By Mike Sokol
Dear Mike,
After being caught at home (Texas) with no electricity during a winter storm, I got to thinking about how I could hook up my RV generator to power my house. I didn’t think of it in time or I would have given it a trial. My RV stays in my RV barn with a 50-amp hookup. This RV does not have an automatic change-over relay. So I wonder if I had just started the generator and left the power cord plugged into the 50 amp circuit would it have powered my house? I thought this might be one to ask you as I have never seen this mentioned before. What do you think? —Jack D.
Dear Jack,
That’s an interesting idea that I’ve been asked about a number of times, and I casually thought it would be possible with the right kind of home inlet and transfer switch. But now that you’ve asked, I’ve done a deep dive into how installed RV generators are connected. Since I already know all the nuances of how pedestals are wired and what you have to do to use ANY generator to power your house, all I have to do is figure out how the power works for a Cummins-Onan generator.
Take me out to the ball game…
Since it will soon be baseball season, let’s warm up the batter and see how we do at the plate. No, I was never a baseball player. Well, except for a when I was playing in a shale pit less than a mile from my house, a short bike ride away.
Strike 1 – Swing and a miss… with original RV generator idea
Okay, I know for sure that your initial idea won’t work at all, even though it’s been proposed by other readers. It certainly has a big enough shore power cord that one would “think” the power would go both ways. However, it only flows from the house pedestal outlet to the RV shore power inlet. Not the other way around.
Take a look at a typical 50-amp shore power cord as an example. The male plug that connects to your pedestal is an inlet ONLY. The female twist-lock connector is an outlet ONLY. So back-feeding from the RV to the house with this shore power cord won’t work.
Ball 1 – Low and inside…
So I thought about adding a 50-amp female outlet on the side of a typical Cummins-Onan generator that would be found in most RVs. And while it looks like it could work at first, looking at the schematics reveals that RV generators are all wired as two separate legs of in-phase 120-volt power. Therefore, this is NOT the 120/240-volt split phase you need to power your house.
So the sad fact is there’s no practical (or even code compliant) way to wire an outlet on your RV that would plug your Cummins-Onan generator into your house electrical system. Drat!!!
Strike 2 – Foul ball
To top it off, to use any kind of generator to power your house you would first need to add some sort of generator interlock or transfer switch. The type that would be accepted by your local AHJ (Authority Having Jurisdiction / Electrical Inspector) varies from state-to-state and county-to-county.
But I do know that in all cases you would need to mount a male twist-lock inlet on the side of your house and a separate generator panel or lockout breaker to your house service panel.
Strike 3 – Yer out!
Of course, any of these fixes would need to be done when there’s no emergency occurring. So don’t plan on calling for an electrician to hook this up for you the next time it snows in Texas.
If you do want to consider generator power for your house, the time to install it is during the summer. I did exactly this for my dad’s house two years ago. I bought a portable Honda EU7000i generator which can power everything in the house. And even my smaller EU3000is generator can power most of his 120-volt appliances at the same time.
In an emergency, even my Honda EU2200is would work to power a lot of the important things that need electricity in the winter such as my boiler furnace, WiFi connections, computer, and lights, but no air conditioners.
Put me in, coach….
So, yes, if you have a portable inverter generator already (like this EU3000 or a pair of EU2000is generators), you could definitely install a generator inlet on your house with the appropriate transfer switch or circuit breaker lockout.
Then the next time you lose power, simply grab your generator out of storage and hook it up to your generator inlet on the house. Make sure it’s at least 20 feet away from any open windows. You can run it for a week or more on a few 5-gallon gasoline containers (depending on how big of a generator you have).
Don’t strike out next time … with your RV generator
If you all would like, I’ll plan on a future article this summer showing how a generator inlet and transfer switch/lockout is done to code. Yes, you’ll have to pull a permit and get it inspected, but at least you’ll know that it will work safely if there’s another blizzard that takes out the electrical grid.
Don’t strike out… And remember – Failing to plan is planning to fail.
Let’s play (ball) safe out there….
Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.
For information on how to support RVelectricity and No~Shock~Zone articles, seminars and videos, please click the I Like Mike Campaign.
##RVT992
We are building a lakeside cabin and wanted to be able to use the RV generator (Onan QG7000) to power some 120V circuits (fridge, Lights, ceiling fans). Considering having a sub panel (with manual transfer switch) for those loads. I understand there could be a neutral current issue because differences between the utility and RV 120V characteristics. Is there a safe (code compliant) way to wire those loads to sub panel?
There’s a ways and legally to hook up our rv to a house.
Some houses don’t require to 220
Easiest solution is to just move into the RV until power is restored. C’mon hun, lets go RVing the driveway!
Can’t do that in a winterized RV that isn’t built for the 0 degree temps we got here in DFW.
I ran an extension cord into the house and ran my gas furnace to warm the house up, then I ran the fridge for a while. Worked like a champ.
