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NFPA 70E is a national consensus standard that establishes “best practices” for protection from electric arcs.

Employers must conduct both shock and flash hazard analysis to establish a flash protection boundary.

If live parts operating at 50 volts or more are not placed in an electrically safe work condition, written authorization by an energized electrical work permit is required.

The employer is responsible for the safety and training of employees. Employees must be qualified to do the work and trained to understand the specific hazards and potential injury associated with electrical energy.

Flame resistant clothing and personal protective equipment (PPE) must be worn based on the incident energy associated with the specific task as determined by:

Flash hazard analysis

Review of the requirements for the task from the PPE Matrix (in the NFPA 70E Update Table 130.7(C)(9)(a), OR

Using the simplified approach to select appropriate clothing based on whether the task requires “everyday work clothing” or “electrical switching clothing” (in the NFPA 70E Update Annex H)

Three Steps to Compliance with NFPA 70E:

1. Conduct both shock and flash hazard analysis to determine incident energy potential within the flash protection boundary.

Employers are required to conduct a hazard analysis to determine the “flash protection boundary.” Inside the flash protective boundary, exposure to an electric arc is predicted to cause a second-degree burn injury and PPE is required. Required FR clothing and other PPE is based on the specific hazard present.

The severity of the arc hazard is defined as incident energy in calories per centimeter squared (cal/cm2). It may be determined by three methods.

Method A estimates the incident energy based on knowledge of the electrical systems and work practices; Method B estimates the incident energy by determining hazard risk category classifications from tables of common work tasks; Finally, Method C lays out a simplified two-category FR clothing system that provides two PPE clothing categories, “everyday work clothing” and “electrical switching” clothing, to assure

2. Determine PPE required based on incident energy associated with the specific task.

The NFPA has identified four FR hazardous risk category levels, which are numbered by severity from 1 to 4. Hazard Risk Category is the level of arc flash protection clothing you must wear to protect against a minimum level of incident energy measured in calories per centimeter sqared. Meaning, electrical equipment, depending upon the energy delivering capability, under fault conditions can cause an explosion, or arc fault of a certain level, again measured in calories per centimeter squared.

The chart, based on specific job tasks, ranges from HRC 1 (which is low risk and allows for 100% treated cotton), up to HRC 4 (which is high risk and requires FR clothing with a minimum arc rating of 40). The HRC is used to determine the necessary arc rating of a garment worn during a given job task. Wearing multiple layers of clothing may be required to obtain the necessary rating required for your job.

Clothing Description
(Typical number of clothing layers is given in parentheses)
Required Minimum
Arc Rating of PPE

FR shirt and FR pants or FR coveralls (1 layer)

Cotton underwear plus FR shirt and FR pants (1 or 2 layers)

Cotton underwear plus FR shirt and FR pants plus FR coveralls, or Cotton underwear plus two FR coveralls (2 or 3 layers)

Cotton underwear plus FR shirt and FR pants plus multilayer flash suit (3 or more layers)


3. Select PPE matching the hazard to the arc rating of the garments.

Garments are rated based on their ability to protect against electric arcs. This arc rating is expressed in cal/cm2. The standard requires that garments have a minimum arc rating, which may be either ATPV or EBT.

Be aware that other PPE may be required for specific tasks including double-layer FR flash hoods, FR hard hat liners, safety glasses or safety goggles, hard hat, hearing protection, leather gloves, voltage-rated gloves, and voltage-rated tools.

The most prudent course for any company faced with an ignition hazard is to select protective clothing made from flame resistant fabrics. Untreated cotton and wool are not flame resistant and fabrics made from these fibers do not make adequate protective clothing for the range of hazardous conditions encountered in industry.


For More Information Visit One of the Following Websites

NFPA - National Fire Protection Association

IEEE - Institute of Electrical and Electronics Engineers

EEI - Edison Electic Institute

NSC - National Safety Council

OSHA - Occupational Safety and Health Administration

ASTM - American Society of Testing and Materials

Westex Inc. - Flame Resistant Fabric Manufacturer

Bulwark - Priemer Flame Resistant Clothing Manufacturer

See these pages for additional information: