What Are the NFPA 70E HRC Hazard Risk Categories of OSHA?

Electricity is one of the most pervasive and helpful natural forces harnessed for use in our daily lives. However, by its very nature, it poses significant hazards to the human body. If not tended to properly and safely, electricity can cause severe injuries and fatalities. This risk is especially present for the hardworking men and women who maintain electrical infrastructure, machinery, and processes in a variety of today’s modern industries. Electrical engineers, electricians, technicians, operators, and maintenance workers may all be subjected to potential dangers when working in certain environments. It is imperative that they remain qualified and are well educated to help recognize any hazards, and avoid them.

To help business owners recognize these possible hazards and create a safe work environment for their employees, both federal and state regulatory systems have been put in place to help mitigate risk. Founded in 1970, the Occupational Safety and Health Administration, or OSHA, has been critical in the enforcement and education of safe and healthy work practices.

The Occupational Safety and Health Administration, along with several other federal, state, and local regulatory agencies are responsible for setting the common guidelines employers must follow. Failure to meet these regulatory guidelines can result in heavy fines, and it can create a potentially unsafe environment for your employees.

There are several federal codes that are designed to meet safety standards for electrical utilities and other industry applications that demand the use of high voltages. These standards include those found in the Code of Federal Regulations, the National Fire Protection Association, or NFPA, as well as the National Electric Code. OSHA is responsible for inspecting businesses and enforcing these strict standards to help ensure worker safety is universal across the nation.

To make sure the standards are comprehensive and address many of the numerous potential hazards, many of OSHA’s guidelines draw on other codes and regulations set forth by other agencies, including the National Fire Protection Association. NFPA hazard risk categories are often used to assess dangers for electrical workers as well as other employees who may be exposed to the hazards presented.

Electricity can cause electric shocks, burns, fires, and even explosions in some cases, making it both a hazard to human health as well as a fire hazard. In 2007, nearly over 200 employees died as a result of exposure to an electric current. Many others have been severely injured as a result.

In 2007 over 200 employees died from exposure to an electrical current

This includes injuries sustained from electrical fires and explosions. The human body operates on electricity, but it also serves as a conductor, making it potentially lethal if a person comes in contact with an electrical current. Even a current with levels as low as three milliamperes can cause injuries and involuntary muscle reactions from an electric shock.

In some cases, burns may be a result of the improper personal protective equipment or clothing. For fire risks resulting from electricity, the National Fire Protection Association has created a hazard risk category, or HRC, to help employers better recognize potential dangers for their employees. The NFPA’s HRC guidelines also fall in line with the Occupational Safety and Health Administration’s enforcement measures. In this guide, we will take a brief look at the different category levels and what hazards they are designed to protect against.

Having well trained and educated employees who are qualified to recognize and avoid these risks is also imperative to maintaining health and safety at your business. Please take a look at the NFPA 70E Hazard Risk Categories to get a better understanding of what you and your employees should look out for.

What Is National Fire Protection Association 70E?

The National Electric Code and Occupation Safety and Health Administration draw from the National Fire Protection Association for many of their workplace electrical safety standards. The NFPA created 70E, which is the nationally recognized standard for electrical safety used across the United States. It is a document comprising many guidelines and practices and was first adopted in 1976. Since then, the standards have been revised and amended several times to accommodate advances in electrical safety and technology.

NFPA 70E is, and has been, the basis for all enforced electrical worker safety standards on a federal level for many years. Understanding its guidelines is essential to both businesses and employees because it is used across the board for numerous industries, professions, and training programs.

What Are NFPA Hazard Risk Categories

Categories for the NFPA 70E requirements are assigned a designated level ranging from zero to four, which is the highest level risk. Each category for the standards assigns different levels of personal protective equipment for the worker and the proper requirements for working on any type of energized equipment.

Anyone who is going to be working with electricity must be informed, educated, and trained of the NFPA 70 E categories as they are also used by OSHA and the National Electric Code. This includes proper labeling and warnings that need to be placed on panels, controls, and other spaces designed to notify employees that hazards are present. OSHA acts as the enforcement agency and can issue citations and even heavy fines for employers who do not meet the standards. The NFPA 70E was adopted by OSHA, and if you are in compliance, you will meet the acceptable standards required by the administration.

The category levels of hazard risk are based on the calories — or units of heat — per square centimeter in a workspace. A calorie is defined as the amount of energy that’s needed to raise the temperature of a single water gram one degree Celsius at one atmospheric pressure. A second-degree burn can occur from 1.2 calories per square centimeter per second.

Your body uses food, which is broken down to supply your organs with the energy needed to move and function. The number of calories per centimeters squared are used to designate the potential hazard category and the level of personal protective equipment, or PPE, a worker must have available. Improper PPE measures can result in second- and third-degree burns, depending on the hazard risk level. Each category uses a minimum arc rating of personal protective equipment based on calories per centimeters squared.

NFPA 70E Hazard Risk Categories, or HRC, PPE requirements

Here’s a breakdown of the HRC categories and the PPE requirements for each:

HRC Categories - HRC0, HRC1, HRC2, HRC3, HRC4

    • HRC 0 – With a minimum arc rating of personal protective equipment at zero, regular undergarments made from cotton, long-sleeved shirts, pants, hearing protection, safety goggles, and insulated gloves are the needed personal protective equipment required for this category. Only one layer is required to meet the standards.


