Page last updated Nov 13, 2008 @ 09:07pm

FAQ Generators

This page lists frequently asked questions and answers about generators.

  1. Q: I'm interested in obtaining an automatic generator for my home that will start whenever utility power is lost.  What are the costs for such an installation?

    A: Automatic standby generators ARE available but are much more costly than non-automatic systems.  The reasons are due to the complex automatic controls and automatic transfer switch, the larger size that is required, and the significant electrician time involved to install such a unit.  Costs begin at about $4,000.

  2. Q: I own a Browns Gas Generator which generates 2,000 liters of Browns Gas per hour and which runs on electricity. The power required is 240v (220) and 50 amps (12,000kw minimum).  My Shop/Barn is wired to handle my needs but I need to become portable and I need a dependable portable generator that will easily provide the power necessary and that will easily fit into a trailer.  What generator do you have that will service my need and what additional devices do I need in order to make it work properly?  I will not be using additional electrical devices when the unit is operating.

    A: 50 amps and 12,000 watts is a fairly large load to power with a portable generator. There are some generators described on our web site which will meet this size load. These are electric start. See our online catalog for more details. Here are some things to consider: 1) Since this size generator can consume over 2 gallons of fuel per hour you may need to consider the amount of fuel storage required, depending on how  long you generate the Browns Gas. 2) These electric generators weigh hundreds of pounds and so are not easily portable. You are probably going to want to leave it where you put it.

  3. Q: Great WEB site. The site answered many questions, but I still have one big one. I have a vehicle engine that I would like to turn into a dedicated generator to power the whole house. This includes the well pump, refrigerator, hot water heater and furnace blower fan. I had not thought of the inverter idea until reading it on your site. Is there a better way to turn this engine into a regular generator?

    A: Yes, it IS theoretically possible to to attach a large ac alternator to a vehicle engine, but if you are only going to power a single dwelling you will probably spend more money doing it than just buying an engine-generator set. First of all, a vehicle engine is much larger than you need for one house. You would have to get a hold of or purchase a generator such as those designed for tractor power take-off shafts. We can get these, but they start at 25kw and sell for over $2000. That size requires a 45 hp engine. You could power 5 or 10 homes with that! Then you would have to install some sort of speed governor on the engine to maintain a constant 60 Hz output. It would be an interesting project, however.

  4. Q: Naturally, we are concerned about possible electrical outage with Y2K.   However, we are also concerned that the availability of fuel may be limited and that gasoline does not store well. I have heard that there are conversion kits for gas to propane. Can you tell us about this?  Although money is not really a top consideration, we do not want to invest too much for an event that may not even happen! Also, since we are totally inexperienced, how do we determine our actual needs? Any info will be appreciated.

    A: You are smart to think ahead about fuel. Having a gasoline generator does no good without fuel. [See next FAQ about propane conversion kits for portable generators.]   Some generators are designed as multifuel units. We know of at least one manufacturer that makes these but they are more expensive and their production is sold out until next year.  We think it is unlikely any Y2K power outage would be prolonged. To be prepared, we plan on having a few large cans of gasoline on hand January 1st along with full tanks of gas in all our vehicles. We also have a small hand operated siphon pump to allow transfer of fuel from the vehicles to our portable generator.  Storage of gasoline for prolonged periods of time (months) can result in gum deposits and sticking carburators. Adding a little Stabil to the gasoline when it is put in storage eliminates this problem. Stabil is available at most auto sections of stores. Hand siphon pumps can also be found at auto parts or marine retailers.

  5. Q: Are you able to provide your generators with Tri-fuel capabilities. If not, can you convert to LPG or Natural Gas?

    A: We can provide conversion kits for changing small gasoline engines to LP and natural gas.  The kits can be user installed without removing the gasoline components which allows you to switch back to gasoline at any time. The kit that we have works for both LP and natural gas and can be ordered to fit virtually any portable generator. The kit includes the hose and regulator for use on a LP tank. Note however that the use of natural gas reduces the engine/generator capacity about 20%, reduction with LP is insignificant.  See the accessories section of our catalog such as item LPG01.  We also sell a few Winco models of portable generators that are built as tri-fuel units at the factory.

  6. Q: I'm trying to find out what type of generator I will need to hold a party at an outdoor venue.  Typically, we will be running an average size stereo, two or three 20 watt UV fluorscent tubes and a couple of strings of Xmas lights. We may also be running one of those water faucets with hot and cold water off it. I hope this is enough information for you to help me figure this out. Thanks in advance.

