Arc Flash Program: Incident Energy Studies, Equipment Labeling, and NFPA 70E Compliance

Most facilities with arc-rated PPE in the stockroom don’t have an arc flash program. They have PPE. Those are different things. An arc flash program tells you how much energy could hit a worker at a specific piece of equipment, what PPE is actually required at that equipment, when workers can work energized at all, and what the permit process looks like. Without the study data behind it, a cabinet full of arc-rated gear is just a guess.

NFPA 70E is the standard that governs electrical safety in the workplace, and OSHA’s electrical standards at 1910.331 through 1910.335 reference its requirements. A real arc flash program starts with an incident energy analysis and uses that data to drive every other decision.

What an Arc Flash Program Actually Is

An arc flash program is a documented system that covers hazard analysis, equipment labeling, PPE selection, energized work permits, training, and maintenance requirements. The study tells you the hazard. The program tells everyone what to do about it.

The hazard analysis is the foundation. Without it, you can’t complete accurate labels, you can’t select appropriate PPE, and you can’t defend your energized work decisions if someone gets hurt.

A lot of facilities skip the study because it costs money and takes time. Some use the “table method” from NFPA 70E as a shortcut, which assigns PPE categories to equipment based on general parameters. The table method is allowed under NFPA 70E, but it has real limits. It can overestimate or underestimate the hazard significantly depending on your system configuration. If your incident energy at a given switchboard is 68 cal/cm², the table method won’t tell you that, and PPE Category 4 is only rated to 40 cal/cm². The study method is the safer approach for medium and high-voltage equipment, large transformer banks, and anywhere system configuration deviates from typical.

The IEEE 1584 Incident Energy Study

IEEE 1584 is the engineering standard that defines how to calculate arc flash incident energy. The methodology uses your system’s available fault current, the arc duration based on how fast your protective devices clear a fault, the working distance, and equipment geometry to produce a cal/cm² value.

To get the study done, your engineer needs your electrical one-line diagram, your short circuit study, your protective device coordination study, and transformer nameplate data including impedances. If those documents are outdated or missing, they’ll need to be developed first. That’s the more common situation than most safety managers expect.

The engineer models your system in software, typically SKM Power Tools, EasyPower, or ETAP, and runs the calculations at each piece of equipment. Output includes the incident energy at the working distance, the arc flash boundary, and the recommended PPE. The results are equipment-specific. The switchgear at your main distribution point and the panelboard down the hall can have dramatically different incident energy values.

Licensed electrical engineers or specialized electrical safety consultants perform this work. The facility is responsible for keeping the study current after it’s delivered. The original engineer isn’t on the hook for changes you make to the system after the study date.

Equipment Labeling Requirements

NFPA 70E 130.5(H) requires electrical equipment to be field-marked with arc flash labels. The label has to include the nominal system voltage, the arc flash boundary, and enough information to select appropriate PPE.

That means at minimum one of these: the available incident energy and corresponding working distance, the arc flash PPE category, the minimum arc rating of required PPE, or the site-specific PPE level. Most study-based labeling includes the incident energy, working distance, PPE minimum arc rating, arc flash boundary, and available fault current. That information gives a worker everything needed to assess the task.

Pre-printed generic labels, the kind sold in bulk that say “Danger: Arc Flash Hazard, Wear PPE,” don’t satisfy 130.5(H). They don’t include site-specific data. OSHA inspectors and NFPA 70E auditors flag these consistently.

Labels have to be updated when the electrical system changes in ways that affect incident energy. That’s not optional. A new transformer, a breaker replacement with different clearing time characteristics, or a system reconfiguration can all change the numbers significantly.

Using Study Results to Select PPE

The incident energy at the working distance drives your PPE arc rating requirement. If the study says 12 cal/cm² at 18 inches on a piece of equipment, the arc-rated PPE worn by someone working at that equipment needs a minimum arc rating of at least 12 cal/cm².

Arc rating is expressed as either an arc thermal performance value (ATPV) or an energy breakopen threshold (EBT), whichever is lower for multi-layer systems. The arc rating on the garment label has to meet or exceed the incident energy value from the study.

