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I have an electric dryer with a 30 amp circuit running to it. If I had a male-male plug to run from a portable generator to this outlet, would it be safe to run essential appliances (water pump, refridgerator, sump pump, etc) during a power outage as long as I tuned off the main breaker and the total draw was less than 30 amps?

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    This question needed to be asked because the accepted answer needs to be easy to find for the next person that considers doing it. – TomG Nov 17 '14 at 16:24
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    THIS IS MARKED AS A DUPLICATE, BUT THE OTHER ANSWER CLEARLY SUGGESTS GOING AHEAD AND USING THE DRYER OUTLET AND JUST "MAKE SURE YOU TURN OFF YOUR MAIN BREAKER." SO IT SEEMS LIKE A REALLY BAD ANSWER WITH SERIOUS REAL-WORLD PHYSICAL DANGER OR DEATH A LIKELY OUTCOME. THE ACCEPTED ANSWER ON THIS QUESTION IS NOT MERELY A DUPLICATE, IT IS THE ONLY CORRECT OF THE TWO ANSWERS. – Craig Nov 28 '14 at 21:17
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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.

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    Powering up the transformer that feeds your house is a really bad idea. An interlock system that disconnects the power feed (NOT MANUALLY FLIPPING THE 200A breaker) and connects the genset to the house system is mandatory. – Fiasco Labs Nov 17 '14 at 1:49
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    i thought this was what you should use for suicide – jsvnm Nov 17 '14 at 21:51
  • @jsvnm I was a bit concerned until I noticed the release date. – kasperd Nov 17 '14 at 22:27
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    @SpeedyPetey, this question was marked as a duplicate, but the accepted answer on the other question basically says go ahead and plug your generator into your dryer outlet. My point is that YOUR ANSWER IS THE ONLY CORRECT ANSWER OF THE TWO and there are potentially very serious real-life consequences for getting this one wrong. I copied your answer into an answer of my own over on that other question, and couldn't help expounding a little. DIY amateurism combined with electricity and over-confidence ought to scare the friggin' willies out of people. – Craig Nov 28 '14 at 21:21
  • Here's an example of what happens. – Watcom Nov 6 '15 at 15:44
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The transfer switch that MUST be used - as pointed out by Speedy - is essential that it be properly installed in conjunction with how the utility / house wiring is installed.

The transfer switch and interlock mechanism is essential for the safety of both you and for the utility folks that may be working on downed utility lines. With out a proper interlock and transfer switch your generator would be feeding out onto the mains lines and could very well kill someone. People who try to short cut and cheap out on installing a generator hookup correctly always think that they can remember to cut the main breaker before starting up their generator. But the plain fact that rules and regulations exist for use of transfer switches and interlocks proves that people make mistakes despite best intentions.

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    In addition to the hazards to the line-men trying to fix the outage, there is also the fact that, if you don't have your connection to the grid shut off, when the mains comes back online it will almost certainly not be in sync with your generator and you will be very lucky if tripping the breakers in question is the only damage done. Even with a transfer switch, a timing change like that can easily fry lots of your electronic devices. – Perkins Nov 18 '14 at 0:48
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    @Perkins - Not to mention the damage that could happen to the local generator if the full force of the utility line is fed right into the output of the generator. – Michael Karas Nov 18 '14 at 1:37
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I worked as a high voltage lineman for 30 years and have seen all kinds of squirrelly generator set ups. It is never a good idea to plug your generator into your home's wiring even if your turn your main off. NEC requires that a transfer switch be used. I have seen more than a few main breakers that had failed and were still on when they showed off. If you do not have a transfer switch, you risk sending power back through your breaker and meter, back to the transformer, and stepping 120 volts up to line voltage. No a good thing for the linemen out in the middle of the night, in bad weather, trying to restore everyone's power.

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I was told by an electrician that the mains breaker does not disconnect the neutral line, only the two halves of the 240 volt feed. Thus you are still connected to the grid.

A transfer switch will isolate everything.

  • In lots of the panels I've seen, the neutral line is attached to the local ground. Unless the generator is horribly miswired there shouldn't be any potential on it to the outside world, and if it is that badly miswired, you'll know when your house catches fire... That said, a proper transfer switch is still the proper choice. – Perkins Nov 18 '14 at 0:56
  • Well... yes the neutral is bonded to the ground bus, which should be bonded to a couple of 8' grounding rods driven into the soil outside your house, but is often bonded to water pipes (and you'll often find insulating corrosion on those old pipes at the point where the ground is bonded, or a rusty pipe underground), or in older homes not bonded to anything at all. In other words, the first path to local ground in those cases is the bare copper wire running from the transformer down the pole to a grounding rod installed by the utility company. So I wouldn't take anything for granted... – Craig Nov 28 '14 at 21:25
  • ...and there's still less electrical resistance back through that nice metal neutral path than there is into the dirt outside your house, and you're still physically connected to that neutral wire. So I would take nothing for granted. – Craig Nov 28 '14 at 21:28
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Can you? yes it is possible, it will probably even work. Is it a really bad idea, yes. Is it criminally illegal, probably not as long as you are sure to flip the breaker. Is it against code, yes. As others have said use an interlock, or if you need to do it cheaper, buy extension chords for your 3-4 critical appliances and use them.

