Can I backfeed a portable generator into my house's electrical system?
You know what, I'm going to repeat the answer found here to the same question. Here's that answer, short and sweet and to the point:

ABSOLUTELY NOT!! This is NEVER an option.

You MUST use some form of transfer switch or
interlock, along with the proper male inlet.
Also, a male-to-male cord is called a
"suicide cord" for a reason.


A transfer switch/interlock wired into your service panel is the ONLY LEGAL WAY to do this, and the only safe way.

Look, transfer switches.

Just a few expanded reasons not to do this include:


Check out this story, where backfeeding a generator like this started a fire that burned the generator, the neighbor's house, the neighbor's motorhome, the neighbor's race car hauler, a boat, and an SUV. Fun times, huh?
Check out this post, where a retired lineman talks about how many times he's seen broken main breakers that still let current through even when they were OFF. Yikes.
Backfeeding your generator into your dryer outlet is ILLEGAL, possibly criminally so, or at least totally open to civil prosecution. Tell me that an injury caused by you turning on your generator and feeding power back onto a damaged electrical grid where people are working to repair the lines, and into your neighbor's homes during a crisis won't be actionable? The NEC requires a transfer switch (and not for trivial or capricious reasons). That's good enough for me.
the "suicide cord":


Seriously, do you actually WANT a #10 extension cord energized with 240V/30A strung across your floor with energized metal prongs sticking out the end of it? What if it accidentally gets kicked out of the wall socket or something? A million things could go wrong. HORRIBLE idea.

You'll dump power (stepped up to at least 7,200 Volts by the transformer outside, so it'll go for miles and miles) on the power grid and electrocute a lineman doing repairs.


You, or more likely a spouse, visiting relative, or one of your kids, will forget to throw the main breaker before powering on the generator. Or one of your kids' rambunctious friends will fire up your generator when you're not looking, on some sunny July afternoon.
Guaranteed, especially since the generator will be needed seldom enough that nobody will remember the entire power-up checklist when the time comes.
The whole point of the transfer switch being an interlock is that it only physically permits a connection to one power source at a time.

You'll fry your generator and/or anything with electronics in your home:


When you've inevitably forgotten to throw the main breaker before powering up the generator, and you've been lucky enough not to have electrocuted a lineman, when the main power comes back on there's a good possibility it will backfeed into your equipment and cook it in one way or another (the timing of the 60Hz wave will be different, possibly amplifying the power to much higher levels, etc., other interesting possibilities).



If you do this, and none of the bad things happen to you, that's what we call blind dumb luck and you really shouldn't tempt fate like that more than once.  :-)

Don't do this. It's illegal and just a terrible idea--"Redneck" in the most uncomplimentary way.