House power from RV generator as back-up

Volkeman, yes there is some power needed for the boiler. The gas valve is about .5 amp, not sure what the piezo igniter uses to light it, and the flue vent damper takes another .6 amps, all in all not a lot of juice. Interesting to think I can run it off of my PC solar system and inverter!

My fireplace has a pilot  light, so no power needed there.

Adding a plug in line as Mike said is a good idea also, and does make sure you cannot backfeed through the supply.      I was aiming for a little more inspector-friendly setup.

**********************************************

Curious... I never did any NG burner work, they did not have NG service in our area.  The boiler/heat exchanger uses no or negligible power?  Even in forced air apps?  Being used to oil fired, there was ALWAYS current draw just to make the heat.

The 5 ton AC in our house has a blower rated 3/4 HP or 4.6 amps @ 220V.  So the blower alone is close to 1000w at full draw.   480 watts for a whole house heating system is FANTASTIC.       I cant even blow the air around our house for twice that power, much less run the heat pump or heat strips.

Volk,

That's why, in areas where it's available, natural gas is heating is typically significantly cheaper than electric.  Certainly here in Oklahoma, and even at the higher prices for NG of today.  In small systems (hot water heaters, 30K BTU open flame free-standing heaters, even the 50K BTU dual wall furnace in my grandson's house), there is no electricity used at all.  Heat flow is by convection, and in standing pilot systems, a 750 millivolt thermopile heated by the pilot provides all the energy needed to hold in the pilot safety valve and activate the solenoid in the main gas valve as called for by the thermostat.  In larger, more sophisticated units, such as my central furnace and 2 Lucky's unit, 120 volts supplies the control systems with the gas valve/thermostat circuit powered by 24 volt transformers, but power draw is still almost negligible.  In his case there is no blower, but there are circulating pumps; my unit being forced air and 5 ton A/C uses the same 3/4 HP squirrel cage setup as yours.

Mike

.... you will only energize the one side of your main panel that carries the circuit breaker for your garage circuit.  Other breakers on that side of the panel will have power, but none of the breakers on the other side of the panel will have it. ..


Mike

Mike,

One correction.... Not ONE side or other of the breaker box but every other breaker on either side.  Each side carries both phases.

That way to get 220v for say an A/C, electric range, dryer, etc. you stack 2 breakers latched at the toggle switch on the same side of the box.

Or at least, every residential breaker box I have worked on (maybe 8 to 10
distribution boxes) was set up that way.

Don

You're exactly right Don--thinking about the two phases tying in to each side, but the connector busses do alternate side to side as they go down the panel.  As you say, that is the way a dual breaker (240 volt unit) accesses both phases.

So to correct the comment to Ron, if you hook in a 120 volt back-feed to the panel, it is true that only one-half of your 120 volt breakers will be energized--but instead of them being only on one side of the panel it will be alternating breakers, top to bottom, on each side.

Thanks for the clarification, Don.  Every box I've worked on is set up that way also.  Getting old...........
 

Quote from: Ron Dittmer on December 14, 2020, 11:14:20 am

This is a very interesting subject.

I have wondered if there was an easy way to jury-rig something.  In my head, I have wondered if this would "safely" work.

1) Flip "OFF" the main house breaker(s) to isolate the house from community power.
2) Turn off every small breaker that distributes power throughout the house.
3) Plug the PC generator into my 30amp outlet in the garage, but I wonder how to output 110V-30amps direct from the PC generator.
4) Turn on only one house-distribution breaker at any given time.
- Run our gas fired forced-air furnace until the house warms up.  The 110V power required would be only for the furnace blower.
- Flip breakers to run the kitchen fridge until it shuts off.
- Flip breakers for other purposes as needed.

Being on a private well that requires 220V, that seems to be a "bust" just like a/c, but everything else just might work.  Having our house 100% converted to LED light bulbs throughout should also make a difference.  Where we live near Chicago, the focus is more on keeping the house warm in the winter rather than cool in the summer.

Does anyone know how to output 110V-30amp from their PC generator?

Ron,

The short answer to your basic question of "can this safely work" is yes.  But it must be done with caution and complete understanding to meet the "safely" criteria.  To begin with--it is truly "jury-rigging" as you say; and it is certainly not to code.  And any electrical modifications that fall into the category of "jury-rigging" are inherently unsafe and dangerous unless you absolutely know what you are doing.  Supplying auxiliary power to your home should absolutely be done through a transfer switch which, if properly installed, will protect your home, your auxiliary power source, and the community power line feeding your home.  However I do provide emergency power to my home safely from an auxiliary generator through a back-feed type connection, which is essentially what you describe.  In my case, it is a full 240 volts, and I energize my entire main panel.  My generator is only about a 6KW unit, so it can't carry my central air conditioning, and I do monitor loads, but everything else is operable.

