What Is an Arc Flash Study? NFPA 70E Requirements Explained

Arc flash is one of the most dangerous hazards in an electrical system. In a fraction of a second, a fault can release extreme heat, light, pressure, and molten metal. For facility managers and EHS leaders in semiconductor, life sciences, and industrial manufacturing, a defensible arc flash program protects people and keeps production on track.

An arc flash study is the foundation of an NFPA 70E electrical safety program. It turns real system data into clear labels, safe work boundaries, and PPE guidance. It also helps reliability by revealing coordination gaps and outdated protection settings. Hallam-ICS supports clients with end-to-end services, from studies and labeling to qualified worker training and practical mitigation, so safety practices match real operating conditions.

An arc flash study is an engineered analysis of your electrical distribution system that calculates incident energy at locations where people may work on or near energized parts and defines safe approach boundaries. The results drive equipment labels, PPE selection, and procedures required by NFPA 70E so qualified workers can perform tasks safely and consistently.

What the Study Includes

Field data collection

Engineers verify the system from the utility service to downstream equipment. Typical data includes transformer kVA and impedance, conductor sizes and lengths, protective device types and settings, enclosure details, and grounding method. Reliable field data is essential for accurate results.

One-line diagram development

A current one-line diagram shows how the system is actually configured. If documentation is outdated, it is updated or rebuilt. A validated one-line also speeds troubleshooting, maintenance planning, and future upgrades.

Short-circuit and protective device coordination

Calculations determine available fault current and confirm device duty ratings. Time-current curves and settings are reviewed so upstream and downstream devices operate in the right order. Good coordination can reduce clearing time and lower incident energy, which improves safety and reduces nuisance trips.

If you are modeling complex feeders, our discussion of pad-mounted transformer calculations using SKM and IEEE methods shows how modeling choices affect study outcomes

Arc flash hazard calculations

Using accepted methods, typically IEEE 1584, engineers calculate incident energy (cal/cm²) and determine each location’s arc flash boundary at the stated working distance. IEEE 1584 commonly applies to three-phase AC systems from 208 V to 15 kV and uses inputs such as system voltage, fault current, protective device clearing time, enclosure characteristics, and electrode configuration.

Equipment labeling and documentation

NFPA 70E expects equipment that may be serviced while energized to be field-marked with the nominal system voltage, the arc flash boundary, and either the calculated incident energy with its working distance or a PPE category that is appropriate for the equipment. Labels must be maintained and updated when conditions change.

The final report includes the system model and settings, assumptions, results, and a prioritized mitigation plan that targets the highest risk areas first.

Training and program integration

Study results must be implemented on the floor. Hallam-ICS supports qualified worker training and program updates so labels, boundaries, and PPE guidance are used consistently. For planning blended learning and refreshers, this perspective on whether a learning management system brings value to a safety program can help shape training strategy:
 

Why it Matters in Regulated and High-Hazard Environments

Semiconductor fabs. Uptime and environmental control are critical. Optimized coordination reduces nuisance trips that can disrupt tool availability and cleanroom conditions. When coordinating electrical safety with modernization efforts, see how process control system integration can minimize downtime during upgrades.

FDA-regulated facilities. Documentation and change control are essential. A maintained one-line, labels, device settings, and training records support compliant, auditable programs and align with validation expectations.

Industrial manufacturing with combustible dust. Electrical hazards often coexist with dust, fire, and explosion risks. Aligning your arc flash program with a broader combustible dust safety program using the safety cycle creates a unified, audit-ready approach.
 

What is an Arc Flash Study According to NFPA 70E

NFPA 70E is the consensus standard for protecting workers from electrical hazards. While it does not mandate a single calculation method, it outlines the program elements that an arc flash study supports and ties them to day-to-day safe work practices.

1. Perform an electrical hazard risk assessment

Identify arc flash and shock hazards, estimate likelihood and severity, and define protective measures. The engineered arc flash study provides the incident energy and arc flash boundaries used in this assessment.

2. Label electrical equipment

Field labels must communicate the nominal system voltage, the arc flash boundary, and either incident energy with the working distance or a PPE category for the equipment. Labels must be updated when system conditions change or when new data becomes available.

