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Commercial Generator Buyer's Guide


Imagine this: Severe weather in your area knocks out power to thousands in your city. Are any of these thousands your competitors? If the power goes out, can your business afford to wait for the power to come back on?

Are you in the food service industry and risk losing a ton of money in perishable food every time there is a blackout? Or does your medical institution operate life-saving equipment that must continue running 24-hours-a-day? No matter what your industry, you probably use computers to keep up with competition, inventory and customers. If you have a website, you use them even more. How far behind your competition would your business be if you were without power for three, or even one day? Would you lose all sorts of important data?

Nowadays, owners of all sized businesses are protecting their company with a backup commercial generator. In the event of a utility power outage, a generator restores power to your business, whether you are on-site or not, and your company continues business as usual.

Why Does My Business Need a Commercial Generator?

These days, due to extreme weather, construction, and other unanticipated complications, extensive power outages can mean real problems for day-to-day business.

These days, power is essential to any business, small or large, and damage can be great if you lose power for days, or even only hours. Having backup power means that you will be able to stay in business no matter what happens.

When you have a backup generator, in the event of a power outage (either because of extreme weather, rolling blackouts, or malfunctions in the power grid) the automatic transfer switch (which is installed along with the generator) recognizes that you are no longer receiving power from your utility lines, and within seconds, it switches the generator on as your power source, and voila! You are back in business, literally!

Today’s standby power generators are fully automatic, self-contained, and built to be permanently installed outside your business, either at ground level or on the roof, just like an air conditioning unit. You almost wouldn’t know it was there, until you needed it. You can elect to backup selected emergency circuits only, or your entire facility.

Understanding Commercial Generator Basics

If you are thinking that a power generator is a complicated piece of equipment that you could never understand, here is a simple breakdown of their parts. Four important components of a generator are:

The engine (also called the motor) of the generator burns fuel—usually propane, natural gas, gasoline, or diesel—to supply power.

The generator head then turns that power into electricity.

Most commercial generators require a transfer switch, which acts as the interchange between utility power and generator power. The switch recognizes an absence of utility power, and switches your electrical circuits to the generator as their power source. This process happens in roughly 30 seconds or less. As soon as utility power comes back on, the process is simply reversed.

The size of a generator is measured by the amount of wattage it produces, in kilowatts (kW). Sizes range from 1 kW for the smallest, gasoline-powered, portable generators, to hundreds of kW’s for large, industrial generators. The typical range for a commercial generator is 2kW – 20kW for small to medium-sized businesses, and 20kW – 250-plus kW for industrial-sized businesses.

There are several other features of commercial generators that you might be wondering about.

Single-phase and Three-phase Generators . A generator produces either single or three phase emergency power. Choose a single phase set if you do not have any motors above five horsepower. Three-phase power is better for motor starting and running. Most small businesses will require a single phase generator, whereas medium to large businesses and industrial applications usually require three phase power.

Generator Cooling Systems.

Air-cooled generators cost less than liquid-cooled generators, but produce more noise and are less efficient. Portable generators are almost always air-cooled.

Liquid-cooled generators typically cost more to purchase and maintain. Standby generators 20kW and larger typically use quiet, dependable, and effective liquid cooled systems.

Types of Commercial Generators

There are two types of generators that can be used as a power source for your business.

Standby Generators are installed permanently as an emergency, backup power source. They are hardwired into your business’ electrical system and can be fueled by city gas or propane lines. Installed outside of your business, they resemble an air conditioning unit. Commercial standby power used to be costly for businesses, but now it is possible to have reliable and affordable standby power. These are wise investments for areas that may experience frequent power outages.

Portable Generators are gas or diesel-powered devices which provide temporary electrical power. They have a fuel tank, and standard power outlets that can plug into ordinary extension cords. They can be useful in remote locations that don’t have power available, to plug in tools and lights. There is a secondary class of portable generators, called towable generators. These larger, industrial-sized portable generators are tough and rugged, and are more appropriate for construction sites, mobile telecommunications and utilities businesses, and lifesaving fire and emergency situations. They are mounted on a trailer so they can be towed to your worksite

Is Diesel, Natural Gas or Gasoline Best?

There are several different fuel choices for commercial generators. Fuel availability in your area, shelf life, and other factors will help in your decision for which type of commercial generator is best for your business.

Propane/Natural Gas

Pros: For standby generators, they can be hooked directly into your gas utility lines (no fuel storage necessary), they are clean burning, and quiet running.

Cons: Lower output (may need larger generator compared to diesel)


Pros: The diesel generator is the most fuel-efficient. A gallon of diesel fuel will last 2 to 3 times longer than gasoline. Diesel generators are designed to run continuously for hours, are very durable and dependable.For this reason they are the most common choice for commercial generators.

Cons: Diesel generators are noisier, require delivery and storage of diesel fuel, and they are usually the most expensive, which makes them common for larger, commercial/industrial applications.


