Portable generator question.

Discussion in 'The Bench' started by eagleguy, Feb 18, 2021.

  1. Mike B in SC

    Mike B in SC Well-Known Member

    If any of you guys do this yourself, please make sure you correctly size the wires. I had a friend burn down his hunting cabin by putting #14 wire on a 60 amp breaker. Luckily nobody was in it at the time but we had all been sleeping in it the weekend before.
  2. Mike Trom

    Mike Trom Ugg

    The kit I used recommended #12 for less than 100' with up to a 5500W generator
    #10 for less than 100' with up to a 7500W generator.

    My run was less than 10' and my generator is 5500W so I used #10.
    philbquick likes this.
  3. cobravii

    cobravii Well-Known Member

    I am in the process of doing the same thing. The big thing to remember is to make sure you don't let it feed back into the grid. It could kill a lines man. I'm not done hooking it up but here is a pic of the transfer switch I am using. It allows me to pick which circuits I want to power.... 1837E452-B32A-4A64-B4C1-B487C44B8AF3_1_105_c.jpeg
    Last edited: Feb 19, 2021
    Briz likes this.
  4. eagleguy

    eagleguy 1971 Skylark Custom

    Thanks for the info guys. In the end I bought a factory refurbished Westinghouse 7500/9500 generator for $600. My new home already has a 30amp generator power outlet being installed next to my outside meter specifically for direct connection to my service. 50 amp would have been more juice but would not have made much difference in what I could power according to the electrician. No power will go back into the grid.
    cobravii, rkammer and OldDrummer55 like this.
  5. 73Electra 225

    73Electra 225 Well-Known Member

    Some advice that many are not aware of regarding portable generators and electronic equipment. Most portable generators, unless its an Inverter style, do not produce clean power, i.e. variations in the rpms of the engine will cause variations in the line voltage and Hz frequency. Anything that is computer based will not like this. So, your computers obviously, but also modern TVs, and many other SMART appliances can be damaged if run directly off of dirty generator power. The way around this is to have double conversion battery back ups. Normal battery backups that many of us have are NOT these and should NOT be used on generator power. You can easily kill a standard battery UPS this way as the generator fluctuations can cause it to click on/off over and over. A double conversion backup will convert the dirty AC first into DC, then back into clean AC, thus protecting your equipment. They cost more, but if you rely on portable generator power often, it would be a wise investment.
  6. Briz

    Briz Platinum Level Contributor

    Is this why my Microwave sounds funny when running on the generator?
    6769RIV likes this.
  7. John Codman

    John Codman Platinum Level Contributor

    We bit the bullet and purchased a 22K automatic generator that has a 250 gallon Propane tank. It will run the entire house, but has an automatic load-shedding feature that will (if necessary) drop the dryer, water heater, and/or electric stove. The load-shedding feature was a part if the installation package; if it wasn't, I would not have purchased it. Our water heater is a hybrid, but runs in "efficiency" mode only. It uses very little power. The electric stove is an induction unit and also isn't a power hog (although it has a standard resistance heater oven). We wouldn't bake a Turkey during a major power failure anyhoo. I don't think that we would use the dryer either, just to not use the additional Propane. Our generator is a Briggs & Stratton; my only complaint is that it runs for 22 minutes every week to keep the Spiders and other crud out or the air filter and exhaust and to keep everything lubricated. When we lived in Massachusetts we had a 10 KW Generac that has the same Briggs & Stratton engine, and it ran for only 12 minutes per week. The extra 10 minutes is a waste of Propane and annoys the hell out of me. Apparently the run time cannot be adjusted.
  8. 73Electra 225

    73Electra 225 Well-Known Member

    Yes, more than likely.
  9. eagleguy

    eagleguy 1971 Skylark Custom

    I actually bought the Westinghouse vs a Generac because its total Harmonic distortion was better, it ran cleaner and it had less of a chance of damaging sensitive appliances. Of course this is all based on product info, not on real life experience. That said, we will see as I hope I never have to use it. The only way to truly cover all bases was to get a whole home generator but I was not willing to pay the price!

    My old (21 years old) Generac served me well but its main seal leaks real bad and it would run around $500 to fix as it's time consuming and labor intensive. Replacement part question is unknown due to age.
  10. philbquick

    philbquick Founders Club Member

    I agree with you 100%. When I was a field engineer for a computer company, every computer room had a 100 sq ft room next to it with banks of batteries and big power inverters. We had to retorque the nuts on all the terminals once a month. During hurricane Irma I powered my house A/C and all with an 8KW Miller bob cat welder, it was real noisy and here's why: 60 cycles per second X 60 seconds per minute = 3600, so the engine had to run at a constant 3,600 RPM to make 60 cycles per second power. It seemed to run my digital stuff OK except the garage door opener that got locked in some weird mode and didn't straighten up until a ran it on clean power. An inverter type system could use a DC generator to run the batteries then reinvert to make 60 cycles, so, RPM becomes irreverent.

