NFPA 110 – An Accessible Guide for Emergency & Standby Generator Operators

Standby generators switch on to restore power to your business during an outage, preventing melting freezers or data loss from costing your company thousands or millions of dollars. However, these generators must be installed according to codes set by the National Fire Prevention Association (NFPA) in order to operate safely and efficiently. NFPA 110 stipulates the requirements for operating and maintaining standby generators. It’s a dense and technical text, so this guide will help you understand the basics of it while your generator supplier will handle the rest.  

Who or what is the NFPA?

The National Fire Prevention Association (NFPA) is an independent organization that researches and develops operational recommendations to help reduce fire risks. Since generators rely on combustible fuels and generate electricity, there are plenty of fire risks created by these units. Creating installation and operational codes for certain equipment, such as standby generators, is its primary method of reducing industrial and commercial fires.

What is NFPA 110?

Proper installation according to the NFPA 110 code reduces fire risks and ensures reliable, steady performance through proper sizing for the facility. In facilities where human lives would be at risk due to power loss, such as a hospital, the NFPA 110 is a legally enforceable set of installation requirements. However, the NFPA itself does not enforce these rules. Instead, they are enforced by the local authority having jurisdiction (AHJ) of your area, such as a building code enforcement office.  For less essential uses, the 110 standard is still smart to follow to ensure a reliable and safe backup power system. The standard is currently available in the 2019 edition, and the 2020 edition is not expected for release until after the first quarter of that year.

You can find the latest version of the standard here.

What does the NFPA 110 codes include?

The code includes details on several aspects of generator selection, installation, maintenance and long-term testing. Some of the highlights include:

  • Proper sizing based on generator ratings for the level, class and type of power supply needed
  • Fuel storage requirements based on type to prevent unnecessary fire risks
  • Generator protection against emergency situations that likely triggered the power loss in the first place, such as flooding, fire, and earthquake damage to the structure
  • The installation and use of transfer switches to control which parts of a facility receive power from the backup system
  • Installation of the generator and all related equipment, including equipment to monitor generator activity
  • Long-term maintenance and routine testing requirements to ensure the generator is still operating according to the standard.

The full 2019 edition of the NFPA 110 includes eight distinct chapters and three annexes, so it’s a lot for anyone to read in one sitting. Understanding the basics will help you pick a generator installer who knows the requirements inside and out so you don’t have to memorize them.

Application Classifications

Different businesses have very different power needs when it comes to a power outage. A full-sized hospital may need a tremendous amount of immediate electricity to ensure the uninterrupted operation of ventilation and monitoring equipment, while a small grocery store may just need a small block of coolers to keep running.  Also, melted popsicles or delayed packages simply aren’t as important as hospital patients suffering due to a lack of oxygen or heat.  Naturally, there are varying levels of importance for backup power. These are the reasons why the NFPA 110 standard recognizes different levels, classes, and types of standby generators.


The level of a backup power system is determined based on how essential it is to the facility. Level 1 generators are relied on for human life and safety during a power interruption. If the facility losing power won’t put anyone’s life or safety at risk but could still damage products and equipment, the NFPA considers the system to fall into Level 2.


The class of a generator is set based on the equipment it needs to power, and refers to the length of time a generator needs to run at its rated output without having to refuel. There are dozens of different classes set by the NFPA, so it’s impossible to fully list them all here. Some examples include:

  • Generators that need to run emergency lighting must meet all Class 1.5 requirements included in the standard
  • Emergency power for a facility located near a fault line may need to be Class X, which includes the requirement of being able to run for 96 hours of its full rated output without refueling, or a lower class depending on the distance and risk of seismic activity.

The location of the facility, type of business, and size of the operation can all change the class of generator needed.


Finally, a generator’s type refers to the length of delay it creates when starting. Some high-end systems are considered an uninterrupted power supply because they can kick in within a second or two of lost power and create practically no noticeable outage in essential equipment. Other systems have delays of 10 seconds to no automatic start at all. Obviously essential life-saving equipment will require the uninterrupted type of generator, but other equipment may work just fine with a 10 or 60-second delay before power is restored.

Additional codes that require compliance

While the NFPA 110 covers a lot of details regarding emergency power systems, it’s not the singular body of standards for this situation. Even other standards from the NFPA, such as 1, 37, and 54, apply to most standby generator installations. There are dozens of other potential fire and worker/patient safety regulations that could affect your business depending on the industry, business size, location, and other details. The NFPA 110 standard is a national level code that applies across the country, but each region, state, and county can set their own requirements on top of it. Working with a knowledgeable generator supplier and installer is essential to ensure you meet all the relevant codes and requirements in your area.  Paying to replace or reinstall the generator system after discovering a problem can cost thousands of dollars, so it’s better to do it right the first time by investigating all the requirements relevant to your system.

How to become compliant with NFPA 110?

Even after professional installation according to the standard, an emergency power system must be tested thoroughly to ensure it passes. The generator’s manufacturer or supplier will guide you through this process, which includes a series of short power up tests and then a full-length two hour load test. After you’ve completed the test to the satisfaction of your local authority holding jurisdiction, you’ll receive approval from them to use the system as needed. The NFPA does not require this inspection to be repeated unless the system is modified or replaced, but your local authority may have an annual or biannual inspection program of their own.

With your new understanding of NFPA 110 and what it covers, you’re ready to dive into the document itself. You can find a copy of it available on the NFPA’s website. Your generator manufacturer or supplier will work with you to make sure you meet all of these requirements, so don’t worry too much about understanding or memorizing every rule in the standard.