Arc flash · India
Arc flash hazard analysis & CEA 2023 compliance for Indian plants
An arc flash hazard is the release of energy from an electric arc between live conductors or between a conductor and earth. An arc flash hazard analysis calculates how much of that energy reaches a worker at a stated working distance, in cal/cm², and fixes the arc flash boundary around the equipment. VB Engineering performs that analysis for Indian plants and installs the label the calculation produces.
VB Engineering is a leader in conducting arc flash risk assessments in India, with an impeccable record of 1,000+ studies delivered since 2014.
Reviewed August 2026
What is an arc flash hazard
A dangerous condition associated with the release of energy caused by an electric arc. An arc flash hazard analysis starts with gathering up-to-date equipment information, then performing a detailed analysis comprised of a load flow study, a short circuit study and a protective device coordination study, as well as an equipment evaluation to determine that the current withstand rating is acceptable.
Arc flash and shock hazards are recognised as particularly dangerous and fairly frequent occurrences that put the lives and health of electrical workers at significant risk. Those incidents most often occur when personnel are required, or choose, to work on electrical equipment while it is in an electrically energised condition.
What decides how severe it is
Three key factors determine the intensity of an Arc Flash on personnel. These factors are the quantity of fault current available in a system, the time taken for successful short circuit interruption, and the distance an individual is from a fault Arc. Various design and equipment configuration choices can be made to affect these factors and in turn reduce the Arc Flash hazard.
Each of the three is a number the analysis produces. Fault current comes out of the short circuit study. Clearing time comes out of the protection coordination study. Working distance is set by how the equipment is actually operated. Change any one of them and the incident energy at the door changes.
What is arc flash analysis?
A study investigating a worker's potential exposure, conducted for the purpose of injury prevention and the determination of safe work practices and appropriate levels of PPE. We at VB Engineering follow NFPA 70E for arc flash analysis. Our engineers calculate to IEEE 1584, which sets out the method for arc flash studies.
Electrical hazard analysis includes load flow, short circuit, harmonic and contingency analysis. We also perform protective device coordination.
What the arc rating on PPE means
The Arc rating is the maximum incident energy resistance demonstrated by a material prior to breaking open (a hole in the material) or necessary to pass through and cause with 50% probability a second or third degree burn.
There are many methods of arc flash protection. These include personal protective equipment and modifying the design and configuration of the electrical equipment itself. The second is the one that removes the hazard rather than dressing for it.
The arc flash boundary and incident energy
Incident energy is the thermal energy that arrives at a surface a stated distance from the arc, expressed in calories per square centimetre, cal/cm². It is quoted at a working distance, commonly 18 inches for low voltage equipment, because that is roughly where a worker's face and chest sit when a panel door is open.
The arc flash boundary is the distance at which incident energy falls to 1.2 cal/cm², equivalently 5.02 J/cm². That figure is not arbitrary. 1.2 cal/cm² is the level at which exposed skin receives a second degree burn. Inside that line, arc rated protection is required. Outside it, it is not.
The numbers a plant should know
| Figure | What it means |
|---|---|
| 1.2 cal/cm² | the arc flash boundary · second degree burn threshold on exposed skin |
| 5.02 J/cm² | the same figure in SI units |
| 4, 8, 25 and 40 cal/cm² | the four arc flash PPE categories |
| 40 cal/cm² | the ceiling · no standard PPE category covers above it |
| 18 inches | the working distance incident energy is commonly quoted at |
Above 40 cal/cm² the NFPA 70E PPE categories run out. Arc rated clothing is manufactured above that level, but the arc blast pressure becomes a hazard that clothing does not address, so wearing it is not a guarantee. At that level the work is de-energised, or the protection is changed so the energy comes down. A study that returns a figure above 40 and stops there has not finished the job.
Arc flash on Indian plant equipment
An Indian plant does not describe its electrical system in the words a standard uses. It talks about HT and LT panels, 11 kV switchgear, 415 V distribution boards, the MCC and the PCC. The hazard behaves differently across them, and so does the study.
| Equipment | What drives the hazard |
|---|---|
| 11 kV HT switchgear | high fault levels, but relay clearing times are usually fast. The exposure that bites is a coordination setting nobody has revisited since commissioning |
| 415 V LT panels and distribution boards | where incident energy is most often highest · substantial fault current with slower upstream clearing, and the equipment a technician opens most often |
| MCC and PCC lineups | many doors, many operators, repeated daily access. The label has to be on every door, not on the incomer |
| Transformer secondaries | the transition point where an HT fault level becomes an LT incident energy figure. Read wrong, the whole downstream board is wrong |
A plant with an ageing LT board and a modern HT panel usually finds its worst number on the old board, not the one that looks dangerous. That is the single most common surprise in an Indian arc flash study.
