An arc flash study is the engineering analysis used to identify electrical hazards, calculate incident energy, establish arc flash boundaries, and create equipment labels for safe maintenance work. For industrial plants, manufacturing lines, warehouses, healthcare facilities, and large commercial buildings, the study gives safety teams a defensible basis for energized-work procedures and PPE selection.
The practical trigger is simple: if employees or contractors may work on or near energized electrical equipment, the owner needs a documented method for recognizing the hazard and controlling the risk. That is why arc flash studies are commonly performed for switchboards, switchgear, motor control centers, panelboards, transformers, industrial control panels, and service equipment.
When is an arc flash study required?
An arc flash study is required when a facility must evaluate electrical hazards for equipment that could be serviced or maintained while energized. New construction, major service upgrades, new transformers, replacement switchgear, generator additions, large motor loads, protective-device setting changes, and utility service changes are all common moments to perform or update a study.
Existing facilities also need a current study when labels are missing, one-line diagrams are outdated, protective settings are unknown, or the available fault current has changed. In those cases, field data collection and system modeling are often needed before accurate labels can be issued.
Is an arc flash study required by OSHA?
OSHA does not usually describe compliance as a single named “arc flash study.” Instead, OSHA requires employers to protect workers from recognized electrical hazards and to use safe work practices for electrical work. NFPA 70E is the consensus standard most facilities use to translate that obligation into a documented risk assessment, equipment labeling, PPE requirements, and energized-work procedures.
A complete arc flash study helps demonstrate that the employer has identified the hazard, evaluated the severity, communicated the risk at the equipment, and equipped qualified workers with the information needed to work safely.
NFPA 70E five-year update rule
NFPA 70E requires the arc flash risk assessment to be reviewed periodically, at intervals not to exceed five years. The five-year review is not just an administrative date check. It confirms that the model still reflects the real electrical system, utility source, protective-device settings, equipment configuration, and operating conditions.
Facilities should update sooner than five years when changes can affect fault current or clearing time. Examples include a new utility transformer, service upgrade, generator or solar interconnection, switchgear replacement, feeder reconfiguration, added production equipment, changed breaker settings, or replaced fuses. These changes can materially alter incident energy and the PPE shown on labels.
What a complete study should include
Hazard identification
Document shock and arc flash hazards on equipment that may be inspected, adjusted, serviced, or maintained while energized.
Incident-energy analysis
Model available fault current and protective-device clearing times to calculate incident energy and arc flash boundaries.
Labels and PPE
Apply equipment labels that support safe work planning, PPE selection, approach boundaries, and energized-work procedures.
Five-year review cycle
Review the arc flash risk assessment at least every five years, or earlier after utility, transformer, switchgear, feeder, or protective-device changes.
How O'Farrell Engineering supports compliance
O'Farrell Engineering performs field data collection, one-line verification, SKM PowerTools modeling, short-circuit analysis, protective-device coordination, incident-energy calculations, and equipment labeling for Arizona commercial and industrial facilities. The deliverable is built for both engineering accuracy and practical use by maintenance teams.