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Use Motorhome Generator as Back-Up for Sticks & Bricks Home

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This is probably an "out in left field" question for the forum but I'll ask it anyway (and no I haven't been consuming adult beverages!).    The Houston area has experienced more frequent power outages the last four months first with the Great Freeze in February followed by severe thunderstorms the last couple of weeks.  The power outages have lasted 2-3 days (Great Freeze) and lasted 24 - 36 hours with recent severe thunderstorms.   Hurricane season begins in a week which could bring more power outages.

I've priced Cummins and Generac permanently installed stand-by generators and was shocked to learn the "turn key" price is ~$12,000.   A large portable generator (such as a Winco 12,000 watt generator) costs ~$4,500 plus the cost to install a manual transfer switch.    Like many of you, I already own a nice generator in the form of a Onan QD 8000 watt tucked away in the front of my coach.  In my simple Chemical Engineer mind (I am very far from being an electrical engineer / electrician) a "switch" with receptacle et conceivably be installed in my "electrical bay" to use the QD8000 to partially power my home during a power outage (i.e. the switch would disconnect the coach from the generator and direct generator output to the home).    Is this thought feasible?    Has anyone used their coach's generator to power their home?

For reference this article shows how a portable generator (for me the Onan generator in the motorhome) to a house electrical panel -->  How To Connect Portable Generator To Electrical Panel 2021 (gelawncare.com)

Yes I know I could run several extension cords from the coach to provide power to the refrigerator, freezer, television and oscillating fans.  Connecting the coach's generator directly to the house electrical panel would mean have power to operate the 3.5 ton A/C unit or furnace.     The forum's thoughts please.   It's OK to say if my question is "crazy".  

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Not crazy at all. It seem possible that a plug installed on the coach and into your power panel would work. I would run at least #8 to the panel. Be sure the area where the generator is running well ventilated.

Herman  

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Like the illustration you linked to shows'. You absolutely need to isolate the house from the power grid. You also need to use the existing fuses to protect your circuits. Feeding power directly to some appliances and eliminating the circuit breakers could be a problem.

I will say it again. You absolutely need to isolate the house from the power grid. The problem is when power is feed the wrong way during a outage the the low voltage is stepped up when it goes through the transformer that 10 volts may come out 100++ volts. As you can imagen this is dangerous to people trying to work on the system and restore power. 

Bill

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We have a manual transfer switch wired into the house. You could install an outlet in the coach at the transfer switch and run a heavy cord between the two. We do that now but with a stand-alone generator 

https://www.amazon.com/EGS107501G2KIT-10-7501G2-Detailed-Instructions-Flexible/dp/B005FQJD7K/ref=asc_df_B005FQJD7K/?tag=hyprod-20&linkCode=df0&hvadid=167151917227&hvpos=&hvnetw=g&hvrand=16496119270690528530&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9007361&hvtargid=pla-308399583010&psc=1

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You have a great idea, although the QD8000 will not run that 3.5 ton house AC. It will  run many of your 120 volt appliances, but those 240 volt ones will not run on a 120 volt generator. Best advice is to move into the MH when those blackouts occur.

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I don't get the $12,000?

We got a 22 Kw, LG, Generac for Ranch and a 17 Kw, LG for Camp house, fully installed for $13,500.  The Polar Vortex made a believer of my DW!  We chose LP because off 2 reasons...at the camp house we have a 250 gal tank, at the Ranch we have a 250 gal and a 500 gal tank!

In the event of a black out, no elect. it takes elect to get gas or diesel.  :(

At my friends Ranch in Gladewater, TX., I did supplement the power, with my coach generator, 10 Kw!  Fridge, lights, TV. for 6 hours.

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We just had power grid upgrades and power off Saturday 9am to 5pm

then Sunday 9am to 3pm

I turned all my breakers off including main 

ran patch cord to the range plug I have in the garage 

tied both legs together and only turned on what I needed paying attention to the fact I am using a 10gauge cord 

so fridge freezer and coffee 

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A tap can be installed on your power panel after your main breaker. The tap can be connected to your RV via a heavy cord Min. 8 gauge preferable 6 gauge.

Before making the connection be sure to turn off the main breaker!   

Herman

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But if I remember correctly, doing this does not meet the National Electrical Code where automatic transfer is needed. 