Your last question of how to output the PC generator is answered in my and especially Volkeman's comments above.  You would need to tie in to the transfer switch on your PC to access the full generator output, and wire in a receptacle that will let you connect a 120 volt, 30 amp cord set to your garage outlet.  With your house main breakers switched "OFF" to isolate you from community power (absolutely critical, and the first thing to do), you would then back-feed to your main panel through the circuit breaker that feeds your garage 30 amp circuit (that breaker must be "ON").  One limitation that you may not have considered is that since you are only feeding in 120 volts, you will only energize the one side of your main panel that carries the circuit breaker for your garage circuit.  Other breakers on that side of the panel will have power, but none of the breakers on the other side of the panel will have it.  It will come down to "luck of the draw" as to which other house circuits are on that panel side.  That's the advantage of a 240 volt capable auxiliary generator--in that case, with the same back-feed process, you feed the main panel through a 240 volt breaker, which energizes both sides of the panel.  In my case, I installed a 240 volt 60 amp sub-panel in my garage for outside power and lights, and that's where I tie in the generator.  With the main breakers to my main panel switched OFF, and the 60 amp breaker to my sub-panel switched ON, my main panel has 240 volts back-fed from the sub-panel to all circuits.  My generator breaker protects that feed, but in practice, I still keep my high amperage 240 volt breakers (A/C unit, electric dryer, etc) switched OFF to prevent accidental overloads.  Even the small 6KW generator carries everything else easily (including my NG central heat blowers), so can remain pretty normal during outages.  Last usage was only about a week ago, when we had a 24-hour outage on our rural electric cooperative system, and it was nice to have normal heat and power.  In 2002 we had a severe ice storm and our outage stretched to 13 days in our rural area, that's when I first acquired the generator and established the hook-up.

Mike

I found Volkemon's Transfer switch receptacle post.  I will look into that.  I thank both of you.

About my particular situation.  I have a wall outlet like this right by the RV over-head garage door.  Now I am thinking I have a 240V receptacle there.


Typically when I plug my PC into it, I use an adaptor similar to this.


If I back-feed 120V-30A from the Onan 4000 into that outlet through such an adaptor, I think I am supplying power to only one of the two hot wires back to the house.  Oh well.

Project #1 is to get a 120V-30A receptacle wired off the power transfer switch inside our PC.

It is too bad Onan did not include direct power outlets on the generator like a normal generator has.

In the new house I insisted they install a "priority circuit panel".  This is a sub panel of the main that has in it all of the circuits that would be run by a generator.  Lighting (all LED), freezer, refrigerator and a few plugs here and there.

The panel has a transfer switch so it is either fed from the main panel or a generator input receptacle located outside.  The plan is to run that panel from the generator in the cruiser or from a separate generator that can left to run outside and plugged into the outside receptacle.  Everything wired to code, inspected and approved.

The problem with using the PC generator is it is 120 only so it will power only one side of the priority circuit panel where a real backup generator would power both.  Still it will work and that is what I have in place for now.  I may eventually buy a separate generator but its OK for now.

Quote from: Ron Dittmer on December 14, 2020, 11:14:20 am

1) Flip "OFF" the main house breaker(s) to isolate the house from community power.

""Turn off every small breaker that distributes power throughout the house."" 
TURN OFF THE BIG ONES TOO!!! THEY WILL BACKFEED ONE LEG!!!

Did I not cover that one?  Or am I missing something I need to think about?

If I back-feed 120V-30A from the Onan 4000 into that outlet through such an adapter, I think I am supplying power to only one of the two hot wires back to the house.  Oh well.

Ron, back feeding into a house receptacle like that is against code and potentially dangerous.  You are feeding into the house wiring and on out into the power company lines.  It is 'safe' if you first turn off the main breaker, but consider what happens if you forget to do that?  Having a proper transfer switch is really the only way to go.  Or just extension cords to key appliances from the generator.

Quote

If I back-feed 120V-30A from the Onan 4000 into that outlet through such an adapter, I think I am supplying power to only one of the two hot wires back to the house.  Oh well.

