Portable generators have new safety features
Test engineer Dave Trezza sets up a portable generator inside CR's new carbon monoxide safety test chamber.

Consumer Reports is revamping its ratings of portable generators to reward models that implement new safety features—and to penalize those that don’t. Now, only three of 20 models earn a spot on CR’s list of recommended products.

From 2005 to 2017, more than 900 people died of carbon monoxide (CO) poisoning while using portable generators, according to the most recent data from the Consumer Product Safety Commission (CPSC). These machines, which produce reserve power, have long been under scrutiny from safety advocates. A single portable generator emits hundreds of times more carbon monoxide than an idling car, and consumers may not be aware of the hazard posed by the deadly gas, which is colorless, odorless, and tasteless.

To reduce the risk of carbon monoxide poisoning, some new generators feature a built-in sensor that triggers an automatic shutoff if CO builds up to dangerous levels in an enclosed space, and some also have engines that emit less CO in the first place. Recent CR test data show that these safety features are likely to save lives.

“We believe safety technology is critical for portable generators, and as an organization we can no longer recommend any model that doesn’t have some form of it,” says Liam McCormack, CR’s vice president of research, testing and insights. “We’re incentivizing the industry to move in the right direction, as we have in the past with innovative life-saving features on cars, such as electronic stability control, which is now standard. The goal is to achieve broad adoption of effective generator safety technology, as we believe every consumer should have access to safe products.”

Generator Safety Technology at Work
Here's a simulation of CO emissions from two different portable generators building up in an enclosed space. One has an automatic CO shutoff, and one does not.
Auto Shutoff
No Shutoff
PPM = Parts per million
By Andy Bergmann

CR recently tested five new portable generators with an automatic shutoff, and all five passed our new CO safety technology test, shutting down before carbon monoxide reached specified limits in our enclosed space. Three models also did well enough in our performance tests to earn a CR recommendation: the 7,000-watt Ryobi RY907022F, $1,165; the 8,000-watt DeWalt PMC168000, $1,050; and the 8,000-watt Generac 7675, $1,050. They all have the capacity to power the essentials in a typical home, save for central A/C.

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Two models, from Champion and Craftsman, got a boost to their Overall Score by passing the CO safety test but didn’t perform well enough otherwise to earn a CR recommendation.

Twenty models in our ratings that lack the technology saw a drop in their Overall Score, and all 14 previously recommended models lost that status. (For more details, see our portable generators ratings.) CR's CO safety technology test does not apply to home standby generators, permanently installed machines that typically are subject to local building codes.

CR's Findings

Our test results confirm that an automatic shutoff can prevent a generator from producing deadly levels of carbon monoxide in an enclosed space. In about 93 percent of the deaths reported to the CPSC, the generator was placed inside the victim's living space. 

But our findings also reveal potentially life-threatening gaps that the automatic shutoff fails to address. When we ran an experiment simulating someone using a portable generator at the threshold of their garage, with the door open for ventilation but the exhaust directed inward—something people could do without recognizing the hazard—all five generators failed to shut off as levels of CO quickly built up to unsafe levels. That's why it’s critical for consumers to follow safety guidelines with any generator (see graphic below), in particular directing the exhaust away from living quarters.

“This new class of generators represents a big first step, and we want manufacturers to push the technology even further,” says Don Huber, CR’s director of product safety. “Based on our test results and analysis of death and injury data, we believe it is both feasible and necessary for manufacturers to install safety measures that limit carbon monoxide exposure on all their portable generators.”

Portable generators with safety features began appearing in fall 2018. Now there are more than a dozen models on the market, and our experts expect to see many more in the near future.

The generators are all between 4,000 watts and 8,000 watts, and range in price from $600 to $1,150. You might see marketing terms such as “CO Guard,” “CO Protect,” “CO Detect,” “CO Shield,” or “CO Sense.” The way to verify whether a generator meets one of the two standards is to look for one of these references on the packaging:

• ANSI/UL2201 Certified for Carbon Monoxide Safety.
• ANSI/PGMA G300 Certified Safety & Performance.