    I recently replaced the carb and fuel tank on my 2.2KW Coleman generator and wasn't sure how to set up the governor so I watched some YouTubes. It turns out the governor is set up according to output frequency. I put a frequency meter on the output and checked the frequency at no load and full load. I ended up with 59 cycles per second at full load and 61 at no load. This generator is on a hand cart so I can throw it in the back of my truck and use it in disaster areas like I did during hurricane Charley in 2004, it also runs my 130 amp welder and I can use it to cut panels off cars in the junk yard.
    Max Damage likes this.
  11. rkammer

    rkammer Silver Level contributor

    My Champion 7KW generator powered my entire house (less the A/C) during hurricane Charlie in 2004 for over two weeks and a newer version of the same generator powered our current home during hurricane Irma in 2017 for over a week. Never had a problem with any of our TVs or computers or any other equipment in the homes.
  12. Andrew Sury

    Andrew Sury Well-Known Member

    I simplified my life last year with a motorhome. I put in a 50 amp service to keep the humidity down and when a storm hits, I just fire up the 22000 kv generator and plug it into the house. Kill the main and it will run everything including the well pump. Storms past I would run it through the dryer plug, but that kind of restricted a lot of stuff.
    The genny is hard on fuel, but the motorhome stores 55 gallon, I have a hundred gallon transfer tank in my building, and it will run on propane.

    And worse case, we can live in the motorhome
    2001ws6 likes this.
  13. stump puller455

    stump puller455 1970 GS 455

    I bought this unit 17500 w installed nat gas conversion kit with the air compressor style quick disconnect natural gas hose A 50 amp plug outside backfeeding the panel through a 60 amp breaker I have to do it all manually shut the main breaker off and then set up generator. I have a kit that holds a big umbrella over the top of the unit in case it rains it’s pretty sweet ... must have a/c and fridge 0346061E-9043-4924-9D82-B8763374B51E.png EC71C800-EE43-4B8F-A6B4-FCA822B4EEDC.png I could do it in less than 10 minutes this virtually guarantees I’ll never get a hurricane again in this area due to the fact I’m ready for it that’s Murphy’s Law
  14. Briz

    Briz Platinum Level Contributor

    Exactly. Have not needed mine since I installed it. However the storm prior was using 2-3 different small generators for different functions and it was a constant battle to keep them gased and running
  15. Max Damage

    Max Damage I'm Working on it!

    Or you will fry an adjacent lineman that is trying to fix your wiring.
  16. philbquick

    philbquick Founders Club Member

    There would be a very remote chance of that happening, it could only happen if your line is disconnected from the transformer and the lineman is working on your line only ( he would knock on you door and tell you he's out there). If it's still connected to the transformer (the grid) the breaker on the generator will trip as soon you turn it on because you would in effect powering the entire neighborhood. To be absolutely correct, you should never back feed the main breaker.
  17. Bogus919

    Bogus919 Silver Level contributor

    I ran a Generac 15k at my house in NH through a 50 amp receptacle with a massive extension cable hooked into an interlock switch on the panel, it worked great and would run anything. I have yet to set it up for my FL home now that I have moved and I am not certain it will run my main AC which is 5 tons but I think it will run my smaller 2 ton unit that is for the second floor. I guess I gotta get that lined out before hurricane season :confused: Anyway, I have a video of my setup on my youtube channel if you are interested. Link is in my signature.
  18. 87GN_70GS

    87GN_70GS Well-Known Member

    I read and thought the same thing. Then I bought a non inverting generator and hooked my o scope up to the output. While not a perfect sine wave, there was no steps or notches or dirtiness that I saw.

    I haven't had any issues running any of my electronics or appliances. I feel any decent power supply on equipment made in the last few decades should be able to function properly with this type of ac waveform

    20200421_143715.jpg 20200421_143524.jpg

    Attached Files:

  19. 73Electra 225

    73Electra 225 Well-Known Member

    I'm assuming it all depends on the generator and its operating condition, etc. I think the battery backups are more sensitive than anything. I know for a fact I have a client that has to unplug them if he has to use his generator as they go nuts.
  20. richopp

    richopp Well-Known Member

    The dealer who sold me my Honda generator had an electrician he used. He came over and installed a transfer switch panel right under my service box and made me a cable at the length I wanted to run the generator outside on the patio. He was pretty surprised that the big Honda ran everything I needed (I have a portable room A/C that I use when power is out) and did not labor at all.

    I think I paid about $700 for the panel and cord...x dollars/foot. Works great, and I don't have a propane tank buried in my yard. Also, about $5000 vs $25,000+ for a whole-house.

    Nothing against whole-house, but I had a young daughter then and did not want the propane. I am used to handling a few gas cans already, so it worked out fine the one time I needed it for 4 days.

    I am moving an hour north where the neighborhood has buried power lines. Not sure their track record on hurricanes, but I am taking the generator and cable with me, so even if I lose power before I get either a transfer switch installed or go for a whole-house now that daughter is grown and gone, I will be able to run everything I need until I make a decision.

    I recommend the new Honda's with fuel injection for a portable; they are strong running and quiet to boot.


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