My last house I wired a 30 amp single phase outlet to my panel. Had to turn the main breaker off to use. When I sold the house I disconnected it. Never had to use. Many people did similar, but is unsafe and dangerous if not careful. The house I bought, the panel was a unsafe Federal panel. Had it replace with a panel designed for generator use. It had a setup so when you flip a lever it shut off the power line to the pole and turns on the generator power. When the power come back on from the pole a led light comes on to let you know. Than you just turn the lever in reverse. Only used it once. As soon as I got it set up and running power came on. Mike Sokol will only tell you the correct and safe way to hook up any electric. According to the National Electric Code.
I always figured that if we had a long term power outage I could 1. Pull the main breaker in the house. 2 run a couple of extension cords. One extension cord to the Refrig and if necessary, connect the gas furnace blower power to an extension cord also from the RV Generator. Those two items are the only critical items. BUT since I have my own Roof solar it might just be best to isolate the house, run off solar by shutting down all unnecessary appliances. This would work as long as my roof panels are not snow covered and the Sun is up.
If you pull the main breakers in the house, you should be isolated from the power lines.
If you are running the generator, your RV power transfer switch will have you isolated from the pedestal power connection, but pull the plug anyway.
At this point you can run contractor cords to freezer / refrigerator from different breakers in the RV. And a 3rd cord for multiple low power items, like a light, computer, router, TV, USB chargers.
Then turn off breakers for everything else except fuel furnace. Then run a heavy duty male-male (dangerous) cord from an (outside?) unpowered house outlet to the (outside?) powered RV outlet. The power goes from the RV (outside?) outlet to the house (outside?) outlet to the breaker box, so you will be limited to that total amount of current, then the power distributes via the main connector wires to the other breakers on that phase.
In addition to a really dangerous power cord with two male ends, I think you will only be powering one bus on your main panel with 120 volts but if any of your 240 volt appliances come on (like the stove or furnace) you will be back-feeding the other bus at a reduced voltage which will be really bad for some appliances and electronics.
Everyone…. NEVER use a male-to-male “Suicide Cord” to back-feed power from any generator into your house electrical system. It’s a huge code violation, very dangerous (as in it can get you killed) and could give your insurance company a reason not to pay a claim. If you need to run your refrigerator and furnace from your RV generator, the only simple and safe option would be to use a heavy-duty extension cord from your RV directly to you refrigerator and furnace controller (you’ll need to install a male plug on your furnace AC supply).
Now is a good time to evaluate your own emergency power needs, so I’ll do an extended article and video on emergency power hookup soon. In the meantime, please keep safe around electricity.
When there’s been massive power failures in our small town in Florida in the past, the rescue squads and firefighters tend to make out like bandits. People show up at the stations with thawing freezer contents and barbque grills.
Hey Mike, I looked into this a while back and was told not to do it since feeding Electricity from a generator to the house could back feed out of the house, up the line and potentially kill a lineman close by, working on the lines. The best solution is to use extension cords to run the Refrigerator, the Furnace & a light.
We were in Houston for the Big Freeze. Thank God, I had a full tank of diesel to run my generator. I will now fill my tank before the RV park instead of when we leave. The power was out for 18 hours initially and then sporadically after that for a week.
My guess is that when the power was turned back on it surged and burned out the charge side of my Xantrex Freedom 458 inverter charger. I ran the gen all night to power the furnace and keep warm as it got down to 16 degrees the first night. When I awoke the next morning My house Bats were at 6.5V. I am thinking I should have unplugged my shore power cord to avoid this. Note to self, power goes out, unplug cord
There is a switch to prevent back feeding power out of your home.
Huh?
I’m totally confused. My portable generator puts out 120/240 volts. Is a onan different. My onan emarald only puts out 120 volts and this I understand but the big 7-10 kw diesels don’t put out 120/240?
Without a transfer switch in the house to isolate the power co service , sombodys gonna get killed.. Best advice, tell someone to hire a QUALIFIED electrician and until then, use an extension cord to the needed appliances.
The outlets at an rv park provide 120/240 single phase power
That’s correct, that big Cummins-Onan generator in your RV is most likely wired with dual 120/120-volt outputs.
Right on the mark Thomas, During these commercial power outages, the most important thing to remember is that there are many men and women working in horrendous conditions trying to restore your power. They have families to go home to when their job is finished. Any alteration which can feed power to the AC distribution panel in your home can put their life at risk. Use a qualified electrician installing the proper equipment acquiring the proper permits and finally inspected. Don’t risk other people’s lives for your convenience.
Otherwise run an extension cord into your home and plug those appliances directly into the cord.
I live in Montana and weather is always a concern, even in the “summer” months. My house was already wired for a generator by the previous owner and we have yet to hook up our generator to it. However, I also built a waterproof bug-out box that has a MPPT charge controller for our solar panels, a 1000w pure sine inverter, quick-disconnect Anderson plugs for a bank of batteries, waterproof 120v outlets, and built-in cooling fans. This box can be used with my 400w wind turbine or solar panels mounted just off my back porch, or can be used with the roof-mounted solar panels on the RV when boondocking. Obviously, the generator would be the easiest option, but if the noise or lack of fuel becomes a problem, the box will do nicely!
I learned something new. I assumed since the Onan generator in my 50A coach had two outputs it produced 220V, even though we had no use for 220V. So, I guess you could still run some discrete 15A extension cords from your RV into your critical appliances in an emergency.
Yes, you can certainly run a few 15-amp extension cords from the RV to your house, but there’s no practical way to create a 50-amp 120/240-volt split phase output from a Cummins-Onan Generator in an RV.
There was some strange code back in NFPA 1192/94 that somehow didn’t allow onboard RV generators to be wired as 120/240-volt, split-phase. Seems ill-advised since any 50-amp shore power cord is wired for 120/240-volt, split-phase. All I know is, every Cummins-Onan RV generator schematic I could find is wired as dual 120-volt outputs that are in-phase. So yes, you could cobble together a 30-amp output from one of the generator legs, but there’s no way to get 240-volt power from it into your house to run 240-volt appliances.
Now, if zombies were attacking I know a way to do this, but it’s expensive, dangerous and a code violation. So let me know when zombies attack and I’ll show you how to do it. Until then this in a non-workable solution.
Take the meter off and clip your 2 110v heavy duty alligator jaws to the appropriate lugs….you have 220 again! 😀 …or, go to your main- turn off the breaker and clip in. Don’t do either unless you are comfortable and know the hazards before hand.
Drew, that’s incorrect and dangerous. Your RV generator does not produce 120/240-volt split-phase power, and you certainly don’t want to connect this into your meter socket. Remember, two legs of in-phase power has additive neutral currents rather than subtractive. Plus none of your home 240-volt appliances will power up (electric water heater, submersible well pump, heat pumps, electric range/oven, etc…). I really need to write some extended articles about this.
You’re right Mike- as I woke up this morning I realized what I had written yesterday 🙁 I hope no one takes that advice, sorry.
FPL ‘One Plug Device’ will permit any generator up to 7000 watts including an RV as input source. Just don’t flip on (breakers for) big loads like A/C or Heat or 240 appliances.
I’ve looked into this previously, and it’s not code compliant in many states. And since your RV’s onboard generator doesn’t output split-phase power it’s possible to over-current your shore power cord’s neutral conductor and burn it up.
We did not consider a generator for our home until the October Ice Storm in 2006. We had just returned from a 2 month trip in the North East Maritime States, and had not been home a week when the ice storm hit. With the leaves still on the trees, the ice build up brought large branches down onto power lines. The power pole in our back yard broke in half and the transformer buried itself into the ground. Because our power poles were in our back yards and not accessible from the street, we were without commercial power for 18 days before commercial power was restored. We used our Motor Home Generator to power the fridge, freezer, furnace, TV’s and some lights in the house. Because we are on the road over 5 months a year we purchased a 10 KW full house generator and do not worry any more about power outages back home. Stay safe, Stay well, Safe travels.
Sorry, Mike, but you struck out on the statement that the power will only flow in one direction through the cord connection. Electricity doesn’t care what direction it travels in. If the house power is out and there isn’t a transfer switch blocking the flow, why wouldn’t the generator power back feed into the house? It will. Maybe you misspoke but your statement is wrong. Electricity WILL flow backwards through a cord connection if the normal supply is off.
VERY dangerous situation, but yes, if wired that way it would flow back into the shore cable…
Perhaps I should have said “Should Not Flow from the RV to your House.” I’m assuming that your RV generator has been properly wired with some kind of transfer switch. If it was a DIY install (not to code) without a transfer switch (either manual or automatic) then it’s possible for current from the RV generator to flow back into your house wiring. But that’s a huge code violation and extremely dangerous.
You tend to forget about those of us with entry-level coaches and Class-C’s.
Remember, we have to plug our shorepower cable into a 30A 120VAC receptacle in one of the bays – usually the power bay.
With a double-male cord, you can open your mains and feed one “leg” of your main panel. If you get even more creative, then a double-male heavy-duty extension cord can be used to jumper two outlets and power the other “leg”.
NOTE – in this configuration all 240VAC load breakers should be opened – you *will not* have 240VAC. This will only allow all lights in the house, and connected equipment to be powered. A ceiling fan and light in each room goes a long way to keeping momma happy.
NEVER use a male-to-male “suicide cord” to plug any generator into your home electrical system. Not done correctly that can get someone killed. If you do want to power your home from a 30-amp/120-volt onboard you still need to install some sort of home transfer switch that allows you to select which home appliances get generator power. More to write about….
I just open the main breakers that feed the house and plug my generator into a 220V 30A socket. When power is restored I just unplug the generator and turn the main breakers back on.
Whenever we lose power at our house, I simply start up the diesel generator and run a 12 gauge extension cord into the house to keep the refrigerator running and some lights and fans if needed. Can’t run the AC but if I get too hot I can sit inside the coach where it would be nice and cool. Actually, we could easily live in the coach and just keep the electric going to the frig so the food doesn’t spoil.
Can always run a power cord into the house directly to your most important appliance, the frig. After every hurricane, there are tons of items requiring a frig that are ruined and tossed into the waste stream.
I did the same thing when a tornado knocked out power for two days. Helped out the neighbors, too, so their food didn’t spoil. BBQ grill convenient for cooking along with the RV stove.