The Risk Is Real — and Often Unverified In most industrial plants, maintenance personnel work near energised electrical equipment regularly. The immediate risk of electrical shock or arc flash exists at every such interaction. Yet the actual hazard level at a given panel or switchboard is rarely quantified with precision. PPE is worn, procedures are followed, and the assumption is that the system is adequately protected. That assumption is frequently unverified. Electrical shock and arc flash are not the same hazard. They have different causes, different injury mechanisms, and require different engineering controls. Understanding the distinction is the starting point for any credible risk reduction effort. More importantly, the controls that reduce arc flash incident energy at an industrial facility are engineering decisions, not procedural ones. They depend on system data, fault current calculations, and protection coordination — not on safety culture alone. This blog explains what determines shock and arc flash risk at the system level, which engineering controls meaningfully reduce that risk, and what Indian and international standards require of industrial facilities operating energised electrical equipment. What Makes Electrical Shock and Arc Flash Different Hazards? Electrical shock occurs when current passes through the human body. Arc flash is a sudden release of electrical energy through ionised air, producing intense heat, pressure, and light around the fault point. Both hazards exist at energised equipment, but they are controlled by different means. Shock protection depends on insulation, approach boundaries, and rated PPE. Arc flash risk reduction depends on limiting incident energy at the source through engineering controls. The distinction matters because many facilities treat PPE as the answer to both hazards. Arc-rated clothing reduces burn injury from arc flash. Rubber insulating gloves and insulated footwear address shock risk. But neither eliminates the underlying hazard. A worker wearing appropriate PPE is still exposed to an arc flash event of unknown energy if the system has not been studied. NFPA 70E defines two distinct boundaries around energised electrical equipment: the shock protection boundary, determined by voltage, and the arc flash protection boundary, determined by calculated incident energy. IS 18732 covers equivalent electrical safety practice obligations for Indian industrial facilities. Both frameworks require that these boundaries be established before energised work is performed. ⚡ Two Distinct Hazards — Two Distinct Engineering Controls ⚠️Shock: Current through the body — controlled by insulation, boundaries & rated gloves 🔥Arc Flash: Energy release through ionised air — controlled by incident energy reduction 🦺PPE reduces injury severity — it does not eliminate the hazard at the source What Determines Arc Flash Incident Energy at Your Facility? Arc flash incident energy is determined by two variables: the available fault current at a given bus and the time taken by the upstream protective device to clear that fault. Higher fault current and longer clearance time both increase incident energy. Relay coordination controls clearance time. Short circuit analysis establishes fault current. Without both studies, incident energy at any point in the system is unknown. The relationship between fault clearance time and incident energy is defined in IEEE 1584-2018, the standard for arc flash hazard calculations. Even modest reductions in relay operating time — through a proper relay coordination study — can reduce incident energy significantly. This is why relay coordination is not just a protection engineering task; it is a direct input to arc flash risk management. Engineering Controls That Reduce Risk at the Source Engineering controls reduce the hazard itself, before a worker is ever near the equipment. They are more effective than administrative controls or PPE, which manage exposure after the hazard exists. Several engineering-level interventions commonly reduce arc flash and shock risk in industrial systems. Relay Coordination Study — determines the time-current settings of all protective devices in the distribution network. Proper coordination ensures that the device nearest the fault operates first, clearing the fault quickly. Faster clearance means lower incident energy. Settings that have not been reviewed after equipment changes or maintenance may no longer produce the clearance times originally assumed. Short Circuit Analysis — establishes the available fault current at every bus. This is the primary input to both relay coordination and arc flash calculations. Equipment ratings must also be verified against these calculated values. A short circuit analysis also helps verify whether electrical equipment can safely handle actual fault current levels. Equipment that is not properly rated can increase the risk of electrical failure and arc flash incidents. Energy-Reducing Maintenance Switching — where de-energisation is not practical, this can lower incident energy during planned maintenance activities. This modifies the protection scheme temporarily to reduce fault clearance time during the specific period that work is being performed. It is a targeted control, not a permanent substitute for a coordination study. Has your facility's relay coordination been reviewed since the last equipment change? Outdated settings are one of the most common unverified risks in industrial plants. Discuss Your Facility → Relevant Standards and Regulatory Requirements CEA Safety Regulations 2023 and IEEE 1584-2018 together define what a compliant risk reduction approach looks like for industrial facilities. The full regulatory framework applicable to Indian industrial plants is as follows: Standard / Regulation Relevance to Shock / Arc Flash Risk Reduction CEA Safety Regulations 2023 Regulations 40–41 require protection systems to be maintained in correct working condition with documented and periodically verified settings. Earthing obligations link to IS 3043:2018. IEEE 1584-2018 Defines the arc flash incident energy calculation method. Fault clearance time and fault current are the primary inputs. Review required every 5 years or after major system changes. NFPA 70E Shock protection and arc flash protection boundaries. PPE selection based on calculated incident energy. Energised work requirements. IS 18732 Indian