    A: The lights and stereo are probably relatively small electrical loads. I'm not sure what you  mean exactly by the hot and cold water faucets. If the water is heated and cooled using power from the generator, this would be the largest load to consider. But it is hard to guess it's requirements without knowing the rating. My initial guess would be that the smallest generator in our catalog (4000 watts) would be more than enough. If this is just for a one time use, you might consider looking elsewhere for a rental generator.  If the water is not being heated and cooled by generator power, you could probably do fine with one of the inverters we sell. This would be a lot cheaper than a generator and a whole lot quieter and easier to set up. However, a vehicle would have to be parked close enough to run an extension cord. The only other possible concern with inverters is the modified sine wave that they produce can cause some noise in cheap stereos.  Hope this helps.

  7. Q: My electrician has looked at what I've tentatively planned and he seems to think placing the generator in the basement and using the furnace and water heater flues is doable given that I go Natural Gas. Am still interested in multifuel approaches or that ability in the future, depending on what happens 1/1/2000.

    A: Even though there are attractive reasons for locating a generator inside your basement and many people have tried it, DON'T DO IT! Here are some reasons why:


    a) All internal combustion engines produce carbon monoxide gas that can leak out of the engine exhaust system into your living space. This combined with the fact that a generator is most likely used during inclement weather when your home will be closed up tight makes this risky. Every time there are widespread power outages there are news reports of people rushed to the hospital and dying from CO poisoning because they ran a generator in their basement or attached garage.

    b) Running an engine inside your home creates an increased fire hazard or risk. Admittedly gasoline is a greater risk than natural gas, but both are a concern when operating an engine. This is why building codes usually require 1 or 2 hour rated fire isolation between an attached garage and a home. This is usually provided by double thick drywall. I presume you would not be building such a rated barrier between your basement and the rest of your home.

    c) Noise is also a concern running an engine inside your home.

    d) Heat could also be a concern. These small engines are not that efficient. If we assume 25% efficiency for a fully loaded 5kW generator, you would have heat losses of 15kW. Some of this would go out with the exhaust gases but a lot of it is removed through the cooling fins and blower on the engine if it is air cooled. For a liquid cooled engine it would be removed through the radiator.

    If you have ever been in a room with a skid mounted standby generator you would see that the radiator fan actually blows air through the room at a high rate. This prevents toxic and combustible gasses and heat from accumulating. There usually are also automatic sprinklers for fire suppression. I recently confirmed all this with a fire protection engineer. So, if you really want to pursue locating an engine in your basement, at least talk to a local fire inspector to determine the requirements in your area. As an alternative, there may be a way to safely build a small metal enclosure around a generator located outside. Some units can be purchased with this as an option.  Also, consider our PowerShelter Kit which converts a garden shed to allow it to house and run a portable generator.

  8. Q: I have a PTO generator 30kW. My tractor produces 30hp.  My question, is that enough hp to run this generator to power my house?  We are on a well pump and have an oil fired hot water furnace.  I know the generator is large enough to power the house, but I question if my tractor has enough power to run it under load.

    A: The power you can put on a PTO generator is dependent primarily on the engine horsepower. However, it will vary somewhat with with the PTO and generator losses. If there were no losses at all, you would get 0.7457 kW per engine horsepower. A more realistic value is 0.5 to 0.6 kW per horsepower. Thus, for your application:

        30 hp x 0.5 = 15 kW

        15,000 watts / 240V = 62 amps

    You can power A LOT with this capability. A well pump, furnace circulating pump, lights, refrigerator, freezer, and many more loads would be no problem for this setup.

  9. Q: I am interested in your DeVilbiss GB5000 generator.  The specifications provided on the web page that describe this item are quite clear.  Would you please tell me the RPM used by this generator to make the 5000 watts of power?  I notice that most generators today of this type have to run at 3600 RPM to produce the advertised power levels.  Is this unit the same, or can it do as advertised using a slower RPM speed?

    A: This engine and generator runs at 3600 rpm as do most of the economical models on the market today. The more expensive models usually operate at 1800 rpm which reduces wear on the engine and prolongs its life. However, to still get 60 Hz out of the set they have to use a 4 pole alternator rather than 2 pole.  For an ac generator set, the engine governor is set at a specific design speed.  Altering this speed will directly affect the output frequency.  If the frequency differs significantly from 60 Hz for any length of time the alternator and loads that are powered can be damaged.


  10. Q: I would like to know what size you recommend for my house, I would like to run my heat pump, well pump, surge pump, and five 50 watt lights.

    A: There is some sizing guidance on our web site including a bar chart that give typical watt values for loads. Lights are no problem because they are usually a small electrical load with no significant inrush or starting current. However, motors are the important consideration due to their starting current.

