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Frenquently Asked Questions

FAQ Page - answers to question regarding generators, wattage calculations, transfer switches, portable vs. permanently installed backup and prime power systems. More answers are added regularly by United Generator.com

The most FAQ question to date is "What off the shelf filters fit the Kubota Generators?"

Answer: KUBOTA FILTERS cheat sheet updated 3/6/2017
Kubota Filters for GL7000 AND GL11000 Generators (for the first 2 years or 2000 hours you must use factory filters or you will void warranty. Change oil and oil filter first 50 hours then every 200 hours)
Kubota Air Filter inner Part # 32721-58242 list $43.60
Kubota Fuel filter paper cartridge style outer (gets dirty faster than inner -most used) Part #6C060-99410 list $43.60
Fuel filter paper cartridge style T021-43560 list $6.79 nominal fuel filtration rating is 10 micron
Oil filters for Kubota GL 7000 and 11000 watt models and others as follows:
Kubota Factory Part # 70000-74034 –fits GL: 4500, 6500, 7000, 11000
Kubota oil filter Part # 70000-74034 list $7.87
Kubota oil filter Part # 70000-74034 cross references to Napa Auto Parts 1334 oil filter or WIX 51334 oil filter.
Suggestion: Use Mobil ® Delvac 1300 Super Diesel Motor oil for the engine oil and oil changes. Do not use automotive grade oil.If you need to know quanities, maintenace schedules or frequency of replacement purchase your shop manual here Kubota Manuals

FAQ: Re Generators and Transfer switches

Please be advised that all Manufacturer’s instructions, User manuals and Installation Guides take precedence over all and any of the tips listed below.

The information provided is merely intended to serve as a tip to the generator purchasing. UnitedGenerator.com cannot be held liable for any experience that deviates from what is listed below.


Q: What different types of generators are there?

A: There are many different styles avaulable. Portable, permanently installed, mobile, trailer mounted, recreational, job site, camping, home back up, off the grid primary power source, emergency back up systems, systems designed to work with solar systems and battery banks.

Q: What type of fuels do they burn?

A: Most common are gasoline, propane, natural gas and diesel. Some generators run on bio diesel. Some generators are called dual fuel and burn both propane and gasoline. Some tri fuel generators run on propane aka LP, nautural gas and gasoline.

Q: What is the process I will have to go through to get a generator installed and ready for back-up?

A: The generator process typically involves:

  1. Site Survey by a licensed electrician which includes a wattage calculation (required on larger projects)
  2. Selection of Generator (we help with that decision)
  3. Architectural drawing/ permit (we have ours in house and provide that service)
  4. Natural/LP Gas Installation
  5. Delivery of unit and placement of panel (this may be done before the gas source has been installed.)
  6. Electrical Installation

Q: What should I consider when choosing a generator?

A: Get a generator that is rated for the amount of power that you can determine you will need. Look at the labels on lighting, appliances, and equipment you plan to connect to the generator to determine the amount of power that will be needed to operate the equipment. Choose a generator that produces more power than will be drawn by the combination of lighting, appliances and equipment you plan to connect, including the initial surge to the generator when it is turned on. Surge is the wattage or amperage required to get an electric motor started from a dead stop which can be 1 1/2 to 5 times the running wattage requirements. The running wattage and starting/surge wattage is usually displayed on a data plate on the electric motor. We also have a wattage estimator on our web site available for your review that has common wattage requirements listed for appliances, tools and motors. Sizing Estimator

Q: How much outdoor space do I need for the generator?

A: Make sure you have adequate safe space outdoors to run the generator. In order to provide proper ventilation, some generators require 3-5’ distance on all sides of the generator – check your generator manual for specifics.

Q: Is there someone that can help me decide what generator I need?

A: Call United Generator @ 707-542-8254. If you cannot determine any of the above call us, we are familiar with generators and you can ask for a site survey – we will be able to help you make these determinations. You may also use our Sizing Estimator which contains wattage estimates for many common household appliances; including AC units, tools, refrigerators and even pressure washers. The Sizing Estimator works well for small projects and situations that are limited to a few items but becomes difficult to use as the project grows in size. It does not work well for determining a home back up system.

Q: What is included with the generator?

A: It is important to find out what does and does not come with the generator you are purchasing e.g. Transfer switch, composite pad (if not, cement slab may need to be poured, which may require a building permit being pulled), grounding rod, engine oil, professional start up and testing, battery, battery charger, etc.

Q: Will there be any other costs that I might incur?

A: Other than the cost of the generator, additional costs that you may incur include:

  • Installation cost
  • Gas or liquid propane cost
  • Generator Shipping cost
  • Delivery Truck added lift gate cost. This is a hydraulic platform used to lower heavy generators to the ground when customers do not have a delivery dock or fork lift.
  • Battery cost
  • Permit fees
  • Architectural drawings (if necessary)

Generators come with an installation or owners manual. Be sure to always make reference to the manual if you have any doubts.

Q: How long does a generator take to install?

A: It takes approximately eight to sixteen hours for two men to deliver and install a standby generator. Pre-packaged pre-wired units may take less. This would be subject to a site survey. Most installation(s) includes engine break-in and initial oil and filter change.

Q: Does a generator need maintenance?

