Episode-794- Chad Kuntz on Back Up Generators — 36 Comments

  1. FYI – This is a question, I am NOT telling anyone to do this, I am playing this out in my head, and trying to understand what the problem could be…

    Listening to the episode right now, maybe he will talk about this, but why always go the transfer switch route? Why not back feed thru a dryer or range outlet?

    If you have a small generator that can only pump out something in the 20 or 25 amp range (assuming that is the max surge current), you throw your main breaker to disconnect from the grid, run the power to your main service panel via the dryer, and then you simply turn off any breakers that you don’t want to use your generator. Order of operations here is very important, never throw the main/grid with the generator still connected since you are the one doing the switching! Do in reverse when you are done.

    Granted I would think you need a 4 wire setup (has your neutral not just hots and ground), not the old 3 wire. All the transfer switch options sounds like at least $500 once you get them and get them installed. Small price compared to the generator, but trying to understand what hazards may exists and have a simple solution.

    As I say this, I would have to pretty much go ahead and go the transfer switch route. Our house is older, and everything is 3 wire.

    • Simple. A transfer switch takes the idiot out of the equation. The house (load) can only be connected to one source or the other. It cannot be connected to both, thus potentially back-feeding into the power grid.

      That said… When we first got our generator I hooked up a switched back feed power cord into my main exterior panel. Yup, completely out of code and unsafe. Once the immediate at-need situation was done I re-worked the system. I now have a whole-house 200amp transfer switch (one of those big panels with the large on-off-on lever). Without going into a lengthy explanation, this was necessary given the electrical system layout and my need to run a well pump.

      I even built a power room for my generator. It is plumbed with the necessary circuits & safety breakers to feed 30amps into the system. It also has exhaust and inlet fans to vent the generator exhaust. With the door shut the room does not overheat in summer, and I cannot hear the generator running from inside the house.

      I keep 100 gallons of premium gas on hand, along with the contents of 5 vehicle gas tanks. Obviously it won’t last through a TEOTWAWKI scenario, but it is more than enough for a common 5-7 day weather related power outage.

      Back to your original question about simply plumbing a generator into your electric panel… My neighbors have a very simple system for connecting their generator. Their back feed circuit breakers cannot be switched ‘on’ when their grid circuit breakers are in the ‘on’ position. There is a low-tech slider bar in their electrical panel which blocks the breakers. They switch the grid ‘off’, slide the bar over the grid breakers, and then switch the back-feed breakers ‘on’. This is an older set up and I have no idea if it is still to code – but it is a pretty simple way to idiot proof a back feed connection.

      • You sound like you are talking about a Interlock This is what we put on our panel this last summer. Not one of the four electricians we had come out to give us a bid had ever hear of it. The one that did the job did a lot of research and said he could recommend this to other people. For us to do it ourselves yes could have but if we ever want to sell it makes things go easier if we have proof of permits and professionals. Not to mention for homeowners insurance.

        In our situation we live in a manufactured home so have a panel outside separate from the house. This is where the main power is. Then the individual breakers are in a panel on the inside of the house. We got a Yamaha 6600 watt gas gen then had it converted to run on propane. (Now to decide on a 250 gal or 500. We have a couple 100lb tanks and several sm tanks. Having a larger tank will enable us to fill the smaller ones as we need.) This will be big enough to run our well freezers and any thing else we may need selectively. In the event of a power outage we cut back on our consumption.

        The next step is to put in small hot water tanks that we only turn on just before we need hot water. For 2 people there is no need to heat 40 gals 24 /7. We have also put in a wood stove so that will provide heat and we could cook on it too as well as use a cast iron dutch oven to bake with if need be.

  2. Here’s another transfer switch option (link to a thread I started in the forum):

    *Standard Disclaimer: No affiliation with said company, no warranty expressed or implied, contents may settle, object in mirror are closer than they appear, if condition persists consult your physician, no animals were harmed in the writing of this post, although the yorkshire terrier next door is living on borrowed time…etc.

  3. Scott what you propose is technically possible and I know several engineer/technician types that do just that. . I just don’t have enough trust in everyone to do the order of operations that you are talking about correctly all the time and possible when under stress or in a hurry. Because of that and being the son of a lineman I could not recommend it because it poses to great of a risk to the lineman working on restoring grid power. A transfer switch be it manual or auto provides that protection with mechanical interlocks. There are kits available that allow what you propose with externally mounted interference devices on an electrical panel. I did not cover them in the interview but they are available.