Gasoline generators are smaller, and not commonly used in commercial situations. They are more common for recreational (camping) and short residential uses.

How Do I Choose the Right Size Commercial Generator?

The most important factors in figuring out which type generator is best for your business are where it will be used and what it will be used for. Does it need to be able to be moved? Asking yourself these questions will help narrow down your options. The next most important factor is sizing your generator. Too few watts and you risk overheating the generator and ruining anything hooked up to it, and too many watts will cost more money than you need to spend.

Determining Wattage Requirements. You will need to decide what equipment and/or machinery you will want the generator to power. You will also need the startup requirements for each piece of equipment, as machinery that has a motor or compressor (like an air conditioning unit), requires more power to start up than they do to continue running (as much as three times more).The most accurate way to do this is have an electrician do the measuring for you. This way you can be sure it’s done right, and more importantly, done safely.

What Size Generator to Buy. Once you (or your electrician) have figured out the requirements for your desired machinery and equipment, you’ll know what size generator to look at. It’s a good idea to add about 20% to your number to avoid overloading your generator and give you room to add to its load in the future.

New vs. Used Generators

The benefits of buying a new generator are just that; it is brand new and will have a warranty. But to save your business some money, a used commercial generator can be money well-spent. A diesel generator can run up to 15,000 – 30,000 hours, so if you buy a used generator from a reputable vendor who sells well-maintained machines, you can easily get several years of use from it.

Some things to consider when purchasing a pre-owned generator:

  • Age, hours, and usage
  • How well it has been maintained
  • Does it come with a limited warranty?
  • Physical wear and tear on the unit

Commercial Generator Installation

If you’ve decided that a standby commercial generator will suit the needs of your business, you’re probably curious about the installation process. Usually, a dealer will come to your business and evaluate what it will take to install the system and to determine specific generator needs.

Professional Installation. Because a standby generator is wired into your business’ electrical system, correct installation is crucial. To connect a standby generator to the electrical system, a separate apparatus called an automatic transfer switch will also need to be installed. The transfer switch is what “switches” your power source from the power grid to the generator and back. A professional electrician must install the transfer switch.

For portable generators, there is no installation process. You will just need to decide where you will store it and its fuel. If it will only be used for backup, you might want to store it somewhere that is easy to access when the power goes out. Remember that this might happen during inclement weather.

Questions I Should Ask a Commercial Generator Dealer

Maintenance and service are especially important, so you’ll want a generator dealer who services your area. The great thing about 360Generators is that we will only send you quotes from companies that service your area.

Some questions you should ask the dealer:

  • What maintenance services they’ll provide (standby generators require an annual checkup of oil levels, air flow, and other factors, at minimum)
  • What are the operating costs of the different types of generators?
  • How long is the installation process?
  • What equipment can I run?
  • Do I need a transfer switch?

How Do I Find a Reliable Commercial Generator Vendor?

The best way to find a vendor and to get a good deal on a commercial generator is to shop around as much as possible, and compare. Using our service makes that process easy, because not only do you not have to do the legwork, but you will have up to five qualified, reputable vendors to choose from! Fill out our simple commercial generator form, and the right vendors will call you, and then you decide which is best!

How Much Will a Commercial Generator Cost?

As a loose rule of thumb, standby generators cost $300 to $500 per kW, installed. Smaller portable generators are less expensive, ranging in the hundreds-of-dollars to the low thousands. Larger industrial generators can run anywhere from a couple thousand dollars to ten- or twenty-thousand dollars, and higher. Purchasing a used generator can save you as much as 25% - 50% off the initial cost.

Other Tips & Frequently Asked Questions

Don't Max Out. The level of power a generator can deliver on a continuous basis is its “rated capacity”. It is usually about 90% of its maximum power. An electric generator can run its maximum capacity for no longer than 30 minutes before beginning to overheat. When you are tallying up your wattage requirements, keep this in mind.

Expect it to Exercise Regularly. To make sure they are up to par when they are actually needed, standby power generators will automatically perform regular monthly or weekly test exercises. Many models have a quiet function for the exercise “sessions.”

Should I Inform the Utility Company That I Have a Generator? Yes. Most utilities keep this sort of information and make it available to the line workers that will be servicing the area. Having this information can reduce setbacks to power restoration.

Accessorize! Althoughmost generators come equipped with an industrial grade muffler, a good investment is a residential or critical muffler. They are much quieter and last longer. It is also a good idea to ask about enclosures for your generator; they also help with noise reduction and protect it from the elements.

I'm Ready to Purchase a Commercial Generator...Where Do I Shop?

The easiest and most effective way to shop is to have generator dealers compete for your business. The more you shop around, the higher your chances of getting exactly what you want, at the right price. Here at 360Generators, we take the hassle out of the process, providing you with estimates from a variety of dealers so you can make the best choice for your business needs. All you have to do is fill out our simple commercial generator form, and up to five qualified dealers will contact you with their offers!

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