    If your well pump is a typical residential size, a generator of a 3000 to 4000 watts would probably be sufficient.  Do you know the horsepower rating of the pump motor and it's voltage(i.e. 120 or 240)?  The biggest load you mention is the heat pump. Try to read the nameplate on the outdoor compressor unit and tell us the running amps, starting amps, and rated voltage.  A sample computation is as follows for 19.0 FLA, 83.5 LRA, 230 V:

      starting: 83.5A x 230V x 0.8 = 15,364VA (watts will be less)

      running: 19.0A x 230V = 4,370VA (actual watts will be slightly less)

    As you can see, a large generator with a surge rating of at least 16,000 watts would be required to start this heat pump.  We have assumed a voltage dip to 80% is acceptable in the above computation.  You probably also have a blower motor inside your house that has similar data but it may be hard to get to. Also, do you have and need to operate an electric range or electric water heater? They are big loads too.  Send us some of this data and we should be able to advise you on a recommended size.


  11. .Q: My original plans were to place a tri-fueled generator in an enclosure inside my garage where I have easy access to a NATURAL GAS line.  The gas man who connects my natural gas could exhaust the unit through the wall to the outside.  I plan to wire the output of the generator via a manual 10 circuit transfer switch into 10 selected circuits.  Now I have been considering your suggestion of a gas powered unit plus your add-on conversion kit, LPG01. I note that your description of the LPG01 unit limits it for OUTSIDE installations. Is there any reason that I cannot place the generator inside my garage?

    A: Concerning installing and running a portable generator INSIDE your garage, BE VERY CAREFUL. Many people have been injured or even died from running portable generators inside their homes, usually in their basement. However, deaths have also occurred due to running portable generators in attached garages.  The greatest risk is due to carbon monoxide poisoning, but there is also added risk due to fire. On the surface, the garage idea does seem attractive and might not be as risky as a basement.  But if there is some way you can run the unit outside and keep it protected from severe weather (porch, enclosure, shed, barn, or detached garage, etc.), that would be the safest. If you you still want to pursue the garage idea consider the following points:

    a) All internal combustion engines produce carbon monoxide gas that can leak out of the engine exhaust system into your living space. This combined with the fact that a generator is most likely used during inclement weather when your home will be closed up tight makes this risky. Every time there are widespread power outages there are news reports of people rushed to the hospital and dying from CO poisoning because they ran a generator in their home.

    b) Running an engine inside creates an increased fire hazard or risk. Admittedly gasoline is a greater risk than natural gas, but both are a concern when operating an engine. This is why building codes usually require 1 or 2 hour rated fire isolation between an attached garage and a home. This is usually provided by double thick drywall.

    c) Noise is also a concern running an engine inside.

    d) Heat heat is another concern. These small engines are not that efficient. If we assume 25% efficiency for a fully loaded 5kW generator, you would have heat losses of 15kW. Some of this would go out with the exhaust gases but a lot of it is removed through the cooling fins and blower on the engine if it is air cooled. For a liquid cooled engine it would be removed through the radiator.

    If you have ever been in a room with a large skid mounted standby generator you would see that the radiator fan actually blows air through the room at a high rate. This prevents toxic and combustible gases and heat from accumulating. There usually are also automatic sprinklers for fire suppression. I confirmed all this with a fire protection engineer. So, if you really want to pursue locating an engine in your garage, at least talk to a local fire inspector to determine the requirements in your area.

    The LPG/natural gas conversion kit is described for OUTDOOR portable generator use because there are some additional fire and safety code requirements for the natural gas and LP valve controls when used indoors.

  12. Q: Standby automatic generators I note include an AUTOMATIC transfer switch, which I interpret to mean that it automatically switches the ENTIRE load and there is no way to allow for selective switching of only part of the total load.  Is this true?   This selective switching is possible with the Gen/Tran 6, 8 and 10 circuit MANUAL transfer switches.

    A: Yes and no. Standby automatic generators do switch the entire load that their transfer switch is connected to. However, you can install a sub-panel fed from this transfer switch. Then wire just those essential circuits that you want backed up by the standby generator to that sub-panel. This allows you to minimize the size and cost of the standby generator but provides power to only your important circuits. If the utility power is lost, the transfer switch would disconnect the whole sub-panel from its normal source (a breaker on your existing panel) and connect it to the generator after it automatically starts. Note that this sub-panel is nothing special and could be any standard panelboard sold by home center retailers.  I you need to prevent only a few large loads from running on the generator sometimes you can do this using spare auxiliary contacts on the automatic transfer switch.  This can easily be accomplished by wiring an aux contact into the thermostat circuit on central air conditioning or heat pumps so that when the switch goes to the generator position the thermostat is turned off.