The layered system matters. An arc-rated shirt rated at 8 cal/cm² worn under an arc-rated jacket rated at 14 cal/cm² does not combine to give you 22 cal/cm². Layered arc-rated systems have a combined arc rating that has to be tested as a system. Don’t add arc ratings. Use tested system ratings.

NFPA 70E’s PPE categories (1 through 4) are an alternative approach when the table method is used instead of an incident energy analysis. Category 1 requires 4 cal/cm² minimum. Category 4 requires 40 cal/cm² minimum. If your study produces values above 40 cal/cm², you’re outside the table method entirely and the incident energy method must be used.

See the PPE guide for documentation and inspection requirements for arc-rated clothing.

Energized Work Permits

The default under NFPA 70E is to de-energize equipment before working on it. Energized work is the exception, and it requires justification.

An energized electrical work permit is required when workers will perform tasks on or near exposed energized conductors or circuit parts that haven’t been placed in an electrically safe work condition. The permit documents why the work must be done energized, what the hazards are, what PPE is required, what the boundaries are, and who has authorized the work.

NFPA 70E 130.2(B) lists the specific information a permit must include: a description of the circuit and equipment, the justification for why the work must be performed energized, a description of the safe work practices employed, the results of the shock risk assessment, the results of the arc flash risk assessment, the PPE required, a means of communication, people in attendance, and the person authorizing the work.

Energized work permits don’t replace lockout/tagout. They apply to a different situation where LOTO isn’t practicable and energized work has been properly justified and controlled. If LOTO is possible, LOTO is required.

Equipment Maintenance and Incident Energy

This connection gets missed in a lot of programs. Circuit breakers that don’t operate at their rated interrupting time dramatically increase arc flash incident energy.

A breaker that’s supposed to clear a fault in 3 cycles but has never been tested or maintained may actually take 10 cycles or fail to trip entirely. The difference between 3-cycle clearing time and 6-cycle clearing time can double the incident energy at a given piece of equipment. Your study assumes devices operate as designed.

NFPA 70E and NFPA 70B both require electrical equipment maintenance as part of a safe electrical work program. When was your main distribution switchgear last tested? When were your medium-voltage breakers last exercised and timed? If the answer is “I don’t know,” your study results may be optimistic.

Annual infrared thermography, periodic breaker testing, and documentation of all maintenance activity are part of a defensible arc flash program.

Training Requirements

NFPA 70E requires training for qualified electrical workers on the specific hazards associated with their work, including arc flash. Training has to be provided before workers perform tasks on or near exposed energized conductors, and it has to be repeated every three years at minimum, or more frequently if safety-related work practices, equipment, or operations change.

The NFPA 70E certification is the credential that validates this training. It’s not required by OSHA, but it’s the recognized benchmark for demonstrating worker qualification. The electrical safe work practices guide covers what qualified worker status means in practice and what distinguishes qualified from unqualified workers for specific tasks.

Training documentation needs to identify who was trained, when, on what content, and by whom. Verbal training without records doesn’t satisfy NFPA 70E’s documentation expectations.

Program Maintenance and Update Triggers

An arc flash program is a living document, not a one-time project. NFPA 70E requires the arc flash hazard analysis to be updated when the electrical system changes in ways that affect incident energy.

Changes that trigger a review: adding or replacing transformers, changing protective device settings, adding large new loads, changing system topology or switching arrangements, or replacing any protective device with a unit that has different clearing characteristics. IEEE 1584 recommends re-evaluating studies every five years even without major system changes, because equipment ages, settings drift, and personnel changes mean configurations may have shifted without formal documentation.

Assign someone responsibility for maintaining the study and tracking system changes. That’s typically the facility’s electrical engineer or a contracted electrical safety consultant on retainer. When the study is updated, labels need to change. When labels change, training may need updating.

The program review cycle should also include a check of whether energized work permits are being used correctly, whether PPE is being inspected and replaced on schedule, and whether near-miss incidents involving electrical hazards have been reported and investigated.

Building this program from scratch is a meaningful project. Start with the one-line diagram. If it doesn’t exist or is out of date, that’s your first task, because the incident energy study can’t happen without it.