    • Hi Chad, fair enough, and I agree that it isn’t the safest way to do it for people in the home or utility workers. I guess I wanted to know that there are very simple ways to do this, IF you have your head screwed on straight. I have heard of the islanding effect of people having grid-tied PV systems. I guess some older setups/inverters or bad installs (pick your reason) didn’t automatically switch out the juice from the PV array when the grid disappeared for some reason, and then linemen getting nailed with power coming from the PV. Just as bad as generator.

  4. Scott- and all others,
    …be very careful and get informed before you do ANY mods to your elec system, I believe if you “backfeed” your generator through your breaker box- or specifically your dryer outlet – your homeowners insurance will NOT pay you if you have a fire, even if the source of the fire was not the generator hookup.
    I may be wrong, but that ‘s what I was told by someone in the construction field.

  5. At Scott-Ive been told by certified electricians that this is a bad idea because of safety. I think you ID’d a potential risk and that is damaging your generator or killing someone working on the grid. It may seem simple, but to me its like handling a loaded gun, if you have practice and training with it you will limit your risk, otherwise alot can go wrong, especially when you are under pressure.

    A comment/question for Chad.
    I see the value in a generator for short term emergency situations since its very likely that we can resupply the fuel within a reasonable time frame. What happens if its a bigger failure of society and fuel costs go up? If Im forced into a long term situation, it would cost thousands of dollars in fuel for a generator. Why not just go the solar/battery backup route. At least that has a more tangible ROI? I realize the initial investment is cheaper for a generator, but in the long term it would cost more correct?Just a thought, I look forward to your response since you are much smarter than I am with this stuff! It was really cool of you to volunteer your time to help all of us so thank you very much.

  6. Rob – I have not put a lot of thought into a long term situation. I just feel a long term break down of society in my lifetime is a likely enough senario for me to worry about. Also I live in a northern latitude that solar doesn’t make much sense for me.

    I will freely give my opinion on solar and wind generation systems. Photovoltaics just are not to the point where I see a RIO. By the time you purchase panels, batteries, charge converter, and inverter there is just too great of investement for me to justify it. As far as wind I don’t even feel it is economical on a commercial scale without government subsidies much less on a residential scale. I had talked to a salesman at our state fair about an installation at my home, and realize in ND we are called the Saudi Arabia of wind resources. When I calculated the ROI it ended up to be 30 years or more with no maintenance. I know the maintenance costs will not be zero and in 30 years the equipment will be worn out. So I don’t see that as a viable solution either. If I were to consider a long term situation I would have to go with a generator and a way to produce my own fuel be that bio diesel or alcohol. I think investment in a system of that type would have a better RIO. Both for using it in your vehicles now and to provide a reasonable amount of electrical energy as well. One thing to keep in mind if there is a total breakdown of society many of the things that consume so much electrical energy in our lives now will be worthless bricks and we could get by with some lighting, cooking, and heating requirements.


    • ” I just feel a long term break down of society in my lifetime is a likely enough senario for me to worry about.” Did you mean NOT enough to worry about?

      I would agree mostly with you on solar, and 100% on wind. But, only to the point that it assumes a large full house backup. You make a good point of reduction in energy consumption for a long term situation since reality will settle in, but Im not confident of our ability to get fuel at an affordable price which is a constant input. As with Jack’s experience and generators, Ive had the same issue with salesman overdoing it and not really understanding the needs. As a result I met with a guy that does solar systems for the Amish on a small scale, and he has educated me on a lot of the issues. I will be working with him on a small 2,000 watt system with battery backup and solar charger. This is enough to ensure my security system will go for a long time and I will be able to cook and run my fridge. Again, this is designed more for long term, but is usable for short term as well. I became very discouraged after hearing numbers like $15,000 plus for a solar system, til I researched it and found that it was overkill for what I needed for a long term situation. I will most likely get a LP generator too at some point since I have a 500 gallon tank for my back up heat source. Thanks for your input and wisdom.


  7. I didn’t hear in the interview, but are there generators that will run on ethanol/alcohol? And if so, what are their pros and cons? And are they a lot like a gasoline generator as far as safety, exhaust venting, rotation of fuel, etc.

    I barely know that a rodent in a wheel isn’t under my hood, running my car – so please go easy on me.

  8. Rob – Yes I meant NOT to worry about. It sounds like you have made an informed decision. One word of caution I want to make sure you remember when sizing that battery backup. The 2000 Watt solar system is probably nameplate rating. That assumes perfect conversion, perfectly clean panels, perfect sun angle, etc. If I was sizing those batteries I would assume the 2000 W panel array would supply 1000 W on average. That goes for any energy system that has a variable input such as solar and wind. It is easy to put a nameplate on something that it performes to those specs in a lab setting.

    • You are absolutely right about it not being 100% conversion. Ive doubled my needs to get to the 2000, but maybe I should go higher with the inverter…which in my mind is the critical part. Adding more batteries is easy, having to return the inverter is another story! Thanks again for your input.

  9. Our electricity is supplied by a new company, and as of last month, my bill has doubled. Its moved into the unaffordable range…I’m pretty conservative with my power use, but have an all electric house with well pump/hot water heater that seem to be a huge power hog. I’ve been toying with the idea of going off grid with a generator, and not running it continuously, just when I need it, working my schedule around so that I don’t need available electricity 24/7. I heat with wood, and can cook on my stove too. The question I have is, does this make sense economically? It SEEMS like they take very little fuel to run. Can power be stored in battery banks? Thanks for your input.

  10. Hey Jack- just a heads up- you have two episodes 792, so this one is actually 794.

  11. Hey Chad, Jack, or anybody that could provide insight on this…. I have one main question that may be hard to explain. This may be more of a mechanical/engine performance question than electrical, but here we go…

    When a generator is running, what can we do with the “wasted” electricity? I know it is not nearly that simple to determine how much is being “wasted.”

    There is an “optimum” spot for an engine to run. Taking into all the variables that an engine has, there is one sweet spot where an engine is at it’s most efficient point from a fuel usage standpoint. So how do we figure out at what point of power consumption from the generator are we at the “break even” point to where we’re not wasting more electricity than we are fuel? This concept is very difficult for me to explain and it’s frustrating!

    Does any of this make sense? If nothing else, answer this: If you run your generator just to power your freezer, what else could you do with some of the electricity so it’s not just wasted?


    • Im not positive of this, but there is a product that is supposed to “recover” wasted energy from motors and store them in a capacitor. I don’t know if they are worth it or not.

    • It doesn’t work that way biker. The more load you put on the generator, the more gas it uses. The governor gives it more gas to keep the rpms constant. You can hear it happen, just like on a lawnmower.

      You can look on the specs for fuel usage on a generator and it gives you them at full load and a percentage.

  12. Biker250 – I think I understand the question and I don’t have a real good answer. Kind of like a car gets its best mileage at X mph and worse mileage less than or greater than X. To find that point would require measurements of fuel usage at various known loads. But then when that known load was known you would have to have a device that could push energy to a battery system on a variable and dynamic basis. I think the cost and complexity of such system would outweigh the benifits of that system in all but the longest term senarios. I think if your loads were that small of just running a freezer the inverter model generators I mentioned would be the best solution. Again with that design the engine does not have to run at a set RPM. It only needs to supply the power required to supply the load no more no less. The inverter compensates for voltage and frequency with power electronics.

    I hope that answers your question.

  13. Ellen – The answer to your question requires more background information. Your utility company bills you in KWH and should have the cost listed on your monthly bill. I did some quick back of the envelope calculations, think running a diesel generator like you suggest would cost you approx $0.40 a KWH. But as Steven Harris pointed out in a previous show natural gas is very inexpensive right now. I calculated you could generate electricity for about $0.11 per KWH with a natural gas generator. Now if those KWH costs are comperable to the utility cost it may be worth it. Some things to remember, if you run a generator in this mannor you want to make sure it is rated for a prime or continous rating. Most are rated as standby and have a much shorter life span than those rated for prime or continuous duty. Also realize that fuel would be a small component of the cost of running a unit like this. There would be maintenance costs associated with running a machine that amount of time. It would be like having your car run for 4 hours per day. Obviously engines will wear out with that type of use or require overhauls. I would estimate a small diesel engine to last 10000 hours with good maintenance and a natural gas engine to last 25oo hours? But engine life is out of my area of expertise.

