House power from RV generator as back-up

No!  No!  wiring the onan output to both "hot" terminals will NOT be a good thing!   The two lines will be in-phase, not 180 degrees out of phase.  So all your 220 "appliances" will be fed 110 (120) and will blow the system!

Volkemon is absolutely correct, all the 220v breakers must be Off!

The main breakers from utility power must also be OFF.

Unless you can feed 2 out of phase lines to your distribution panel (and that is not possible from the RV generator) you must have those 220v breakers off!   Before you plug in the generator to the distribution panel.

Then, and only then will it be safe and supply all other breakers with appropriate power.

The generator must be disconnected before any breakers are reset, distribution panel first, then main breakers last.

Mike,

You are correct in that it would be ideal if I had a 240V 6K generator, but that deceives the purpose utilizing the PC's 4K generator with a supporting 40 gallon mobile fuel tank.

This may sound even more "Out There", but given my situation, I wonder if making a special cable to provide 120V power to both hot terminals on the 240V garage receptacle, would distribute adequate power through my entire breaker panel, both sides of it.

Mike, Jatrax, Volkemon......
I know, I know, I know....about making sure the main 200amp breaker if "OFF" before doing anything else.  I am trying to utilize everything I already have on-hand for a "once-in-15-years" situation.

Ron, I understand the "once-in-15 years" criteria.  You've made your point about careful and judicious use of your resources several times before on this forum--nothing wrong with that.  Also, various risks are not the same everywhere.  It may be that your environment has a relatively stable electrical grid.  Sure outages can occur anywhere, but you're not on a rural cooperative in Oklahoma with miles and miles of rural open lines that are annually subject to lightning strikes, tornadoes, and ice storms or snow overloads that can knock power out fairly routinely.  What makes perfect sense for me might very well be overkill for you.

In any case, you are thinking "outside the box" with your idea of modifying a cable to power both hot terminals of your 240 volt wall receptacle with a single 120 volt source.  I see no reason why it wouldn't work with one critical requirement.  All of your 240 volt breakers would have to be switched OFF, and remain OFF (except for the one feeding your garage receptacle, of course).  In addition, please confirm that nothing else except that receptacle is fed from that breaker (there should be nothing else--but you never know).  The two "hot phases" of the panel are segregated from each other (although they share the common neutral), so for the 120 volt circuits, energizing each one should be like powering each side individually.  But every 240 volt breaker combines both of those phases into one feed to whatever uses it, and you can't have that common 120 volts on each side of the 240 volt circuit without potential problems.  So, in addition to having the main breaker OFF, you would absolutely have to maintain all of your 240 volt breakers OFF as well (except for the one feeding your garage receptacle).  Of course you'll still be limited to 30 amps total of 120 volt power, but it should be available on all of your 120 volt circuits.  It would be up to you to carefully manage the total load.

I'm going to repeat my disclaimer that I'm not an electrician, and while my earlier comments detailed things I've personally done and that I know work, I've never tried this particular avenue.  In theory I see no reason why it won't function as described.

Mike

I wonder if making a special cable to provide 120V power to both hot terminals on the 240V garage receptacle, would distribute adequate power through my entire breaker panel, both sides of it.

Ron, technically what you are describing could be done.  But I have to emphasize it would be against code and potentially dangerous.  AND, it is not going to power everything in your panel, that load is 200 amps and the generator is providing 20 or maybe 30.  Please do not do this.

It would be far cheaper and much less dangerous to simply run extension cords from the generator to the appliances that must be kept going in a once in 15 year event.  Redo your furnace connection as described earlier and run cords to the furnace, refrigerator and freezer.  Run another to the kitchen and you might be able to run the microwave as well.  You can hook all of that up to the external plug on your PC and be safe and within code.

I Love you guys!

I greatly appreciate everything shared by all here.  What fears me the most is on a very cold night in January, the power will go out and we are watching the temperature drop inside the house and out of desperation, I do something stupid.  Jatrax makes an excellent point, just do it the "safe" way and run a standard 120V extension cord from our PC to the furnace system in our house.  I would need to setup something in advance at the furnace to accept an external 120V input for that "just-in-case" scenario.