Ron, back feeding into a house receptacle like that is against code and potentially dangerous.  You are feeding into the house wiring and on out into the power company lines.  It is 'safe' if you first turn off the main breaker, but consider what happens if you forget to do that?  Having a proper transfer switch is really the only way to go.  Or just extension cords to key appliances from the generator.

I do realize the importance of killing the main house breakers (200amp service) to isolate the house from the power company power lines.  That does require serious discipline.

A power transfer switch associated with the main house is more than I can handle as well as not wanting to compromise my main house by adding an electrical doohickey in there.  I was primarily trying to come up with a method to run the house furnace and the only place to easily provide power to it, is through the main panel, gaining other benefits for the fridge and such from that setup.

I suppose I could wire an outlet for the furnace and use an extension cord for it.  But I was trying to benefit a bit more.

In the new house I insisted they install a "priority circuit panel".  This is a sub panel of the main that has in it all of the circuits that would be run by a generator.  Lighting (all LED), freezer, refrigerator and a few plugs here and there.

The panel has a transfer switch so it is either fed from the main panel or a generator input receptacle located outside.  The plan is to run that panel from the generator in the cruiser or from a separate generator that can left to run outside and plugged into the outside receptacle.  Everything wired to code, inspected and approved.

The problem with using the PC generator is it is 120 only so it will power only one side of the priority circuit panel where a real backup generator would power both.  Still it will work and that is what I have in place for now.  I may eventually buy a separate generator but its OK for now.

John, that is an excellent approach, and a new construction gives you the perfect opportunity to set that up.  With my past experience, if I were building new, I would absolutely use a similar approach.  Don't know what you can expect in your area regarding power outages, but like any other emergency they normally occur with little warning.  Ever since ours was out for thirteen days with that unprecedented ice storm in 2002, I've understood that being prepared ahead of time was the right answer.  I was successful in grabbing a generator locally fairly early in that incident, but within a couple of days there were none available in a large radius.  Fuel even became a problem because many gas stations didn't have auxiliary power.  It's interesting that an adequate generator for occasional emergencies can actually be one of the less expensive items of a quality installation like the one you have.  As I mentioned earlier, a 5 or 6 KW 240 volt unit is only about $500, and you can get a larger one to carry everything you possibly need for not too much more.  For that outlay, I wouldn't bother to try to harness the Onan in the PC.  I keep my emergency generator drained of fuel and under cover, and when I needed it for a 24 hour outage only about a week ago, I pulled it out, checked oil and spark, fueled it up, and it busted off on the first crank after sitting for multiple years.  Our electrical service here may be more susceptible to issues than yours, but my vote is to go ahead and set up for it before you need it (just my two cents).

All the best,     Mike

Quote from: mikeh on December 14, 2020, 01:04:57 pm

Quote from: Ron Dittmer on December 14, 2020, 11:14:20 am

This is a very interesting subject.

I have wondered if there was an easy way to jury-rig something.  In my head, I have wondered if this would "safely" work.

1) Flip "OFF" the main house breaker(s) to isolate the house from community power.
2) Turn off every small breaker that distributes power throughout the house.
3) Plug the PC generator into my 30amp outlet in the garage, but I wonder how to output 110V-30amps direct from the PC generator.
4) Turn on only one house-distribution breaker at any given time.
- Run our gas fired forced-air furnace until the house warms up.  The 110V power required would be only for the furnace blower.
- Flip breakers to run the kitchen fridge until it shuts off.
- Flip breakers for other purposes as needed.

Being on a private well that requires 220V, that seems to be a "bust" just like a/c, but everything else just might work.  Having our house 100% converted to LED light bulbs throughout should also make a difference.  Where we live near Chicago, the focus is more on keeping the house warm in the winter rather than cool in the summer.

Does anyone know how to output 110V-30amp from their PC generator?

Ron,

The short answer to your basic question of "can this safely work" is yes.  But it must be done with caution and complete understanding to meet the "safely" criteria.  To begin with--it is truly "jury-rigging" as you say; and it is certainly not to code.  And any electrical modifications that fall into the category of "jury-rigging" are inherently unsafe and dangerous unless you absolutely know what you are doing.  Supplying auxiliary power to your home should absolutely be done through a transfer switch which, if properly installed, will protect your home, your auxiliary power source, and the community power line feeding your home.  However I do provide emergency power to my home safely from an auxiliary generator through a back-feed type connection, which is essentially what you describe.  In my case, it is a full 240 volts, and I energize my entire main panel.  My generator is only about a 6KW unit, so it can't carry my central air conditioning, and I do monitor loads, but everything else is operable.