    Hope that helps.

  14. Perfect timing!!! I have analysis paralysis and was leaning heavily towards this Sportsman 7KW Propane Generator

    Any thoughts? What about buying two 4KW generators and using them together when needed? Is that a good idea? It would actually be a little cheaper for the propane 4KWs. Do propane generators need to be exercised?

    It looks like Honda does not make a complete generator large enough for my needs. Do you still recommend generators with a Honda engine only from other manufacturers? At 2 1/2 times the price of others?

    If a generator doesn’t have the regulator, inverter, meter or other devices that Chad recommended, can they be added later or do they have to be built in with the generator?

    The limiting factor is my 1000ft deep well. The well company said that it needs 6400 watts to start and 1600 to run. I also want to run the fridge, freezer, septic pump and furnace. I got a quote on a 8KW Generac, but it was over $5000 installed for everything. My wife and I can tough it out and plan for showers and turn things off. We just need running water, hot water and furnace. Also, a generator only gets about 45% of its cost back when a house is sold, per MSN Money. A rural area would probably get more back, though.

    Thanks for the great info! I really, really appreciate it!

    • I will try to answer your questions one at a time.
      1. I can’t say anything good or bad about the unit you linked to. I will say it seems loud and also the fuel consumption is listed at half load I didn’t see full load ratings so it would eat up a 20lb propane tank in about 4 hours or less.
      2. Some manufactureres allow a cable to be connected to 2 generators to connect them in parallel. If that is not offered then I wouldn’t recommend it for your application as 1 load is larger then the output of 1 generator therefore you would need both synchronized and sharing the load to start your well pump. If you had smaller loads that could be split up between 2 generators then that solution would work.
      3. Yes all generators should be exercised periodically.
      4. Honda makes a great engine but there are other reputable manufacturers. Don’t base your decision solely on that. I like Honda inverter generators but non inverter there are many good options.
      5. The unit you are looking at has an automatic voltage regulator. It would probably difficult to integrate it with an auto transfer switch. I am unsure what other types of meters you would like to add but a volt meter and frequency meter could be added rather easily by connecting to one of the receptacles to measure a voltage signal.
      6. I would do some shopping around on the web for that Generac unit and see if you could do some of the install yourself with the exception of the gas plumbing and electrical connections. You may be able to save several hundred $ that way.

      • Thanks for answering my questions, Chad! I really appreciate it and did not realize how loud the generator is and how fast it consumes fuel. Thank you for doing this show and for taking the time to answer my questions.

  15. Regarding propane generators….

    I have a 2500w propane generator on my truck camper. Built-in, remote start, and meets the needs of a camping generator. It does not require me to carry any additional fuel types either.

    That said… It is one cantankerous generator! It will not run with the air filter removed, and is even very fussy about how the air filter is positioned. Once it is fully warmed (30+ minutes), it will occasionally miss under heavy load (A/C).

    I had a problem with my propane system where oil was being produced in the system. I learned that propane is a by-product of refining oil. When propane sits, it will continue to refine itself. As a result I ended up with oil in my lines. I had to remove all the fixtures and then blow my lines out with solvent. Unfortunately a little bit of that oil got into the generator and it is has not been the same since.

    Anyway, to provide feedback for Jack based on the episode… I would not go with a propane generator for my house. They are just too fussy to keep working properly. And, in my experience, propane also has storage problems like other fuels. A diesel generator spinning at a comfortable 1800rpms is going to be a lot happier than a gas/propane generator screaming along at 3600rpm.

  16. @Marty

    “I learned that propane is a by-product of refining oil. When propane sits, it will continue to refine itself. As a result I ended up with oil in my lines.”

    WHAT? Either I misunderstand you completely, or you have been told 100% pure nonsense. If it “continue[d] to refine itself”, it sure wouldn’t go BACKWARD to oil! It would devolve from propane to methane, a simpler molecule.

  17. Here’s a generator idea that I implemented. So far it has worked very well for my situation..

    I already owned 2 ~4500kw gasoline generators and decided it made sense, in an emergency situation, to have a better alternative, long term, or storable fuel solution. I purchased a couple of tri-fuel conversion kits from this company.

    I’m sure there are several other places to buy these kits, but this one has worked great for me during all my testing and regular use.