As far my house power panel is concerned, this is it.  The top main breaker has "200" molded into the handle.


The 240V-50 amp breaker pictured here in the garage, is the one unlabeled in position 30/32.


From what you are saying, if I try the back-voltage approach at the garage utilizing a single hot wire (not both on the 240V receptacle) only the breakers on the right side will function.  If this is true, than the process would be as follows.  BUT prior to all this, my PC needs to have a 30A output off the power transfer switch (per Volkemon), and also on hand, a specially made 30A male/male power cord.

0) Back the PC out of the garage per 2 Lucky below. 
1) Start the PC generator allowing it to warm up to operating temperature, and turn off all 120V breakers in the PC.
2) At the house breaker panel, turn off every breaker including the main 200A
3) Plug the 30A male/male power cord "FIRST" into the garage 240/50A receptacle through a standard 120V-30A/240V-50A adapter.
4) Plug the male/male power cord "SECOND" into the PC 30A Power-Out located by the power transfer switch.
5) At the house breaker panel, turn on only the 50A breaker that supports the garage.
6) See what happens, listen for voltage humming, electronic smell, etc.
7) Turn on the furnace breaker and see if the furnace kicks on....hopefully it does.
8) Once the house is warmed up and the furnace shuts down, turn off the furnace breaker and turn on the breaker that supports the fridge.  If not working (on wrong side of panel #19) power an outlet near by and use power cord to power fridge as needed.
9) In between, and maybe along with keeping the house warm and the fridge cool, maybe we could run some creature comforts through powering up a second breaker.  The PC generator will let me know if it's too much to handle.

Under NO circumstances, should a different 240V breaker be flipped on.  We are on a private well that utilizes 240V.  We would have to live without running water.

#1 should be move the PC out of the garage so you don't asphyxiate on CO from the generator.

#1 should be move the PC out of the garage so you don't asphyxiate on CO from the generator.

Of Coarse! 
I added step "0"

Ron,

One important correction to your understanding.  DonC13 and I identified it in a couple of postings on page 2 of this topic, and I guess you missed the correction.

If you use your planned connection of applying 120 volts through the 30 amp adapter to only one phase of your main panel--it is true that only 1/2 of your 120 volt breakers will be energized.  I had originally stated that that would be either the left side or the right side of your main panel breakers.

However, Don reminded me that the internal connectors for the breakers alternate to the left and right sides as you go down the panel.  That means that if you energize only one of the two hot connections, instead of ALL the breakers on the left side OR ALL the breakers on the right side being powered with NONE on the opposite side--------in reality the powered breakers will alternate left and right as you come down the panel.  A 120 volt breaker on the left will be energized, then--next down--a 120 volt breaker on the right will be energized.  The alternate breakers on each side will still be dead.  So instead of all your hot breakers being on one side--in reality they will alternate side to side as you come down the panel.

Now, I can't tell you which of the two hot connections in your receptacle connect to which phase/side of the main panel----what I can tell you is that switching to the opposite hot lead will switch the breakers being energized.  That means that one hot connection in the plug that goes into the wall receptacle will energize one alternating set of breakers, and changing the hot connection to the other plug lead will energize the opposite alternating set.

Hopefully this is clear as mud, but it's an important change to your understanding of what to expect.  Other than that, your listed sequence appears correct.

Mike

Mike, I missed that point earlier, and "I Get It" now.  That actually makes a lot more sense.  I was scratching my head in how 240V worked with my previous understanding.

Going full circle here......
Given my particular situation, If I energized both hot leads in the 240V receptacle in the garage, that would make my entire panel straight 120V, right?  As long as all my "other" 240V breakers remain "off", it seems I would do no harm.  This way I can selectively turn on the 120V furnace breaker, 120V fridge breaker, and maybe another 120V creature comfort breaker anywhere inside the panel.  I would be limited only to what the PC Onan 4000 can output.  If I over-load the generator, it would simply trip it's safety mechanism as it has been known to do when running the PC a/c unit, microwave oven, and coffee maker in unison.