  13. Q: I am contemplating purchasing your GB5000 generator (5000 watts). I have a few questions if you don't mind.  I noticed your comments on side-valve engines especially "ideal for occasional use."  Would the GB5000 be suitable to run continuously over a period of many days (multiple day power outage)?

    A: Generators with side-valve engines can be run for many days as long as the maintenance instructions are followed. We have heard of unattended applications where they were run for weeks except for brief daily shutdowns for refueling and changing of oil. Here is a sample of the manufacturers' instructions, which are probably very conservative.

    For Briggs & Stratton engines (GB prefix), change oil after first 5 hours of operation. Every 5 hours or daily check oil level, clean around muffler, springs and linkage. Every 25 hours change oil if operating under heavy load or in high ambient temperature, service air cleaner pre-cleaner. Every 50 hours change oil. Every 100 hours service air cleaner cartridge, replace in-line fuel filter and replace/clean spark plug.

    For Tecumseh engines (GT prefix), check oil level every 5 operating hours and before each use. Change oil after first 2 operating hours and every 25 operating hours thereafter, more often if operated in extremely dusty or dirty conditions. Check spark plug every 100 hours of operation. Clean foam air filter every 25 operating hours and replace paper air filter every 100 operating hours.

  14. Q: I checked the wiring diagram and it shows my generator to be a dual voltage generator. The 240 Volt duplex outlet is NEMA 6-20R. My question is, do you build a cord set that plugs into both receptacles of the duplex 240 Volt outlet to get the maximum power to the transfer switch or use one receptacle and be satisfied with a 20.8 amp service?  I can fax the wiring diagram if that would help.

    One last question. Is there a concern that if I use the cord set that you recommend, that I will overload the one 240 volt outlet if it is only rated to carry 15 amps?  If the breaker is rated at 25 amps it would seem that I would need some type of cord set that could plug into both 240 volt receptacles so that I would not overload the single outlet.

    A: Received your FAX and finally reached a real person at the generator manufacturer. They tell us the ratings (continuous & surge) for your model generator are: 120V 41.6 amps & 50.0 amps and 240V 20.8 amps & 25.0 amps.  These correspond to and agree with power ratings of 5000 watts and 6000 watts.  They also told us the two circuit breakers are rated 25 amp, which is consistent with the surge ratings above.  The diagram you faxed is very helpful.  It shows that the neutral IS in fact grounded.   It also shows that each half of the 120V duplex receptacle ("tab broken") is connected to separate generator windings and separately protected with its own breaker. However, each part of the 240V duplex receptacle is wired in parallel. This means that you can continuously power the following combinations of loads without exceeding the generator WINDING ratings:
      (a) 20.8 amps from top 120V receptacle and 20.8 amps from bottom 120V receptacle, or
      (b) 20.8 amps from the top 240V receptacle, or
      (c) 20.8 amps from the bottom 240V receptacle, or
      (d) a total of 20.8 amps from both 240V receptacles, or
      (e) any combination of loads from all receptacles as long as they don't total more than 20.8 amps at each of the two generator windings.
    Keep in mind however that the real NEMA ratings of these receptacles is 15 amps for each 120V receptacle and 20 amps total for the 240V receptacles. These should not be exceeded. Therefore, in reality, the receptacles are the limiting components, not the generator windings.  In terms of cordsets and Gen/Tran manual transfer switches here are our recommended options:  20 amp 5kW 6 circuit switch #20216 with 20 amp 3 conductor 25ft cordset #RJB12425 except that plug to be replaced with NEMA 6-20P.  If you want 10 circuits you could purchase the following combination but keep in mind that the meters on the switch are really for a 7kW generator and load should not be allowed to reach full scale: 30 amp 7kW 10 circuit switch #302110 with 30 amp 4 conductor 25ft cordset #RJB10425 except that plug to be replaced with NEMA 6-20P.  Note that the 30 amp cordset will be made of heavier 10 ga wire and 4 conductors so that if you ever upgrade your generator to a 7kW unit with a locking 4 pole receptacle all you would have to do is replace the plug.

  15. Q: I was wondering if you could answer a question for me, are there kits available to modify generators for electric starters?  Similar to lawn tractor starter on my 16HP tractor. It would help those individuals not "strong" enough to pull the rope to start the generator. It would also allow you to use a relay switch located in the house at the panel box by the Transfer switch to start the generator located outside in bad weather (rain, snow, cold, etc.). Any help on the question would be deeply appreciated.