CR tests both types the same way.

How to Run a Generator Safely

How CR Tests Portable Generators for Safety

Our new safety technology test is scored pass/fail based on two factors: whether a portable generator has an automatic CO shutoff feature and whether it shuts off in an enclosed space before the gas builds up to levels specified in the applicable standard. (Note that CR tests products for the purpose of comparison, not compliance with any standard.) A model with a shutoff that works passes the test, earning a rating of Excellent; a model without a shutoff fails, earning a rating of Poor—disqualifying it from CR’s list of recommended products. And if we were to test a model with an automatic shutoff that didn’t work, it, too, would earn a rating of Poor.

In order to conduct tests safely in an enclosed space, we bought a 20x8x8-foot shipping container and hauled it onto the grounds of our headquarters in Yonkers, N.Y. We cut off one end and replaced it with a garage door to allow for various simulations, then outfitted it with laboratory-grade carbon monoxide sensors to record levels of the gas in different sections of the 1,280-cubic-foot enclosure. “The idea is to capture readings from the entire space,” says Dave Trezza, CR’s test engineer in charge of the project. “Carbon monoxide is a gas and doesn’t build up uniformly throughout.”

Trezza and his team ran each of the five new models with various loads to simulate different ways a consumer may use the product. (The higher the load, the more fuel the engine burns, the higher the CO emissions.) They collected data on time, temperature, humidity, and CO levels throughout the test, and monitored for outside factors such as wind and temperature. All five models aced our test—shutting down well before the limits set out in the applicable standards.

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Each of the two standards specifies a peak level and a lower level for sustained exposure. That’s because carbon monoxide’s effects on human physiology depend on the level and how long you’re exposed to it.

Symptoms like headaches and dizziness generally occur at CO levels from 70 to 150 parts per million (ppm), which a typical generator can produce in minutes. You can die from sustained levels above 150 to 200 ppm, according to the CPSC's safety guide on carbon monoxide. And if you survive a high-level exposure, you could be left with brain damage. 

According to emergency room data we obtained from the CPSC, an estimated 15,400 people were treated in the ER for carbon monoxide poisoning tied to a generator from 2005 to 2017. 

As an emergency room physician in hurricane-battered Florida, David Farcy, M.D., is on the front lines of this safety issue. “Carbon monoxide is called the silent killer not only because it’s undetectable by the senses but because of the sequence in which it kills you,” he says. Farcy is president of the American Academy of Emergency Medicine. “While lower level exposure might make you feel sick, at higher levels it can incapacitate you, not unlike excessive drinking,” he says. “Many people fall asleep completely, shortly before dying from the effects of the gas.”

In our testing, although all of the generators shut off well below their maximum threshold for CO, the results reveal differences in how the safety features work, based on which standard a generator meets.

A Tale of Two Standards

One standard was created by the Portable Generator Manufacturers’ Association (PGMA), a trade group, and approved by the American National Standards Institute (ANSI). For a generator to meet the PGMA standard, it must have a shutoff mechanism that automatically stops its engine before carbon monoxide reaches 800 ppm or if the average exceeds 400 ppm over any 10-minute period. “Our standard came about after a review of CPSC data that showed nearly all deaths associated with carbon monoxide from generators occurred in enclosed spaces or indoors,” says Joe Harding, technical director at PGMA. “It’s been tested in thousands of simulations and is designed to protect consumers and prevent nearly all of deaths.” 

In our tests, the four generators that claim to meet the PGMA standard shut down well before CO levels in our container hit the specified limit of 800 ppm.

Generator Safety Standards
Under both the PGMA and UL standards, an automatic shutoff kicks in if CO, measured in parts per million, reaches a certain limit, or if the average exceeds a lower limit over any 10-minute period.

