electricity from the generator into the main line or main line into the generator, and isolates the circuits in the house that you want to power. All other circuits are left without power to prevent overloading.  

• Foundation requirements: the generator needs a stable foundation because unlevel mounting will cause excessive vibration, noise, and even damage to the unit.

• Elevation: If your property is located in a flood zone, take a lesson from the hospitals and businesses that were hit by hurricane Katrina in 2005–if your generator is flooded, your home could be uninhabitable in the days and weeks following a major storm.  Make sure the foundation for the generator is not in an area where water will pool.  (Standby Generator Placement Requirements and Considerations)

• Fuel tank: Finally, the generator will need a source of fuel and proper placement of the propane or gasoline or diesel tank is essential too.  The site survey will allow the electrician to consider all of these things and give you a more accurate cost estimate for the job. (Your Complete Guide On Standby Generator Installation)  

From an air quality perspective, we want to make sure that harmful fumes from this large generator do not seep into your home.  For that reason, we advise the following:

• Air barriers can greatly reduce the amount of generator exhaust entering a home if the wind happens to be blowing the wrong way.  Therefore, if your home is older and there is no air barrier on the home, you may consider one of three options: 

• If it’s not too hard (as with vinyl siding, or board and batten siding), you could remove the house siding in that area and air-seal that wall/corner of your home.  This article details the location of where an air barrier should be located, depending on your climate zone. 

• Standby generators have an exhaust port on one side of their enclosure. Consider building a deflecting partition next to the port, to direct errant exhaust gases away from the side of your home.  It will need to be heat-resistant and have an airtight surface so that gases don’t permeate it.  You could use brick, with a metal surface like aluminum on one side (because brick is porous).

• Finally, just placing the generator a bit farther from the home will both reduce engine noise in the home and the possibility that exhaust gases will permeate it.

• Consider whether the generator will be located near a crawlspace.  Although the exhaust fumes are going to be hot and should rise into the atmosphere, if wind directs them underneath the home, they can accumulate and enter through a floor assembly that’s not sealed.  If this is a concern, a fan can be placed under the crawlspace area and wired to operate any time the generator is operation.

• If the generator runs off gasoline, the supply tank can produce gas vapors, which should be considered for its location. 

Having a standby generator is like an “insurance policy” that makes sense for many: get one if it helps you to be less concerned about losing power for an extended period of time.  By all means, though, do your own research on sizing, brands, fuel and placement, so that it will be a safe addition to your home.  

Photo by Jonas Gerlach on Unsplash