Your last question of how to output the PC generator is answered in my and especially Volkeman's comments above.  You would need to tie in to the transfer switch on your PC to access the full generator output, and wire in a receptacle that will let you connect a 120 volt, 30 amp cord set to your garage outlet.  With your house main breakers switched "OFF" to isolate you from community power (absolutely critical, and the first thing to do), you would then back-feed to your main panel through the circuit breaker that feeds your garage 30 amp circuit (that breaker must be "ON").  One limitation that you may not have considered is that since you are only feeding in 120 volts, you will only energize the one side of your main panel that carries the circuit breaker for your garage circuit.  Other breakers on that side of the panel will have power, but none of the breakers on the other side of the panel will have it.  It will come down to "luck of the draw" as to which other house circuits are on that panel side.  That's the advantage of a 240 volt capable auxiliary generator--in that case, with the same back-feed process, you feed the main panel through a 240 volt breaker, which energizes both sides of the panel.  In my case, I installed a 240 volt 60 amp sub-panel in my garage for outside power and lights, and that's where I tie in the generator.  With the main breakers to my main panel switched OFF, and the 60 amp breaker to my sub-panel switched ON, my main panel has 240 volts back-fed from the sub-panel to all circuits.  My generator breaker protects that feed, but in practice, I still keep my high amperage 240 volt breakers (A/C unit, electric dryer, etc) switched OFF to prevent accidental overloads.  Even the small 6KW generator carries everything else easily (including my NG central heat blowers), so can remain pretty normal during outages.  Last usage was only about a week ago, when we had a 24-hour outage on our rural electric cooperative system, and it was nice to have normal heat and power.  In 2002 we had a severe ice storm and our outage stretched to 13 days in our rural area, that's when I first acquired the generator and established the hook-up.

Mike

I found Volkemon's Transfer switch receptacle post.  I will look into that.  I thank both of you.

About my particular situation.  I have a wall outlet like this right by the RV over-head garage door.  Now I am thinking I have a 240V receptacle there.


Typically when I plug my PC into it, I use an adaptor similar to this.


If I back-feed 120V-30A from the Onan 4000 into that outlet through such an adaptor, I think I am supplying power to only one of the two hot wires back to the house.  Oh well.

Project #1 is to get a 120V-30A receptacle wired off the power transfer switch inside our PC.

It is too bad Onan did not include direct power outlets on the generator like a normal generator has.

Ron, you are correct.  Based on your illustration, what you have is a 50 amp, 240/120 volt receptacle in your garage wall.  It should be fed from a 240 volt, 50 amp breaker in your main panel.  The adapter you are using for your RV is allowing you to pull 120 volt, 30 amp power from that receptacle.

If you were to back-feed your main panel through that receptacle, as you say you would have the option of back-feeding 120 volts from your PC Onan (or other 120 volt source) using that same adapter, or feeding 240 volt power from an auxiliary 240 volt generator directly to the wall receptacle.  In either case you would have to have your 200 amp panel mains OFF, and the breaker to that garage receptacle ON.  No way can I argue against JATRAX's comments that the back feed approach "is against code and potentially dangerous", or that having a proper transfer switch is the correct way to go.  Both statements are certainly true.  Doing it the "jury rig" way will definitely work, but there is no margin for error.  It depends entirely on the person making the hook-up to not make a mistake that can create a big problem.

If you are seriously considering this, I would definitely consider buying an auxiliary generator capable of 6KW or so minimum output at 240 volts.  The $500 or so that you will spend will offset the need to try to modify the PC (not a simple project), and you gain the advantage of having your entire main panel energized instead of only half the circuits (which may not include the ones you most want). I would still keep the 240 volt breakers off, unless you buy a 10-12KW generator set.  If your existing receptacle is properly wired (I bet it is), it would support 12KW input (which would be a 50 amp service).

Mike

I suppose I could wire an outlet for the furnace and use an extension cord for it.

Ron, honestly the best solution is to do exactly that.  If your furnace is hard wired change that to a receptacle and plug it in.  When needed unplug from the receptacle and plug into the extension cord.  List out the things you need to power: furnace, freezer, refrigerator, etc.  Then buy cords that reach from where the generator is set up to the appliances.  Put those in a plastic tote with flashlights extra batteries, etc.  Now you have an emergency plan.