electrical safety practices including protection system maintenance obligations for industrial facilities. IS 3043:2018 Earthing and grounding system requirements. Complements shock protection controls at the equipment level. Practical Risks Faced by Industrial Facilities The most common risk in industrial plants is not a single catastrophic event. It is the gradual drift of protection settings away from the system's actual configuration, as equipment is added, modified, or replaced without a follow-up coordination study. The protection scheme then operates on assumptions that no longer reflect reality. Several conditions in industrial facilities raise shock and arc flash risk over time: Protective device settings changed during maintenance without proper review — can lead to incorrect fault detection and delayed fault clearing. The result may be nuisance tripping on normal load, or delayed tripping on an actual fault. Outdated arc flash labels — labels on equipment may reference incident energy values from a study performed years earlier. If the system has changed since then, those values may understate the actual hazard. Workers selecting PPE based on outdated labels are not adequately protected. Where PPE Fits — and Where It Does Not Substitute for Engineering Controls PPE is the last layer of protection. It reduces the severity of injury if a hazard occurs. It does not prevent the fault. It does not reduce incident energy. Selecting PPE without calculated incident energy values — derived from a formal arc flash study — means the selection is based on category assumptions rather than the actual hazard level at each equipment location. Lockout/Tagout (LOTO) procedures, combined with earthing per IS 3043:2018, address shock risk when equipment is de-energised. Energised work requires a different set of controls entirely, including a written justification that de-energisation was not feasible. "PPE is the last layer of protection — it reduces injury severity if a hazard occurs. It does not prevent the fault, and it does not reduce incident energy. The engineering controls come first." SAS Powertech Pvt. Ltd. — Industrial Arc Flash Risk Reduction Framework When Should a Facility Commission an Arc Flash and Shock Hazard Study? An arc flash and shock hazard study is required at commissioning and must be repeated after any significant system change: new loads, transformer additions, DG commissioning, or relay setting modifications made during maintenance. IEEE 1584-2018 and NFPA 70E both indicate a review period of at least every five years, or sooner if the system configuration changes. CEA Safety Regulations 2023 (Regulations 40–41) require protection systems to be maintained in correct working condition with verified settings. A relay coordination study, combined with a short circuit analysis and arc flash study, provides the engineering basis for that verification. Trigger Events Requiring a Study Review New loads or equipment additions — any significant change to the connected load changes fault current levels throughout the system. Transformer additions or replacements — directly affects available fault current at downstream buses. DG set commissioning — introduces new fault current contribution paths not present in the original study. Relay setting modifications during maintenance — changes fault clearance time, which directly affects incident energy calculations. Periodic review — IEEE 1584-2018 and NFPA 70E require review at least every five years regardless of system changes. Conclusion Reducing the risk of electrical shock and arc flash in an industrial plant is an engineering outcome. It requires knowing the actual fault current at each bus, confirming that protective devices are coordinated to clear faults within defined time windows, and verifying that incident energy values at every equipment location are current and accurately labelled. CEA Safety Regulations 2023, IEEE 1584-2018, IEC 60909, and NFPA 70E together define the technical and regulatory framework for this work. Meeting that framework is not a one-time activity. It requires periodic review and update as the system evolves. The plants that manage these risks most effectively are those that treat protection coordination and arc flash analysis as live engineering documents — not commissioning-era reports filed and forgotten. "The plants that manage these risks most effectively treat protection coordination and arc flash analysis as live engineering documents — not commissioning-era reports filed and forgotten." SAS Powertech Pvt. Ltd. — Engineering Assurance for Industrial Electrical Safety Frequently Asked Questions What is the difference between electrical shock and arc flash? Electrical shock occurs when current passes through the human body, typically through direct contact with an energised conductor. Arc flash is a sudden release of electrical energy through ionised air between conductors or to ground, producing extreme heat, pressure, and light. The two hazards coexist at energised equipment but require different controls. Shock is addressed through insulation, rated gloves, and approach boundaries. Arc flash is addressed through incident energy reduction, correct PPE selection based on calculated values, and engineering controls that limit fault clearance time. Does relay coordination reduce arc flash risk? Yes. Relay coordination controls fault clearance time, which is a direct input to arc flash incident energy calculation under IEEE 1584-2018. Reducing clearance time reduces incident energy at the fault point. Is an arc flash study mandatory under CEA Safety Regulations 2023? CEA Safety Regulations 2023 (Regulations 40–41) require that protection systems be maintained in correct working condition with documented and periodically verified settings. An arc flash study provides the engineering basis for those settings and for PPE selection, and is aligned with the regulatory obligation to maintain a safe working environment under the Indian Electricity Rules 1956. If your facility has not yet conducted a relay coordination or arc flash hazard study, this is the right time. SAS Powertech conducts independent arc flash studies, relay coordination studies, and short circuit analyses for industrial facilities across India. Our deliverables are structured to meet CEA 2023 and IEEE 1584-2018 requirements. info@saspowertech.com 9665525694 / 9763003222 Request a Study →