How Long Can a Generac Generator Run Continuously?

Ian Mutuli
Updated on
Ian Mutuli

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.
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With all the accolades it has won over the years, it is hard not to come by Generac whenever you are in search of a good generator. It has a vast array of generators that will be perfect for any occasion, but only if you know which one is ideal for you.

On the other hand, if you are just learning about Generac generators, the first question that pops into your mind is usually about how long these generators can run continuously. While giving a figure like 8-100 hours is easy, there are different factors that can either make Generac generators run continuously for longer or shorter periods.

This article thus takes a look at some of the different factors that will affect how long your Generac generator can run continuously.

For starters, Generac ideally deals with two kinds of generators. These are the standby and portable generators.

Portable Generators

As their name suggests, portable generators are intended to be hassle-free in that you can easily move them from one location to the other. They are also relatively cheap as some of Generac's cheapest portable generator models start from $430. It is also possible to find more expensive but powerful models like the XD5000E which costs well over $3500.

Assuming you've hooked up a 50% load, you can expect Generac's portable generators to give you about 10 hours of continuous and stable power supply on a full tank. The narrative is a little different if you went for the more powerful models since at 50% load, you can get up to 30 hours of continuous run time.

While the higher-end Generac generators have longer run-times than the more affordable Generac generators like the GP3300, you should know that their fuel tank capacities differ. As such, high-end Generac generators have larger fuel tanks, and this is the main reason why they last longer.

Standby Generators

Hospitals and business premises are some of the different institutions that would greatly benefit from standby generators. This is because they have an automatic transfer switch which will ensure you get zero power interruptions whenever the mains power goes out.

Generac has plenty of such standby generators that are ideal for a variety of uses. If you intend to install a standby generator in your home, then perhaps Generac's home backup generators may come in handy.

Generac 20kw Generator For Emergency Power Outages

Typically, standby generators cost a decent amount of money that can range anywhere from $2,000 to $30,000. This is indicative of the kind of service you can expect from these generators as well. Diesel powered Generac generators like the Protector Diesel generators can have continuous run times of up to 90 hours which is well over 3 days!

Type of Fuel

Excited about the run times of Generac's standby and portable generators? Well, that will depend on the kind of fuel that the generator will be consuming. Once again, Generac offers a variety of generators to choose from depending on the type of fuel that is readily available in your location. The three main types of fuels that these generators run on include:

  • Natural gas
  • Diesel
  • Liquid propane

Natural Gas

You're in luck if your home is hooked up to a natural gas supply by your utility company. This is because you can comfortably pick a Generac generator that runs on natural gas. In addition, you may end up paying less compared to someone who opted to go for a diesel-powered generator.

Most Generac generators that run on natural gas also happen to be standby generators. Installation of such generators will probably cost a few extra bucks, but you will get amazing run times from these generators because you will always have a constant supply of fuel.

Generac's PowerPact Home Backup generator is a good example of a standby generator that has an amazingly long run time. Apart from the occasional maintenance check ups that you will have to conduct on the generator, your only worry when dealing with Generac's natural gas generators would only be if your natural gas supply was cut.


More often than not, these are the most robust kinds of generators that Generac has. In fact, many standby and portable generators from Generac use diesel because it is a popular type of fuel worldwide.

If you are interested in one of Generac's Home Backup generators that runs on diesel, you should first know that you can buy them with extended tanks which will enable you to store more reserve fuel. 

The 30KW and 50KW Generac Protector Diesel series generators, for example, can be paired with a 132-gallon tank while the smaller 15KW and 20KW models can use the 95-gallon tank. Supposing you went for these extended tanks, you can expect run times of not less than 25 hours at 50% load. However, it is possible to still get over 100 hours of run time from these generators. 

While 100 hours of run time sounds exciting, the cost of running the generator for such long hours may not be as exciting especially when you factor in the cost of fuel. Regardless, diesel-powered Generac generators are the way to go if other types of fuel are not readily available in your locality.

Liquid Propane

If you don't fancy natural gas or diesel, your only remaining option is liquid propane. In most cases though, you will find that if you settle for a Generac generator that runs on liquid propane, it could very well run on natural gas too.

Whether you prefer a standby generator or a portable generator, you are sure to find a Generac generator that runs on liquid propane. The Generac 6000 LP3250 is a good example of a propane-powered portable generator.

Compared to generators that are powered by either natural gas or diesel, the run times of propane-powered Generac generators are limited to the capacity of the liquid propane cylinders. In addition, there is also the risk of running out of liquid propane when the demand for power goes up. This is why most Generac generators that run on liquid propane also use natural gas.

Liquid propane is not necessarily cheaper than natural gas. However, since it can be easily stored in cylinders, it becomes a viable option for those people who are in remote locations or where access to natural gas is somewhat limited.

Important Considerations

Whereas we only looked at the two main factors that will determine how long your Generac generator can run continuously, there are usually a few more factors that depend on your usage. 

In addition, even though your Generac generator can run continuously for days, it is generally recommended to use the generator as a power backup and not as a day-to-day power source as running a generator for long can eventually become expensive.

With that said, here are some of the considerations you need to make if you intend to run your generators for lengthy periods.

Regularly Replace the Generator's Engine Oil 

Just like your car, a Generac generator requires oil which is essential in lubricating the engine and keeping it cool. A generator that is not oiled will often overheat and lead to faster wearing and tearing before it starts to develop other mechanical complications.

For this reason, ensure you give your generator a break once in a while and oil it first before powering it on again. Most manufacturers recommend that you change the oil after 200 hours of operation. You can find detailed information on when to change the oil of your Generac generator by reviewing the generator's spec sheet.

Have a Reliable and Consistent Fuel Source

This may seem obvious and straightforward, but you may not get even half the run time if you run out of fuel. As such, you should always strive to stock up a few extra jerricans of fuel or cylinders of liquid propane so that you never have to deal with a low fuel warning.

By default, if you did proper sizing when picking a Generac generator, you should know exactly what amount of fuel you require and how long it can last you. This will be helpful as it can guide you on when you need to go for refills.

Don’t Run the Generator in Enclosed Spaces

The longer you run the generator, the more carbon monoxide the generator will produce. If you placed the generator in an enclosed space, you will be risking carbon monoxide poisoning. In addition, the generator won't be running as efficiently as it should be and will thus have shorter run times.


Summing it all up, there is a lot to expect from Generac generators when it comes to continuous run time, but that will often depend on the type of generator you choose. Generac generators that run on natural gas, for instance, will have the longest run times. However, having a steady supply of natural gas will be important. The same applies to other Generac generators that use different types of fuel.

Ian Mutuli

About the author

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.
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