Ever since ours was out for thirteen days with that unprecedented ice storm in 2002, I've understood that being prepared ahead of time was the right answer.

In 2011 a storm raised the river level and cut the road just down from our house.  Our neighbor's house went in the river along with the road.  We had no power for 15 days, and no road access for 30 days.  Fortunately we did have a generator which was wired up to a simple transfer switch and sub-panel.  But carrying 5 gallon cans of diesel in every day for two weeks was an experience I do not want to experience again.  We had to rent a car and put it on the other side of the cut and hike out almost a mile every day to get to work, then buy 5 gallons of diesel and hike back in every night.

Being prepared for 2 weeks cut off with no support is now a key priority for us.  And a lot of things we did in the new house are focused on that.

Quote from: Volkemon on December 14, 2020, 12:02:00 pm

Quote from: Ron Dittmer on December 14, 2020, 11:14:20 am

1) Flip "OFF" the main house breaker(s) to isolate the house from community power.

""Turn off every small breaker that distributes power throughout the house."" 
TURN OFF THE BIG ONES TOO!!! THEY WILL BACKFEED ONE LEG!!!

Did I not cover that one?  Or am I missing something I need to think about?

You did say flip off the main breaker, but then you specify 'every small breaker...' 



in the image above, you can see the main breaker at the top, some houses have it separately outside. This indeed should be shut off as you stated.

Then there are the ones that distribute the power through the house. There are five 220V or  'Big Ones' , and fourteen 110V or 'Small ones' on this panel. 

If you only turn off the small ones, the big ones will still be making connections from the one leg you have powered. So thats why I was adamant about turning off the big ones as well as the small ones. Hope that makes it a little clearer.  As it has been well said now, we are dealing with a rather dangerous way to power a house in emergency situations.  I do NOT want anyone following this thread to be mislead and believe they are safe. Abundance of caution, if you will. I would rather have that than have unclear directions that can kill.


*************************************************



 

Volk,

That's why, in areas where it's available, natural gas is heating is typically significantly cheaper than electric.  Certainly here in Oklahoma, and even at the higher prices for NG of today.  In small systems (hot water heaters, 30K BTU open flame free-standing heaters, even the 50K BTU dual wall furnace in my grandson's house), there is no electricity used at all.  Heat flow is by convection, and in standing pilot systems, a 750 millivolt thermopile heated by the pilot provides all the energy needed to hold in the pilot safety valve and activate the solenoid in the main gas valve as called for by the thermostat.  In larger, more sophisticated units, such as my central furnace and 2 Lucky's unit, 120 volts supplies the control systems with the gas valve/thermostat circuit powered by 24 volt transformers, but power draw is still almost negligible.  In his case there is no blower, but there are circulating pumps; my unit being forced air and 5 ton A/C uses the same 3/4 HP squirrel cage setup as yours.

Mike

AWESOME!  NG is truly a boon to those who can use it. Thank you So much for the explanation Mike.
 

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.

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.

A custom cable will certainly power up both legs of the box.   

And I would not normally beat a 'dead horse' but your last statement makes me wonder if I communicated correctly.

I did acknowledge that you are powering off the 'main breaker', 200A in your case.    In our house, those breakers (2 @ 150A) are located outside near the meters. Our inside panels are NOT like the panel I pictured before.  So in our inside boxes, and maybe for others also, there are small and big breakers. And none are the main breaker.

The issue was not specifying to turn off ALL the individual breakers that distributes power throughout the house. Not just  '"every small breaker that distributes power throughout the house"" like you said, which would imply that leaving the big 220V breakers right next to them on is OK.  I am now guessing that your main house breaker is inside, like the picture I posted before. So for you, there is one BIG breaker, and everything below is 'small' be it 220V or 110V.

Just like in our campers, different people may have different setups in their house. If I am told 'just connect the hose to the camper, turn the valve to the correct position, and your water tank will fill".....  that wont work for me in a 2006, but work fine for another person with a 2013 who is giving the advice.  I am merely stuck with no water.  No harm done. 

With the breakers, should someone have a different setup in their house, NOT turning off the 220V breakers (Only turn off the small ones..) it could lead to damage or possibly injury. I would rather have people think I am 'mansplaining' ( Overexplaining? or insert your preferred term... ) than mislead someone with a different setup than others.

I am 99.999999999999999999999999999999999999999999%  sure you get it Ron.         I think also of the casual reader that is getting information here that may just take words at face value.   


This thread has been GREAT for exploring the subject. What fun. Thanks to all.