The other safety standard comes from UL, which sets and certifies consumer product safety standards (you’ve probably seen the UL mark on household items, such as smoke detectors and power cords). For a generator to meet the UL 2201 carbon monoxide safety standard, in addition to an automatic shutoff, its engine must significantly reduce carbon monoxide emissions. The shutoff levels in the UL standard are lower than PGMA’s: a 150 ppm average across any 10-minute period or a peak of 400 ppm. It’s a belt-and-suspenders approach that so far has been adopted only by Techtronic Industries (TTI), which makes brands including Ryobi.

Michael Gardner, TTI’s vice president of new product development, says the company’s rationale is based on a broad view of the risk. “Our review of the data led us to believe that after a hurricane, many people are running a generator for 24 hours a day—and often in close proximity to the house to prevent it from being stolen,” he says. “That realization led us to conclude we needed to develop generators that addressed the perils of outdoor use, too. And that automatic CO shutoffs alone weren’t enough.” 

Of the models we tested, only the Ryobi claims to meet the UL standard, and it shut down before well before CO reached the specified limits. 

The CPSC is reviewing data on both standards to consider whether compliance with either, or some combination of the two, will adequately protect consumers. In the meantime, because the standards are voluntary, it’s entirely up to manufacturers whether to comply with one or the other standard—or neither.

TTI's Gardner told CR that going forward all of its new generators will be equipped with one or more safety features designed to mitigate the risk of CO poisoning. Generac told CR that it has introduced nine new models with an automatic CO shutoff. “Generac is committed to the safety of all portable generator users,” says Ryan Schmitt, Generac’s product manager for portable generators and accessories.

CR's safety advocates believe having two separate standards is not ideal.

“Manufacturers now have two voluntary safety standards intended to help reduce the CO hazard,” says William Wallace, manager of home and safety policy for Consumer Reports. “Ultimately, to best protect consumers, there should be a single, stronger standard enforced by the Consumer Product Safety Commission.”

Survival Mode

For many people, generators are emergency equipment used under duress, during power outages. They’re just trying to keep their families safe. The desperate nature of the circumstances makes it difficult to predict how people might use—or misuse—a generator.

Indeed, the data on generator deaths is anything but uniform. In one-third of the cases for which the CPSC has data, the agency has found that consumers who die from using a generator indoors had made some attempt to vent the exhaust outside: cracking open a window, opening a garage door, or even attempting to carry out exhaust with custom-made ductwork.

All of this helped inform some of the experimental testing that CR conducted, such as the simulation of someone running a generator near the door of the garage, with the door open for ventilation but the exhaust inadvertently directed inside.

“It’s foreseeable that a homeowner could end up using a generator in an attached garage with the garage door in the open position,” says John Galeotafiore, an associate testing director at CR. “After all, a generator shouldn’t get wet, yet power outages often occur during rain or snowstorms. If a person doesn’t have a canopy to protect their specific generator, we can imagine why he might think it’s safe to run it near an open garage door. Our results show it is definitely not safe.” 

According to our results, this is a scenario in which a low-CO engine could give a homeowner who makes a mistake a fighting chance. In our experiment, though the automatic shutoff features failed to kick in on any of the generators, the Ryobi, with it’s low-CO engine, had notably different results. In this limited trial, carbon monoxide did not reach life-threatening levels.

“Since we’ve evaluated only five models with CO safety technology and only one of these had both a CO shutoff and low-CO emissions, it is too early for Consumer Reports to say one standard is more effective than another,” says Maria Rerecich, CR’s senior director of product testing. “But we certainly support any effort to reduce the amount of CO emissions produced by portable generators.”

CR will continue to evaluate models tested to either of the two standards as they come on the market. In the meantime, whichever generator you use, follow this critical safety guidance: Always place it 20 feet away from your home or any other structure, with the exhaust directed away from the structure.

CR members with digital access can read on for ratings and reviews of the only portable generators in our tests that blend enhanced safety and superb performance. 

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