    • HRC 1 – Again only one layer of protection is needed with an arc rating of PPE ranging to four calories per square centimeter. Cotton undergarments can be worn, but appropriately arc-rated shirts with long sleeves are also needed, as are pants, hard hats, face shielding, hearing protection, leather shoes, insulated gloves with protection, and flame-resistant coveralls.


    • HRC 2 – As arc rating of PPE rises to eight calories per square centimeter, one to two layers of PPE will be needed to meet the standards. At category 2, additional flame-resistant equipment in needed. Cotton undergarments can still be worn, but 12 calorie arc-rated flash hoods, hard hats, and face shields are needed along with coveralls, jackets, and bibs for safe working. In addition, protective gloves with insulation are needed.


    • HRC 3 – At 25 calories per square centimeter for an arc rating, the PPE requirements for previous categories, such as safety goggles, leathers shoes, and insulated gloves are necessary. However, additional PPE components are needed as well, such as short-sleeve natural fiber shirts along with flame-resistant clothing. Three to four layers of PPE is also necessary for HRC 3. It is imperative that workers have 25 calorie arc-rated hoods, coveralls, jackets and bibs, as well as 50″ coats with leggings, which are all required to meet OSHA’s standards.


  • HRC 4 – This is the highest risk category on the list, with calories per square centimeter at 40 for its arc rating of PPE. As with the above mentioned categories, leather shoes, insulated gloves, and safety goggles are all needed. In addition, all arc-rated hoods, coveralls, jackets, and bibs must be 40 cal arc rated. Four layers of PPE is required for working in these high risk levels. An arc flash suit must be rated properly to meet this requirement as it poses the most severe and highest risk to a worker.

What Are Some of the Basic Electrical Hazards?

Now that you have a better understanding of the different hazard risk category levels set forth by NFPA 70E guidelines used by OSHA, you can take a look at some of the common hazards and why they demand certain levels of personal protective equipment.

Arc flashes, or arc blasts, are a form of electrical explosions that can occur. They are often a result of an electrical short. Arc flashes can occur almost anywhere, and they expose workers to high and severe risks during routine practices like maintenance. For example, arc flashes can vaporize metal conductors and explode with plasma bursts and molten metal. Most arc flashes are not this severe, but some explosions can be lethal, causing both fire and injuries to workers and nearby personnel. Arc ratings on PPE are designed based on the probability of both second- and third-degree burns. These pieces of equipment are usually assessed by their total arc thermal performance level, or the amount of heat a flame resistant material can be subjected to until a burn occurs.

Under the NFPA 70E documentation, incident energy is used to describe these types of arc flash hazards. It is the amount, or level, of incident energy determined by calories per centimeter squared. This includes the amount of heat that an electrical arc creates. As mentioned earlier, only 1.2 calories per centimeter squared is enough to induce second-degree burns. Any arc flash levels exceeding 40 calories can be fatal. Fortunately, clothing and equipment capable of withstanding up to 100 calories per centimeter squared is available. However, while it is capable of handling the heat, it is not designed to withstand the force and pressures generated from a blast.

Another hazard to consider is lower fault currents. Fault current levels can determine the arc flash hazard present on a piece of equipment. Engineers can measure fault current levels on distribution systems and devices. Lower fault current levels and longer circuits can increase the severity of incident energy levels.

These are just a few of the hazards to consider when looking at HRC levels. Other standards set by agencies like OSHA and the NFPA require the proper warning labels to be placed on hazard areas and work spaces for employees. It is important that employees are educated about proper procedures, what hazards are present, what type of personal protective equipment is needed, and how to avoid the dangers around them while working.

How to Better Understand NFPA 70E to Meet the OSHA Requirements

When it comes to the many and varied federal, state, and local regulations that need to be met, business owners and managers might feel overwhelmed. There are a wide variety of options available for both you and your employees to better understand how to comply with OSHA’s guidelines. The occupational safety and health administration has numerous online resources available.

The occupational safety and health administration has numerous resources available online

In addition, OSHA often directly supplies employers with training materials, guideline documentation, and reports for particular areas that are not in compliance. However, not meeting OSHA requirements, even if you were unaware, can still result in heavy fines. After a citation is issued, if the problem is ignored, even heavier fines might be levied against your business as it could be seen as willful.

For some employers, setting up an internal training program, ongoing education and inspections might be a better way to maintain worker safety and ensure compliance with OSHA standards. In some cases, employers may not have the resources or man power to invest in maintaining a program of that scale. Supplying employees with protective equipment is not enough to maintain worker safety. Workers must also be knowledgeable, skilled, and aware of the hazards they face on the job.

Employees can benefit from training programs designed specifically to meet the jobs demands, how to identify hazards, and how to avoid them. Customized training programs can help fill in the gaps from the overarching guidelines and requirements supplied to employers by OSHA.

Qualified electrical workers are the only ones permitted to work in high-risk areas under NFPA 70E and OSHA regulations. They must be able to supply documentation indicating they meet the requirements of the job and can handle working in high-risk category situations. At Technical Skills Development Services, we offer employers a way to customize their training and design hazard-specific training designed to meet all of OSHA’s requirements.

Contact us today for more detailed and comprehensive information on our services

Please contact us today for more detailed and comprehensive information on our services. We can ensure your business and workers are trained to meet all of the legal requirements OSHA sets forth.