3. Define approach and arc flash boundaries

Establish limited and restricted approach boundaries for shock hazards and the arc flash boundary for thermal hazards. The arc flash boundary is commonly defined at 1.2 cal/cm² (about 5.0 J/cm²) of incident energy. Your study calculates the arc flash boundary at each location.

4. Select PPE and enforce safe work practices

Select PPE appropriate to the calculated incident energy at the stated working distance. Energized work requires justification, a job briefing, and procedures such as lockout or tagout whenever feasible.

5. Train and qualify personnel

Only qualified workers may perform tasks that expose them to electrical hazards. Retraining is required at defined intervals or when work practices or equipment change. Hallam-ICS provides qualified worker training that aligns with NFPA 70E program elements.

6. Review and update

Update the assessment when modifications affect available fault current, protective device clearing time, or system configuration. Many organizations adopt a review cycle not to exceed five years to keep labels accurate and procedures aligned. For practical planning, see five benefits of completing a 5-year arc flash update.

Practical Improvements You Can Expect

Lower incident energy through tuning.
Adjusting protective device settings and improving coordination can reduce clearing times and lower calculated incident energy. This often enables lighter, more workable PPE without sacrificing protection.

Targeted equipment upgrades.
The study frequently flags slow or underrated devices that inflate risk. Replacements, current-limiting strategies, zone-selective interlocking, or maintenance switching can reduce incident energy at critical points.

Predictive maintenance alignment.
Integrating infrared thermography inspections with your electrical safety program helps find loose connections and overloaded components before they fail, which strengthens reliability and reduces unplanned outages. To see how these tools work together, explore the benefits of combining infrared thermography with an arc flash study.

Budgeting and standardization.
For budgeting and stakeholder alignment, review 10 steps to consider when budgeting for arc flash safety.

If you are comparing providers, this overview of the benefits of standardizing arc flash programs and electrical safety plans explains how consistent methods and documentation improve outcomes.

Planning Your Arc Flash Study

1. Define scope across sites, voltage classes, and equipment types.
2. Gather available one-lines, device settings, and utility data.
3. Complete field verification of conductor lengths, device types, and enclosures.
4. Build or update the system model and run short-circuit, coordination, and incident energy calculations.
5. Apply updated labels and hold a turnover review with operations, maintenance, and EHS.
6. Integrate results into procedures, PPE matrices, job plans, and training.
7. Schedule updates after system changes and as part of a five-year cycle.

Frequently Asked Questions

What are the NFPA 70E arc flash study requirements?
NFPA 70E requires a documented electrical hazard risk assessment that includes arc flash hazard evaluation, field labeling to guide PPE and boundaries, qualified worker training, and periodic review or update when conditions change.

How often should an arc flash study be updated?
Review after any significant electrical change and at regular intervals that typically do not exceed five years. This keeps labels and procedures accurate and aligned with current conditions.

Can we reduce incident energy without replacing all gear?
Often, yes. Coordination tuning, faster relay or breaker settings, current-limiting strategies, zone-selective interlocking, or targeted upgrades can reduce clearing times and lower incident energy at the most critical locations.

Who should perform an arc flash study?
Use qualified engineers experienced with NFPA 70E programs and IEEE 1584 modeling. Clear scope definition, current one-liners, and field-verified data improve outcomes and shorten schedules.

Where does thermography fit in the program?
Infrared inspections complement your study by finding loose or overloaded connections before they fail. See the Hallam-ICS perspective on the benefits of combining infrared thermography with an arc flash study.

Talk with Our Electrical Safety Team Today

Protecting your people and maintaining reliable operations starts with accurate data and applied engineering. Hallam-ICS delivers turnkey electrical safety solutions, including arc flash studies, labeling, training, and practical mitigation tailored to your facility’s risk profile.

Let’s discuss how we can help you build or update your NFPA 70E program.

About Hallam-ICS

Hallam-ICS is an engineering and automation company that designs MEP systems for facilities and plants, engineers control and automation solutions, and ensures safety and regulatory compliance through arc flash studies, commissioning, and validation. Our offices are located in Massachusetts, Connecticut, New York, Vermont, North Carolina  and Texas, and our projects take us world-wide.