    A: Yes, we have heard of kits for adding electric start to recoil-start generator engines. But they can get pretty involved to install--sometimes the flywheel must be replaced in addition to mounting all the other parts. Your remote starting sounds good but there are some details that may not make it feasible. First, unless the engine has an automatic choke (very few do), you are going to have to go to the engine to adjust it several times anyway. Second, most portable generators are NOT weatherproof and the manufacturers do not recommend leaving them out in rain or snow. The best place to run them would be in an open carport or covered porch. If this is not possible, another option some choose is to use a little shed or enclosure with our PowerShelter Kit. We do not sell the add-on starter kits at this time. Suggest you check with a small engine service center. If you already have a generator, it would probably be easier to sell it and then buy another that already has the electric start feature.

  16. Q: I have heard that the typical contractor generator is fine for power tools, but is not suitable for anything with electronic controls, like the controller on my gas furnace. These systems appear to lack real power conditioning that would provide "clean" enough output for electronic devices. What is you view of this?

    A: The DeVilbiss generators we sell DO state that the alternators are specially designed to produce clean power. Specifically the literature states: "Clean Power: Rotor dampener bars and skewed stator slots reduce electrical interference to one-half the amount produced by competitive models. Electrical interference can damage electronics and make motors operate hotter."  From personal experience we have used another brand generator that does NOT advertise clean power and have had NO problems with three types of computers: 286-16, 486-75 and Pentium 166.  DeVilbiss recommends in their manual (page 7-ENG): "Any gasoline operated household generator will incur voltage variations causing damage to voltage sensitive appliances... Always use U.L. listed voltage protector to connect voltage sensitive appliances (TV, computer, stereo, etc.). Failure to use a U.L. listed voltage surge protector will void the warranty on your generator."  It is our opinion they are being very cautious in this statement. [We have now added some info on our web site about Clean Power.]   The bottom line is, use a surge suppressor. This will probably be enough unless your electronics is EXTREMELY sensitive to voltage spikes or momentary dips due to motor starting and lacks sufficient filtering on the input.

  17. Q: I am planning an outdoor B3 installation with a GBV7000 portable generator, natural gas converter, manual transfer switch (probably 302110), inlet box, connecting cable. I plan to place the generator in a small shed in a partially sheltered spot about 10-15 feet from the power center in my house.  I  am concerned about any special problems relating to winter conditions for an outdoor location.  How do others handle it?  Since the starter battery will often be at freezing temperatures will there be problems cold starting?  How do you handle the trickle charger for the starter battery, which is generally recommended?  In this regard should I consider going through the trouble of placing the battery with its trickle charger indoors where it is warm and bringing a second cable (along with the generator output) through the inlet box? Could another hole be punched in one of your inlet box to carry a second outlet, for the starting current?

    A: Your proposed arrangement appears sound. Here are some specific responses: Concerning winter conditions below freezing the DeVilbiss rep we talked with had no specific recommendations. They basically felt it was like keeping your lawn tractor in your garage in the winter. Our suggestion would be to purchase one of those small smart trickle chargers that can be mounted right on the side of the battery. It has built-in logic that detects when charging is required and protects against overcharging. Since it is mounted right on the side of a battery it will help keep the battery warm in winter. There are also covers available for car batteries that can help keep the battery warm. Even though you state it is only 10-15 feet away, we would not recommend placing the starting battery this distance from the engine. Every foot of cable will significantly reduce the voltage available at the starter motor unless you use huge expensive cable. Concerning remote starting, it is not practical for this generator set because this engine does not have an automatic choke, and most other portable generators do not either. So, you have to be at the generator to adjust it when starting and as it warms up.

  18. Q: How clean is the power from your generators?  We have had problems with our UPS systems switching rapidly back and forth from line to battery power when running on an old pto generator.  What is the total harmonic distortion (THD) for your generators?

    A: IEEE Standard 519, Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems, Chapter 6 Effects of Harmonics recommends that computers and allied equipment have ac sources with no more than a 5% harmonic voltage distortion factor.  Distortion can be related to the construction of the generator windings.  But it can also be caused by non-linear electrical loads powered by a generator.  Whenever a large portion of the load is non-linear (such as electronics, UPS systems, computers, etc.) THD can become a concern.  A rule of thumb is to keep the non-linear load less than 1/3 of generator kW rating.  For more on THD see our generator sizing page.   Poor frequency regulation can also cause UPS systems to switch back to battery power.  Some UPS systems allow up to + 5% frequency tolerance.  The frequency for a pto driven generator is directly related to the pto shaft speed and the tractor governor setting.  Our generators with Honda engines hold to a 3% frequency tolerance or better.

 

 

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