Right?

Ron...

https://forum.phoenixusarv.com/index.php?topic=4297.msg37657#msg37657

Ron...

https://forum.phoenixusarv.com/index.php?topic=4297.msg37657#msg37657

I get it!

Ron,
There are so many things wrong with your plan I'm not even going to list them.

All I will say is that technically what you are planning might work.  And if only one tiny thing out of a whole list goes wrong you end up with a range of bad results.  Ranging from a blown breaker to starting a fire.

If it was a true emergency and you had no other options or choices yeah, I might try that.  But there is a much simpler, safer and to code way of doing it.

it seems I would do no harm.

This phrase just plain sends chills up my spine. 

Ron,
There are so many things wrong with your plan I'm not even going to list them.

All I will say is that technically what you are planning might work.  And if only one tiny thing out of a whole list goes wrong you end up with a range of bad results.  Ranging from a blown breaker to starting a fire.

If it was a true emergency and you had no other options or choices yeah, I might try that.  But there is a much simpler, safer and to code way of doing it.

Quote

it seems I would do no harm.

This phrase just plain sends chills up my spine.

I hope never to have to rely on our generator.  That being said, I also hope I never regret not taking your advice.

Mike, I missed that point earlier, and "I Get It" now.  That actually makes a lot more sense.  I was scratching my head in how 240V worked with my previous understanding.

Going full circle here......
Given my particular situation, If I energized both hot leads in the 240V receptacle in the garage, that would make my entire panel straight 120V, right?  As long as all my "other" 240V breakers remain "off", it seems I would do no harm.  This way I can selectively turn on the 120V furnace breaker, 120V fridge breaker, and maybe another 120V creature comfort breaker anywhere inside the panel.  I would be limited only to what the PC Onan 4000 can output.  If I over-load the generator, it would simply trip it's safety mechanism as it has been known to do when running the PC a/c unit, microwave oven, and coffee maker in unison.

Right?

Ron, sorry for a late response--had to run to Tulsa today so was away from the computer until this evening.

There are a lot of posted questions that I don't try to address on the forum, but when I do address one (such as 2 Lucky's original post), I feel an obligation to stay in the conversation to the extent I can contribute as long as any questions keep coming.  I also feel obligated to try to answer technical issues accurately and straightforward--with my very best knowledge and understanding.

It is obvious that both DonC13 and JATRAX have very strong advice that this particular modification and approach should be avoided.  I have read many, many of their posts over the years and respect both of them greatly.  I have already said, but will say again, that they are absolutely correct that the whole back-feed approach is not code compliant, and any non-code modifications are inherently risky, because the whole purpose of the NFPA 70 National Electrical Code is to eliminate danger and risk from electrical work.  So my response is not to argue or debate the advice they have given, but simply to answer the question you asked as accurately as I can based on how electricity works.

If you energize both hot leads in the 240 volt receptacle in your garage, the 120 volt potential will back-feed from your receptacle on BOTH hot wires that connect through your 50-amp breaker to EACH side of the main panel in your wall.  The two separate "hot" copper or aluminum busses in your main panel--that normally each carry 120 volts out of phase with each other--will now each be energized with the same single phase of 120 volt electricity that your generator is providing.  Since those two busses in your panel are necessarily isolated and insulated from each other, they essentially then function like two independent busses receiving the same input.  Electrically, this condition in itself does not present a problem.

