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March 27, 2017

Whole-house generator installation tips

Aurora Diesel Generator Installation

Where to Install Whole-House Generators

There were another two articles on the web this weekend pertaining to fires started by people using generators to power their home.  Here are some whole-house generator installation tips.

The first article appears to be about a propane whole-house generator which was mounted directly adjacent to a home in Swansea MA. Flames spread from the generator housing to vinyl siding, then moving to the interior of the home. Though the owner had not moved into the home yet, there were workers present who escaped unharmed.

Home burned due to faulty propane generator.

Home burned due to faulty propane generator. Herald News Photo-Michael Holtzman

The second report is from Sandy Utah where gasoline powered generators were housed in a shed attached to the home.  It appears one of the home occupants refilled a portable generator and when he restarted the generator, the fuel refill can caught fire.

The Upshot

Auxiliary whole-home generators must be installed and used in a safe fashion.

It is never safe to use a gasoline generator in an enclosed attached structure.  Not only are they not designed for this application, but the refueling and carbon monoxide dangers are real and significant.

Auxiliary generators are best installed away from living structures.

 Regardless of fuel source, they are electromechanical appliances with the potential for failure.  A generator pad 15-20 feet from the living structure not only lowers the noise level perceived inside the home, but offers an added measure of safety should a catastrophic malfunction occur.  The added cost? Maybe 20 feet of copper power supply line.

Carbon Monoxide

Distance reduces the chances of habitation poisoning by carbon monoxide.

Carbon monoxide is a colorless and odorless gas. It is particularly pernicious, because most victims don’t realize they are being poisoned until it’s too late.
“Every year, at least 430 people die in the U. S. from accidental CO poisoning. Approximately 50,000 people in the U.S. visit the emergency department each year due to accidental CO poisoning. You can take steps to help protect yourself and your household from CO poisoning. Change the batteries in your CO detector every six months. If you don’t have a battery-powered or battery back-up CO detector, buy one soon.
“The most common symptoms of CO poisoning are headache, dizziness, weakness, nausea, vomiting, chest pain, and confusion. People who are sleeping or who have been drinking alcohol can die from CO poisoning before ever having symptoms.” (Center for Disease Control)
In an attempt to keep a generator dry (or prevent theft), some people place their generators in their garages or underneath porches where carbon monoxide can slowly seep into the home and become concentrated.  It is foolish to take this risk.  Even with an open garage door or porch, CO can migrate into the dwelling.
“Portable, gasoline-powered generators are a common source of unintentional CO poisoning after power outages. The devices are used increasingly to provide electricity during temporary outages resulting from adverse weather events, but the CO produced during their operation can be a serious health hazard. The exhaust produced by the typical 5.5 kW generator contains as much CO as that of six idling automobiles. When used indoors or in close proximity to residential dwellings, this exhaust can quickly infiltrate living spaces and incapacitate occupants.”  (Carbon Monoxide Poisoning from Hurricane-Associated Use of Portable Generators — Florida, 2004)

“New research from the National Institute of Standards and Technology (NIST) shows that to prevent potentially dangerous levels of carbon monoxide, users may need to keep generators farther from the house than previously believed—perhaps as much as 25 feet.

“Up to half of the incidents of non-fatal carbon monoxide (CO) poisoning reported in the 2004 and 2005 hurricane seasons involved generators run within 7 feet of the home, according to the U.S. Centers for Disease Control and Prevention (CDC).

“Carbon monoxide can enter a house through a number of airflow paths, such as a door or window left open to accommodate the extension cord that brings power from the generator into the house. While some guidance recommends 10 feet from open windows as a safe operating distance, NIST researcher Steven Emmerich says the “safe” operating distance depends on the house, the weather conditions and the unit. A generator’s carbon monoxide output is usually higher than an automobile’s, he says, because most generators do not have the sophisticated emission controls that cars do.

“We found that for the house modeled in this study,” researcher Leon Wang says, “a generator position 15 feet away from open windows was not far enough to prevent carbon monoxide entry into the house.

“Winds perpendicular to the open window resulted in more carbon monoxide entry than winds at an angle, and lower wind speeds generally allowed more carbon monoxide in the house. “Slow, stagnant wind seems to be the worst case because it leads to the carbon monoxide lingering by the windows,” Wang explains. Researchers determined that placing the generator outside of the airflow recirculation regions near the open windows reduced carbon monoxide entry.  (National Institute of Standards and Technology)

As with any other major appliance, whole-house generators must be used with common sense.  Become familiar with the safety criteria associated with powered equipment before you need to use that equipment.

Diesel vs. Gasoline vs. Liquid Petroleum/Natural Gas

From the articles above, one can discern two potential safety issues with auxiliary generators:  Carbon monoxide and refueling.

Fuel: Combustible or flammable?

Flammable liquids have a flash point of less than 100°F and combustible liquids have a flash point at or above 100°F.   The rate at which a liquid produces flammable vapors depends upon its vapor pressure, so liquids with lower flash points ignite easier.  Fuel will not ignite unless it is a vapor, because the vapor burns, not the liquid itself.   With a flash point of 52 C (125 F), diesel will not ignite until it is heated to a vapor.  Gasoline, on the other hand, has a flash point of -43 C (-45 F), which makes it flammable at room temperature.
When it’s in a puddle, a match will not heat diesel fuel sufficiently to burn.  Obviously, gasoline and gaseous fuels will ignite readily when uncontained.
So, is diesel safer than gasoline, natural gas or LP? Due to the higher flash point I think so.  But, as with all fuels, care must be exercised with storage and refueling.
If you expect to run your generator for extended periods of time, it makes sense to look at a separate fuel storage/delivery system which negates the need to manually refuel a hot generator.  Similarly, be aware of the risk associated with pooling vapors from spilled gasoline or LP leaks.  Also, periodically have your LP/NG generator stall fuel cutoff feature tested. This safety device turns off the supply of fuel when the generator speed falls below a certain threshold.
Generator installed away from house

Covered generator installation.

The photo here shows an Aurora Generator installation that is off the house.  Note that there is no enclosure to capture fumes or impair cooling.  The metal roof keeps snow and light rainfall off the equipment.  IMO, this is a good clean installation!  😉

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