Standards and regulations that apply in India
Arc flash work at an Indian plant is measured against the following.
- NFPA 70E · electrical safety in the workplace
- OSHA · occupational safety, referenced widely in Indian multinational practice
- NEC · the National Electrical Code
- CEA 2023 · Central Electricity Authority safety regulations
- Factories Act 1948
IEEE 1584 provides the calculation method used to determine the arc flash boundary and incident energy.
How we perform the analysis
We are electrical engineering consultants for arc flash analysis. Through an arc flash safety analysis, our engineers can offer alternatives to help your organisation reduce its people's exposure to arc flash energy. We provide integrated short circuit, time current coordination and equipment evaluation, the arc flash calculation and the arc flash labels, the flash protection and approach boundaries, and arc flash hazard training for your internal team.
The platforms we calculate on
We model and calculate on ETAP, SKM PowerTools (PTW) and CYME.
What you receive
Your report is delivered by VB Engineering, a leader among electrical safety audit companies in India. It carries the calculated incident energy and arc flash boundary for every studied bus, the protection settings that produced them, and the labels installed on the equipment.
Two of our own products carry the work forward after the report is signed. ElecTwin keeps the electrical asset record current, and VijAI PPEAI verifies at the panel door that the arc rating a worker is wearing matches the label on the equipment in front of them.
- Arc flash risk assessment · the study itself, scope and method
- Arc flash analysis in India · delivery at an Indian plant
- VB Arc360 · the programme that keeps the study, the labels and the training current
- Arc flash PPE · categories and selection
- Protective device coordination · where clearing time is fixed
- Short circuit analysis · where fault current is fixed
Questions we are asked
What is an arc flash hazard?
An arc flash hazard is the release of energy caused by an electric arc between live conductors, or between a conductor and earth. The energy arrives as heat, light, pressure and molten material. Its severity depends on the fault current available, how quickly the protection clears the fault, and how far the worker is standing from the arc.
What is arc flash hazard analysis?
It is a study of a worker's potential exposure, performed to determine safe work practices and the appropriate level of PPE. It comprises a load flow study, a short circuit study and a protective device coordination study, plus an equipment evaluation to confirm the current withstand rating is acceptable. The calculation is performed to IEEE 1584.
What is the arc flash boundary?
The arc flash boundary is the distance from the equipment at which incident energy falls to 1.2 cal/cm2. Inside that distance, arc rated protection is required. Outside it, it is not. The boundary is calculated for each item of equipment and printed on its label.
Why is the arc flash boundary set at 1.2 cal/cm2?
Because 1.2 cal/cm2, equivalently 5.02 J/cm2, is the level of incident energy at which exposed skin receives a second degree burn. The boundary is therefore the line beyond which an unprotected person is not expected to be seriously burned by the arc.
What is incident energy and what does cal/cm2 mean?
Incident energy is the thermal energy arriving at a surface a stated distance from the arc, measured in calories per square centimetre. It is always quoted with a working distance, commonly 18 inches for low voltage equipment, because that is approximately where a worker's face and chest sit when a panel door is open.
What happens above 40 cal/cm2?
40 cal/cm2 is the ceiling of the four NFPA 70E PPE categories. Arc rated clothing is manufactured above that level, but the arc blast pressure becomes a hazard that clothing does not address, so wearing it is not a guarantee of protection. At that level the work is performed de-energised, or the protection is changed so that the incident energy comes down.
What are the arc flash PPE categories?
There are four, rated at 4, 8, 25 and 40 cal/cm2. The category selected for a task must have an arc rating at or above the incident energy calculated for that equipment at the working distance. The arc rating is the maximum incident energy a material resists before breaking open or before a second or third degree burn becomes probable.
Which standards and regulations apply to arc flash in India?
Arc flash work at an Indian plant is measured against NFPA 70E, OSHA, the NEC, CEA 2023 and the Factories Act 1948. IEEE 1584 provides the calculation method used to determine the arc flash boundary and the incident energy.
What causes an arc flash on an 11 kV panel?
Most commonly a failed insulator or bushing, a dropped tool, a loose connection that has been heating for months, or vermin bridging phases. On 11 kV HT switchgear the fault current is high but relay clearing is usually fast, so the exposure that matters is often a coordination setting that has not been revisited since commissioning.
How does an arc flash study differ from an electrical safety audit?
An arc flash study is a calculation. It returns incident energy, the arc flash boundary and the required PPE for each item of equipment, and it produces labels. An electrical safety audit is broader: it covers earthing, thermography, lightning protection, work permits and compliance, and it usually contains an arc flash risk assessment inside it.
Scope an arc flash hazard analysis for your plant
Tell us the voltage levels, the number of boards and whether a current single line diagram exists. We will come back with a scope.