The potential problems ensue with the external connections into or out of the main panel.  You already understand that if the panel 200 amp mains are not disconnected, the panel can then back-feed and electrify the lines coming into your home; in addition, if external power is suddenly restored, you then have two separate sources of electricity feeding your panel----it is critical that both circumstances be avoided by always keeping the mains open.
The other issue is with all of the breaker-fed circuits to various places in your home.  Since every 120 volt breaker accesses only one side of the panel, both busses being energized do not affect that 120 volt circuit.  It simply picks up the 120 volts from it's respective bus just the same as it would if a proper 240 volt source was feeding the panel.  In the case of the proper 240 volt source, roughly half the 120 volt breakers would be on a different phase than the other half, but they don't know that--they just see 120 volts.
The potential problem is with the 240 volt breakers (except for your receptacle breaker through which you're back-feeding).  The other 240 volt breakers are now energized from both busses---just like they would be from a 240 volt source, EXCEPT those two busses are NOT at different phases, and they do NOT now equal 240 volts across the two hot wires coming out of your 240 breakers to your appliances.  That, again, is a critical condition that you absolutely cannot allow to exist.  That is why it would be just as crucial (in the case of this type hook-up) that ALL of your 240 volt breakers be kept OFF.  As long as the breaker is OFF, the fact that the input to the breaker is incorrect shouldn't be an issue---the two individual circuits through each 240 volt breaker are necessarily isolated and insulated from each other, just like the busses are.  If the breaker is switched OFF, there is nowhere for the improper 120 volt potential to go; it simply sits there on the input terminal of the breaker.
There is really no difference here from your necessary action if you were only energizing one side of your wall receptacle with your generator-----since each 240 volt breaker would have power on one lead and not the other, you would still want to keep all of your 240 volt breakers switched OFF, to prevent only 120 volt power from being provided on a single leg of the feed to your 240 volt appliance.

As a last comment I will repeat what I previously said about this:  I've never had occasion to personally use this particular approach----but I see no reason why it won't function as described.  That is not a recommendation, it's just the technical answer.

Mike

 

That being said, I also hope I never regret not taking your advice.

Ron, if I didn't have a lot of respect for you and your contributions here I would have shut up a long time ago.  I'm starting to feel like the guy standing aside and watching as the train wreck occurs.

My house in Oregon was in the national forest at the end of the road as far as power is concerned.  We lost power for significant amounts of time (greater than 4 hours) at least once a month and sometimes once a week in the winter.  So I have lots and lots of experience with running a house on a generator.  There are safer ways to do what you want to do.

Anyway, best of luck and I sincerely hope nothing bad happens.

This has been an interesting thread with lots of good info.
But I have to side with jatrax on this one.
One thing that has not been discussed is the common use of multiwire branch circuits in residential wiring.
Not every electrician uses them but most do.
What they are: instead of using say two 14/2 Romex cables to a remote spot in the house for two circuits, they run one 14/3 cable.
They are also widely used in service relocations where you need to get a lot of circuits from point A to point B.
The two hots share one neutral and because they are out of phase the neutral currents cancel each other out.
This saves money on copper and is safe. (until you have a broken neutral)
In the good old days these were wired to regular single pole breakers located next to each other in the panel to get the 240V between hot legs.
More recently the code requires them to be installed onto a double pole breaker.
In your scenario of feeding the entire panel on  one 120V 30A generator, both of the hots in the multiwire branch circuits will be in phase with each other.
In this instance the neutral currents ADD. So it would be possible to have up to 30 amps on a neutral wire designed to carry 15 amps. Not safe.

Another thing to consider is even if you only power one side of your garage plug with 120V, you would STILL need to turn off your double pole 240V breakers.
Reason being, if left on you could get a back feed through a 240 volt appliance say a stove or electric water heater element for example, that would effectively put the circuits that you did not intend to feed with 120 V in series with the 240V elements of your appliances. This would provide a lower voltage to your 120V items that your electronics will not like.

One other point to think about is if you were to do something like this, and god forbid something happened to your home (or you) and authorities or even worse you insurance company found a non conforming condition, you could risk losing coverage for damages.

I see you already know the importance of plugging in the garage outlet BEFORE plugging into the generator, but hey we are all getting older and sometimes we forget and having those blades of the male cord end energized and exposed can be a real threat to your health. (and just one more code violation)

WIll it work, yes if you get it right, but there are so many violations that I don't think it is worth the risk.
So like I said, I'm with jatrax on this, if it is not worth the expense of doing a properly wired transfer switch to you then please just run an extension cord to the generator and plug in the appliances you need.

Just my 2 cents.