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    It is most likely criminally illegal (depending on jurisdiction) for the reasons highlighted above. – Aron Nov 17 '14 at 17:26
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    @Aron Even if it's not illegal to do it, any damage to people/property caused by forgetting to open the main breaker would likely be classed as criminal negligence. – Perkins Nov 18 '14 at 0:52
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I have used a generator backing up through an "outlet" that I also use for welding for decades; that breaker is always off until it is needed for one operation or the other. I have marked every breaker that I want to run off the generator and turn off all the others along with the mains breaker. There is no problem, as long as you do that. Of course, I am the only person who is capable of hooking up the generator and running it, so there is no chance of someone else running into a problem. The only time an interlocking transfer switch is absolutely needed is if the generator automatically comes on when the power goes off.

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    This is wrong; don't do this. An isolating transfer switch and inlet receptacle is mandatory. Just because something works doesn't mean it's a good idea, especially with electricity. – friedo Nov 19 '14 at 22:03
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This is NEVER an option.

Sure it is. Done in farms across the land.

There is nothing inherently wrong with a male-male cord. It is obviously dangerous, but only to people dumb enough to wave the pointy end around while it is plugged into a live circuit.

Similarly, the transfer switch is for people who can't figure out how to turn the main breaker off. If you have a large (100 amp) generator in the garage it is a convenience.

You will not be re-energizing the electrical grid. Circuit breakers work in both directions, and the combined load of your neighbors plus the transformer will most certainly exceed the dryer's or generator's rating and trip a breaker.

Things you genuinely do have to be concerned about:

Dryers have 2 hots and a neutral. Does the generator provide 2 phases? If yes, great. If no, connect the red and black to the generator's live wire but also disable any 240v appliance, like a stove or air conditioner. Presumably the dryer is also disabled by virtue of it's plug being in use by the generator.

Welders are 240v only. Do not use a 3-pin welder plug for a generator - the absence of a neutral will have very strange results, like the hallway light only working when you turn on the toaster.

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    Honestly, man, this is just really bad advice. You know who can't figure out how to turn off the main breaker? The 12 year old farmer's son whose dad sends him on an errand to "turn off the main breaker and turn the generator on." Well, half the time he'll remember half the message. No snarky comebacks are needed here, I could tell you a half dozen stories of farm kids from families I knew who didn't make it to adulthood, or their fathers died when they were young, because of dumb*** accidents. But the point is human error is ALWAYS a factor. And doing this without an interlock is ridiculous. – Craig Nov 28 '14 at 21:31
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    ...now, no doubt, somebody is going to pipe up and say the farmer should be asking his 12 year old son to do something like that. Well, his visiting adult buddy or his wife would sooner or later do the same thing. And so will he. And it isn't the sort of thing that's going to electrocute the person starting the generator. In other words, I'm not advocating against farm kids doing useful stuff on the farm! The point is to never wire something together that intentionally creates the potential for this kind of mistake. – Craig Nov 28 '14 at 23:54
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    Fools are extremely ingenious people! Maybe the most ingenious! :-) Run a regular extension cord to your furnace. Job accomplished, you won't freeze. Convenience shouldn't be conflated with necessity. I guess if you have an all-electric furnace, or baseboard heat or in-floor or in-ceiling heat maybe that's a wrinkle. In that case, I'd say run extension cords to a few electric space heaters. Which really is a segue into a further issue. There's another post talking about a 6KW generator. At 120V, that's 50A, which is going to exceed the safe capacity of the wires feeding that dryer outlet. – Craig Nov 29 '14 at 5:41
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    fair enough, the circuit breaker on the dryer circuit may do the job even being on the opposite end of the circuit from the power source. The furnace has a simple 15A switch on it if it's a gas furnace. Is it harder to wire a cord in there than to create a suicide cord for the dryer receptacle? You keep saying smart people will be fine. You willing to bet your 4 year old's life that he's smart enough? DO NOT INTENTIONALLY CREATE SITUATIONS WHERE SIMPLE, PREDICTABLE HUMAN ERROR CAN COST LIVES. That's all I'm saying. Not to mention backfeeding your generator this way IS ILLEGAL. – Craig Nov 29 '14 at 11:55
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    as far as not having space heaters to run the extension cords to, you and I both know a lot of the people thinking about doing this didn't have generators until the storm warning was announced and they ran to Home Depot to buy a generator. So they may as well buy an interlock, too. And a couple of space heaters. And we're not talking about appliance circuits here, which can kill you. We're talking about a 30A 240V circuit, which will more likely kill you than just shock you. Your advice seems cavalier. Do you put your license plates on with bailing wire? Just curious... – Craig Nov 29 '14 at 12:15

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