    The kit was fairly easy to install and requires about a knowledge level of at least a 3 out of 10 in mechanical/small engine repairs.

    In the mid sized town where I live, natural gas is available as a metered pipeline hookup to the home with no external storage tank needed. I piped a quick disconnect natural gas outlet to my basement, and also plumbed a flexipipe exhaust hookup, ran through a truck muffler, vented to the outside of my home. (Before you say anything, YES, I have a CO2 detector near it, and at 2 other places in my home.) When the generator is running, you can’t even hear it more than 30ft from the exhaust outlet. Mate all this to a manual disconnect breaker switch, and necessary systems can run even with a power outage for as long as the natural gas lines are working, and natural gas seems to be one of the last things to fail in a short, 1 day -4 week, outage.

    I also have a few 20 gal tanks of propane available if natural gas isn’t available, which give me plenty enough time to decide if I need to bug out or stay bugged in.

    It’s not a cheap option, but is probably cheaper than buying another generator that will only run exclusively on LP/NG.

    Now factor something unlikely, like a teotwawki event, into the equation… Make yourself a wood gasifier, or a biomass digester, and you have a very sustainable source of fuel for your emergency electrical needs.

  18. Caught up with a bunch of TSP episodes from last week over the weekend. This was one of my favorites. Been a long time in coming (I can remember Jack saying he wanted a guest to talk about generators more than a year ago so thanks Chad!). I made an investment in a 7500W portable propane generator and a manual transfer switch/breakout box about 2 years ago. I also have a 2500 W gas generator (that had to stand in for the 7500 W in one weather related event – 2 is 1 and 1 is none!). For my next step I would like look into replacing my manual transfer switch with a ‘hybrid’ box like this one from a TSP sponsor:

    The idea being that I have one panel I can tie in my existing generator plus a future small set of solar panels all running batteries and then the batteries running an inverter that ties into a sub panel of circuits I want to run in my house. Other than cost, are their downsides to this approach?

  19. Jack, you mentioned on the show that you have a well and need a generator to power it. We also have an old well that was put in in the 1960s. How much generator power is needed to keep a well running short-term?

    • There is a pretty big draw on start up and then it drops off but it is significant. Keep in mind my well is over 600 feet so I have a pretty heavy draw pump. I think the start up draw is in the neighborhood of 1500 watts and running watts are about 500-600, but I am not positive on those numbers off the top of my head.

  20. Chris, the Xantrex PowerHub 1800 says it has a built in inverter. I would be concerned that the inverter doesn’t line up with what you or I would need. I would definitely request more information about the builtin inverter to figure out whether it works for you. With the value of the inverter and 100AH battery (at how many volts?) factored in (assuming you don’t already have an inverter) it might be a pretty good price.

  21. Chris, it would probably make the most sense to figure out the exact components that are in the PowerHub and figure out what it would cost to build it yourself. It would be better to solve the same problem yourself with hardware that you have evaluated and are sure you need. In the end, it would allow you to fix one part of the system if it went bad instead of needing to find another integrated solution.

    • James. Agree. Although Xantrex does make larger ones too. Is there a single device that will both act as an inverter and charge controller with multiple inputs for batteries (Grid, genny and solar)?

  22. Thanks Jack. Think our well may be about 275 feet deep based on other wells in the area. Uses a 230 volt pump. Would like to put in a manual hand pump as a backup. Wish I knew more about it, esp. being that the local well co. charges $90 an hr. to come out.

  23. Hey guys, just wanted to add one more option. Instead of a generator I use a portable welder/generator. It cost me about a third more money than a generator but it can be used for more than one thing. I have it mounted on a small trailer so it is portable. I have not done it yet but you can purchase a tri fuel kit (as stated in an earlier comment) so you can run it on gasoline, propane, or natural gas. That way you have 3 options for fuel in an emergency situation.
    We had an ice storm a few years ago and it worked great. Since it is portable I was able to take it to my inlaws once a day to run it for a few hours to keep the fridge and freezer cold and give them a tank of hot water. Some of the reasons I went this route is if I bought a generator only it would (hopfully) very rarely be used. I can and have used this for my own projects and even made a few dollars doing welding for others.
    Just wanted to throw out one more option for everyone to think about. I know it wont be for everyone but it works great for me.