Here’s specifically what’s wrong with using a male-to-male extension cord:
• Even people who think they know what they’re doing could get hurt or killed. For instance, do-it-yourselfers who use protective equipment for their home projects could wrongly assume that their protective gloves are sufficient to handle the plug, Sargent says. “The gloves are most likely not a properly voltage-rated garment,” he says. And people could trip over a male-to-male extension cord and expose the live end, leaving them and others vulnerable to shocks or electrocution. “We can’t guarantee how people are going to handle these out in the real world,” Sargent says. “It’s inherently unsafe.”
• They place utility workers at risk of shock and electrocution. Electricity fed by male-to-male extension cords can flow from the house back to the utility lines on your street and potentially shock or kill those essential workers. “Our workers, having every reason to believe they are working on ‘dead’ lines, would be exposed to this hazard,” says Allan Drury, a spokesperson for Con Edison, the New York City-based utility.
• They’re a fire hazard. If your generator is attached to your home and actively running at the same time that the municipal power comes back on, you’ve got electricity coming from two power sources at once, explains Misha Kollontai, the engineer who tests generators for Consumer Reports. “Two independent sources of power can create an overload on your electrical system,” he says. “Plus, your circuit breaker won’t protect you if you plug too much into the outlets on the same circuit as the generator. Either situation is likely to start a fire.”
• Your generator will probably get destroyed. When the municipal power comes back on, you also risk burning out your generator, Sargent says. “When there are competing sources of electricity, the power grid is going to burn out the internal workings of the generator,” he says. “You’re setting your generator up for failure.”
• You put your household at risk of carbon monoxide (CO) poisoning. The Consumer Product Safety Commission recently warned against the purchase, use, and sale of male-to-male extension cords, but highlighted a few it found on Amazon that were just a few feet long. A cord that short would require placing the generator very close to the house, which is dangerous, the CPSC stated. The odorless, colorless CO that portable generators produce is toxic and can kill within minutes. In fact, it kills about 85 Americans a year. That’s why the CPSC and Consumer Reports recommend placing a portable generator at least 20 feet outside a house, with the exhaust pointing away.