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  You can buy kits for a manual disconnect that will install in your house breaker panel and will lock out generator power from utility power. I would get an electrician to do the work if you are not skilled to do the work safely. Typically with a portable generator this work is routinely done. He will install a new 240 volt breaker and wire in a 50 amp outlet on the house. Then you would need a 50 amp cord to the RV but again you would have to install a 50 amp outlet on the RV from the generator. 
  A Safety disconnect is a must!

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Either an ATS or a manual TS is required by almost all utility power companies, including REMC's. It must be configured for an either or position,  the transfer switch will either be in the public utility position OR the on-site generator position to supply power to the building.

When you simply turn off the main breaker in the entrance panel you have not disconnected the neutral connection to the public utility wiring.

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The ground and the neutral are connected to the body of the breaker panel  so joined so the neutral is not completely disconnected with an ATS 

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Carl --

If I understand your response the cost for your two stand-by generators was $13,500?     The current "all-in" cost in the Houston area for a 20,000 watt stand-by generator is ~$13,000 whether from Generac, Kohler or Cummins dealers.  And the wait time is at least 3-4 months due to back-log for a generator due to the lack of semi-conductors / circuit boards that is affecting many manufacturing businesses.   The cost of the generator plus auto transfer switch is ~$6,000.   I'm struggling to understand why the installation cost is $7,000 for two journeymen for 6-8 hours of work. 

Rather than spend that many $ on a stand-by generator that may not get used often, my next thought is to spend $ modifying my drive-way to handle the turning radius of my coach and have a gentler slope so the back of the coach won't drag on the street.   I'll start a different discussion about how to modify a driveway to accommodate a 41 foot coach.  

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To do the job with auto change over  

needs all above plus a second breaker panel to feed the circuits that are to be fed by the generator  with 100 amp two pole breaker in main panel to feed transfer switch 

and new panel  as most of your home needs to be isolated from generator 

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I need to understand a bit about A/C current. 

If you connect your generator to your main panel below the main breaker (both legs the neutral and the ground) and apply power from the generator will you have power feeding back through the neutral making it hot? I understand that the main MUST be turned off.

Herman

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5 hours ago, hermanmullins said:

I need to understand a bit about A/C current.

In American standard wiring, single phase circuitry, 240 volts AC is generally used, it requires two hots to be 240 volts, neutral is the common to ground necessary to be able to use 120 volts only. So if you are using 240 volts to a 240 volt appliance only, a safety ground is all that is needed. An electric range in most cases uses 240 volts only for the oven element only, the stove top eyes are generally 120 volts, as well as lights and control devices, therefore by todays code require two hots, one neutral, and one frame/safety ground, four wires. Neutral and safety ground are only bonded at the point of entry of the main breaker panel. In your motorhome that same bonding only occurs at the CG point of entry main disconnect. The neutral carries the same amount of amperage from the appliance to earth ground if the same amount of current is not being from both L1 and L2 of the 240 volt circuit, ie. if one leg has 20 amps being pulled and the other leg has 10 amps being pulled at the same time, then 10 amps unused is being transferred through neutral to ground, so yes neutral can be and usually always can be lethal. This is why safety ground is always isolated from neutral all the way back to the point of entry. Electricity will always take the shortest route to ground. When a generator becomes the source of power then the neutral circuit of the generator takes that unused amperage back to its own circuitry. Frame/safety ground on the generator is handled just like a standard house circuit, neutral is not bonded to frame on a generator either, that is why the generator is mounted to the frame through rubber, for isolation. The NEC does require a transfer switch to be used instead of wiring directly below the main breaker, although in my state the transfer switch can be manual or automatic, but it is required, if one gets caught negating this code, a fine can be levied if the the electric company or inspector finds out about the breach. Remember that just in case of an accidental turn on of that main goes directly to the grid, and the 120 or 240 volts is in turn transformed back to the original source through the same transformers that transformed from 4000 or 10,000 volts, this could be lethal to a lineman working to restore power back to you. Or if the generator is on and that main happens to have moved to on during the outage and power comes back on, it will make a mess of your wiring and your generator. I know this is lengthy, but hopefully is understandable enough that novices will not try to break the rules for obvious reasons.🥶

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"The NEC does require a transfer switch to be used instead of wiring directly below the main breaker, although in my state the transfer switch can be manual or automatic, but it is required, if one gets caught negating this code, a fine can be levied if the the electric company or inspector finds out about the breach. Remember that just in case of an accidental turn on of that main goes directly to the grid, and the 120 or 240 volts is in turn transformed back to the original source through the same transformers that transformed from 4000 or 10,000 volts, this could be lethal to a lineman working to restore power back to you"

Kaysmith that happened about 35-40 years ago in Indiana. An ice storm tore down many miles of lines, a farmer had a large genset to handle and cool his dairy farm. He simply disconnected the main breaker, started his genset and blissfully continued his operation. When a lineman discovered live wires from back-feeding he shorted them with a chain. Naturally this ruined the farmers genset and he complained to the utility company. The utility company took legal action, resulting in the farmer losing his farm and entire dairy operation.