A: Depending on how often power goes out the engine oil and filter will need to be changed once per year or more. Prime power generators require oil and filter change every 100 hours.


Q: What is Automatic Voltage Regulation (AVR)?

A: AVR is a feature offered with many different generator models. The power produced by a generator is not perfect, many factors can introduce interference into their output. If unchecked, these imperfections can lead to spikes and dips which can damage sensitive electronic equipment. AVR uses a number of power conditioning techniques to smooth out the power delivered by a generator, guaranteeing safe operation for electronics.

Q: What is the difference between running watts and starting watts?

A: Running watts are the continuous watts needed to keep items running. Starting watts, are extra watts needed for two or three seconds to start motor-driven products like a refrigerator or AC unit.

Q: How can I determine the running or the starting watt requirement for a tool or appliance?

A: First check the data plate on the tool appliance, if the running watts are not listed. You may use this equation:

Watts = Volts X Amps

10 ciruit automatic transfer switchTRANSFER SWITCHES

Q: What is transfer switch?

A: Transfer switches allow switching from a primary power source to a secondary or proprietary power source. Most often transfer switches can be seen where emergency power generators are used to back up power from the utility source when there is a power failure. The transfer switch allows switching from utility power to emergency generator power. The switch is either a manual switch, an automatic switch or a combination of manual and automatic. A manual transfer switch is designed for portable generators. An automatic transfer switch is designed for permanently installed home backup systems. During a power outage, the transfer switches isolate the emergency circuits from the utility line allowing for efficient operation of the generator without back feeding electricity onto the utility.

Q: Why put transfer switches on generators?

A: The most safe and convenient way to run a generator is with a transfer switch. These switches should only be installed by a qualified electrician. Transfer switches have three selections. Generator on ...center off...and utility on. Transfer switches prevent you from having the generator and the utility power on at the same time. Which would mess up the wiring in your home, damage your appliances and generator. When installed properly they will prevent a back feed to the utility lines which could prove fatal to a lineman working on the power lines. The utility transformer is a step down into your home but becomes a step up when fed the other way.

Q: What is the best way to hook up a portable emergency generator.

A: Power inlet boxes are perfect for connecting your portable generator to your transfer switch. You basically install the box just like an external power outlet, just connect it to your transfer switch. When the power goes out, simply start your generator and plug it into the outlet.

Q: What is a Break Before Make Transfer Switch

A: A Break Before Make transfer switch breaks contact with one source of power before it makes contact with another. It prevents back feeding from an emergency generator back into the utility line. One example is an open transition Automatic Transfer Switch (ATS). During the split second of the power transfer the flow of electricity is interrupted.

Q: What is a Closed Transition Transfer Switch (CTTS)

A: Provides seamless transfer switching in less than 1/2 cycle.

Q: What is a Soft-loading Transfer Switch (SLTS)

A: An SLTS essentially uses CTTS technology but actively changes the amount of load accepted by the generator.

Q: What is a Manual Transfer Switch

A: A manual transfer switch is designed for portable generators. Manual transfer switches are operated manually by a human operator pulling on a lever to switch from failed utility power to temporary generator power and vice versa.

Q: What is an Automatic Transfer Switch

A: An automatic transfer switch is designed for permanently installed home and commercial backup systems. Automatic transfer switches are operated electrically without the need for a human operator. They automatically switch from failed utility power to temporary generator power and vice versa as needed. They must be sized to the load, incoming power supply and the generator output.

This section of FAQ is designed to help define some basic terms and answer common question about large generators and generator technology. Generators, especially Industrial and Commercial size ones, can be extremely complicated and intimidating for the beginner.

Q: How does an alternator type generator work?

A: The goal of an alternator type generator is to convert mechanical energy into electrical energy. When a magnet is spun inside a coil of wire (usually wrapped around an iron core), it induces a current in that coil. An alternator type generator (alternator) uses this property by attaching a magnet (called the rotor) to the output shaft of the engine (either directly or with a gear or chain drive) and spinning it within one or many coils (called the stator). As the rotor spins, it induces an alternating current in coils of the stator. One can control the the frequency of the output by changing how fast the rotor is spun.

Q: What is the difference between a 2 and 4 pole generator?

A: First, you should be familiar with how an alternator type generator works. Most small generators use a 2 Pole setup, this means that the generator spins a single magnet (which posses 2 poles) inside of a coil. In order to produce an AC signal at 60Hz, this magnet must spin at 3600 RPM. This is why most small engines, which can run at higher RPM's for longer period of times, with utilize a 2 Pole configuration. On the other hand, a 4 pole configuration spins a set of magnets with 4 poles. Thus, in order to generate AC power at the same frequency (60Hz), the 4 Pole generator need only spin at half the speed of the 2 Pole generator, or 1800 RPM.

Q: What is the difference between 1 and 3 phase power?

A: 1 phase power is probably the type of AC power you are familiar with. It is power delivered in a single sine wave. The downside of single phase power is that the sine wave crosses 0 Volts 120 times every second. While this doesn't present a problem in a residential setting, most commercial and industrial setting require a more steady form of power. Three phase power uses three sine waves, separated by 120°, to deliver near-peak power at any given moment in time.

Please be safe. Hire a professional.