Arc Flash Risk in Industrial Control Panels (Roll Forming Machine Safety Guide)

Arc Flash Risk in Industrial Panels

Electrical Hazard Analysis for Roll Forming & Coil Processing Machines

Arc flash is one of the most severe electrical hazards in industrial environments.

In roll forming and coil processing lines, control panels often contain:

• High fault current capacity

• VFD drives

• Busbars

• MCCBs

• Motor starters

• Distribution assemblies

If a short circuit occurs under load, an arc flash event can produce:

• Temperatures above 19,000°C

• Blast pressure wave

• Molten metal spray

• Severe burns

• Equipment destruction

• Fatal injuries

Arc flash risk must be evaluated under:

• NFPA 70E (US)

• IEC 61482 (International PPE standard)

• IEEE 1584 (Arc flash calculation method)

This guide explains arc flash fundamentals, risk calculation basics, labeling requirements, and mitigation strategies for roll forming machine electrical panels.

1) What Is Arc Flash?

Arc flash occurs when:

An unintended electrical arc forms between conductors or between conductor and ground.

Common causes:

• Loose connection

• Tool drop inside panel

• Insulation breakdown

• Dust accumulation

• Incorrect breaker rating

• Maintenance error

Arc flash is different from shock hazard.

It is a thermal and pressure explosion.

2) Why Roll Forming Panels Are High Risk

Roll forming machines often have:

• 400–480V supply

• High horsepower motors

• Large fault current availability

• Multiple branch circuits

The higher the available fault current:

The more severe the arc flash energy.

Industrial environments increase risk during:

• Commissioning

• Troubleshooting

• Live testing

• Maintenance

3) Available Fault Current

Arc flash severity depends heavily on:

Available short circuit current.

Example:

If facility provides 65kA fault current:

Panel must be rated appropriately.

Higher fault current → greater arc energy.

Fault current must be known before performing risk analysis.

4) Arc Flash Incident Energy

Incident energy measured in:

Calories per square centimeter (cal/cm²).

Higher cal/cm² → higher burn severity.

Typical PPE levels:

• 1.2 cal/cm² → Basic protection
• 8 cal/cm² → Moderate
• 40 cal/cm² → Severe industrial hazard

Proper calculation determines required PPE.

5) IEEE 1584 Calculation Overview

Arc flash incident energy calculation depends on:

• System voltage

• Available fault current

• Protective device clearing time

• Working distance

• Gap between conductors

Longer breaker trip time increases energy dramatically.

Fast clearing reduces risk.

6) Protective Device Clearing Time

Breaker speed critical.

If breaker trips in:

0.05 seconds → lower arc energy
0.5 seconds → significantly higher energy

Selective coordination must balance:

Reliability vs safety.

Slow upstream breaker increases hazard.

7) Arc Flash Label Requirements

Panels must display:

• Nominal voltage

• Available fault current

• Incident energy level

• Required PPE

• Approach boundaries

Label must be visible and durable.

Required under NFPA 70E in US.

8) Word-Based Arc Flash Energy Flow

• Fault Occurs →
• Arc Initiates →
• Current Flows →
• Breaker Trips →
• Arc Extinguishes

Incident energy equals:

Energy released during clearing time.

Reduce clearing time → reduce energy.

9) Busbar Design & Arc Risk

Improper busbar spacing increases risk.

Busbars must:

• Maintain required spacing

• Be insulated or shrouded

• Be properly supported

Loose connections increase arc initiation risk.

10) Panel Design Strategies to Reduce Arc Risk

Mitigation strategies:

• Use current-limiting breakers

• Reduce available fault current

• Increase breaker speed

• Use arc flash detection systems

• Add zone selective interlocking (ZSI)

• Improve compartmentalization

Design stage decisions impact hazard level.

11) VFD & Arc Flash Considerations

VFDs include:

• DC bus capacitors

• High internal energy storage

Even after power removal:

Capacitors remain charged.

Discharge time must be respected before servicing.

12) Maintenance & Live Work Risk

Arc flash risk increases during:

• Live voltage measurement

• Troubleshooting under load

• Panel door open conditions

NFPA 70E discourages live work unless justified.

Lockout/tagout must be used.

13) Common Arc Flash Causes in Roll Forming Panels

1. Loose terminals

2. Poor torque during installation

3. Dust & metal shavings

4. Inadequate breaker rating

5. Improper SCCR calculation

6. Tool contact with energized bus

7. Improper cable routing

Regular inspection reduces risk.

14) Short Circuit Current Rating (SCCR)

Panel SCCR must exceed available fault current.

If facility fault current > panel SCCR:

Panel unsafe.

SCCR labeling required in US.

Incorrect SCCR is major compliance failure.

15) Grounding & Bonding Impact

Proper bonding:

Reduces likelihood of uncontrolled arcing.

Poor grounding:

Increases fault path instability.

Protective earth must be low resistance.

16) Arc Flash Boundary Zones

Three main zones:

• Limited approach boundary
• Restricted approach boundary
• Arc flash boundary

Working within boundary requires PPE.

Distance increases safety.

17) PPE Requirements

Depending on calculated energy:

PPE may include:

• Arc-rated clothing

• Face shield

• Gloves

• Helmet

• Flame-resistant suit

Improper PPE selection increases injury severity.

18) Buyer Strategy (30%)

If purchasing a roll forming machine for US or high-regulation markets, verify:

1. Panel SCCR marked

2. Available fault current evaluated

3. Arc flash labeling provided

4. Breaker clearing times documented

5. Current-limiting protection used where possible

6. Proper torque documentation available

7. Busbar shrouding installed

8. Maintenance safety instructions included

Red flags:

• “No SCCR marking.”
• “No arc flash label.”
• “Breaker size unknown.”

These increase liability exposure.

6 Frequently Asked Questions

1) Is arc flash the same as electric shock?

No. Arc flash is thermal explosion hazard.

2) Is arc flash analysis mandatory?

In US industrial environments, yes under NFPA 70E.

3) Does CE require arc flash label?

Not directly like NFPA 70E, but risk assessment required.

4) How do I reduce arc energy?

Reduce clearing time and fault current.

5) Is 480V more dangerous than 400V?

Higher voltage increases arc intensity potential.

6) What is most common panel risk?

Loose terminals and incorrect SCCR rating.

Final Engineering Summary

Arc flash risk in roll forming control panels depends on:

• Available fault current

• Breaker clearing time

• Busbar spacing

• Protective device rating

• Panel SCCR

• Maintenance practices

Proper mitigation requires:

• Accurate fault current calculation

• Current-limiting protection

• Arc flash labeling

• Proper grounding

• Routine inspection

• PPE compliance

In industrial roll forming environments, arc flash risk management is not optional — it is a core electrical safety requirement that protects personnel, equipment, and legal liability.