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I didn't know about this accident, but know of many more. Sad, but accidents do happen, only takes one mistake and many can suffer from it.

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The house end of a temporary generator connection:  Living on the Gulf Coast, extended power outages are not uncommon.  We've had a portable generator since Hurricane Ivan in 2004.  Although it is technically illegal, I pull the meter and  connect the two 120V leads from the 240-volt generator tap to the bottom two brass tines behind the meter and the neutral to the ground cable (the bare stranded aluminum one), thus guaranteeing that I don't feed power back into the utility's lines and fry a lineman.  For this I cut the female receptacle off a marine shore power cable, separated the three wires, and attached the jumper cable-type clamps to the hots and the neutral.  I also run a bare copper ground from the frame of the generator to the house's ground wire.  When the power comes back on I notify the utility that I have pulled the meter and then reinstalled it, and request that they install a new seal.  So far they've been grateful.  

The coach end of a coach generator-house connection:  I can't get my coach anywhere near our meter panel, have not considered doing this with the coach generator, and therefore can't add to the discussion about how to tap into the coach generator's output and run power to the house panel.  

Edited by urbanhermit

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I'm  sorry but can not condone one bit of what you just said. And besides it is Illegal in so many ways, Might I suggest that since you live in an outage prone area that you invest in a standby generator wired in through a proper transfer switch by a licensed electrician. Be safe for yourself and all of the emergency worker that are there to help.

Now off my soap box.

Herman  

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10 hours ago, urbanhermit said:

Although it is technically illegal, I pull the meter and  connect the two 120V leads from the 240-volt generator tap to the bottom two brass tines behind the meter and the neutral to the ground cable (the bare stranded aluminum one), thus guaranteeing that I don't feed power back into the utility's lines and fry a lineman.  For this I cut the female receptacle off a marine shore power cable, separated the three wires, and attached the jumper cable-type clamps to the hots and the neutral.  I also run a bare copper ground from the frame of the generator to the house's ground wire.  When the power comes back on I notify the utility that I have pulled the meter and then reinstalled it, and request that they install a new seal.  So far they've been grateful.  

Yes this is technically illegal, but it is the safest method in the absence of a good reliable transfer switch. As us licensed amateur radio operators learned while studying to get our license, in a true emergency, anything goes. But, if I lived in an area where there were potential long term outages, I would install a useful manual transfer switch and a circuit breaker box for 100 amps, then wire the portable hookup properly. I can do the work myself so the potential cost is about $300.00. If one cant do their own wiring, a competent electrician can be hired for about another $500.00 in this area under normal conditions.

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19 hours ago, hermanmullins said:

I'm  sorry but can not condone one bit of what you just said. And besides it is Illegal in so many ways, Might I suggest that since you live in an outage prone area that you invest in a standby generator wired in through a proper transfer switch by a licensed electrician. Be safe for yourself and all of the emergency worker that are there to help.

Now off my soap box.

Herman  

Condone it or not, I've been doing it for 20 years; it's 100% safe; and the power company hasn't complained once. 

Edited by urbanhermit

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On 6/15/2021 at 11:25 AM, urbanhermit said:

Condone it or not, I've been doing it for 20 years; it's 100% safe; and the power company hasn't complained once. 

Generac makes an automatic transfer switch for exactly this application: GenerLink MA23-N - City Plumbing & Electric (cpesupply.com)

 To everyone else:

There is no excuse for not having a transfer switch, here's one for only $63: PowerMax PMTS-30 Automatic Transfer Switch | Northern Arizona Wind & Sun (solar-electric.com)

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8 hours ago, wildebill308 said:

I can't get my RV close enough to do it

If you have wired a 50 amp service for your MH, to your home breaker panel, you can backfeed through this service, with a little ingenuity.

Edited by kaypsmith

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