As electrical safety regulations and industry standards evolve, arc flash awareness and protection has never been more essential. Despite its severity, arc flash remains one of the least understood hazards in the electrical industry, with minimal awareness of how arc flash occurs, how fast it develops, or how to efficiently assess and mitigate the risk.

Many electricians and engineers complete their training typically focusing on electrical shock as the principal risk, with little knowledge of arc flash. This lack of understanding, combined with the development of existing standards and increasingly complex electrical systems, creates a critical gap in industry knowledge.

At Group Metropolitan, we aim to highlight and educate on this hidden killer in our industry, providing understanding and context, supporting through risk assessments, and implementing safe systems that protect both people and infrastructure.

What is arc flash?

An arc flash occurs when a short-circuit fault ionises the air, turning it from an insulator into a conductor. Once the air becomes conductive, fault current can flow freely across the gap, releasing immense thermal energy, light, pressure and sound.

Arc flash can produce:

• Temperatures exceeding 19,000°C
• Pressure waves capable of causing blunt trauma
• Vaporisation of metal components
• Blinding light

Under normal conditions with well-maintained equipment and trained operators, the risk is low. But faults, poor maintenance, incorrect operation, missing covers or aging switchgear dramatically increase the risk of an arc event.

Why is awareness low?

In the UK, electrical training frameworks historically don’t prioritise arc flash education. Many qualified engineers complete:

• NVQ Level 3
• AM2
• City & Guilds 2391

…without ever learning what an arc flash is or how to assess it.

This gap leaves a large proportion of the workforce competent in electrical installation and electric shock prevention, but unprepared for the second major hazard of electricity.

Why arc flash risk assessment is difficult

Unlike other electrical hazards, arc flash does not behave predictably. Two distribution boards may appear identical but be drastically different due to:

• Internal condition
• Fault level
• Protection settings
• Environmental factors

This creates a critical “two- door analogy” - there are two identical doors but the danger behind each one is completely different. Without opening the door, you don’t know the hazard, but opening the door is a hazard in itself.

This “Catch-22” situation means you need an arc flash risk assessment to access live parts, but you need to access live parts to gather the data for the assessment. This uncertainty is central to the challenge of arc flash management.

Hierarchy of arc flash risk controls

Group Metropolitan applies a structured, safety-first methodology based on the recognised hierarchy of risk controls:

1. Elimination
   1. De-energising equipment
   2. Designing out live interactions
      
2. Minimisation / Control
   1. Arc-protected switchgear
   2. Temporary protection setting adjustments
   3. Remote switching solutions
   4. Fully insulated busbars
      
3. Safe systems of work
   1. Permit-to-work and authorisation systems
   2. SOPs for switching
   3. Routine maintenance and inspections
   4. Correct tools and equipment
      
4. Information & Training
   1. Arc flash awareness / training
   2. Refresher training
   3. Toolbox talks
   4. Warning signage
      
5. Personal Protective Equipment (PPE) - as a last resort
   1. Multi-layer arc-rated PPE

PPE does not prevent an arc flash, it only mitigates the injuries, and even then, only partially.

Simplifying the risk assessment

To support our engineers and bring clarity to selecting arc flash PPE, Group Metropolitan has developed a simplified internal arc flash process. The process involved:

Gaining greater understanding of IEEE 1584 (2018)

1. Creating a user-friendly interface
2. Developing typical values for common equipment
3. Overestimating PPE to remain on the safe side

This tool allows non-specialist engineers to select the equipment type and receive:

• Estimated incident energy
• Flash protection boundary
• Minimum PPE category

Practical Limitations

All arc flash calculations, even those built on IEEE 1584, share one unavoidable truth: Arc flash is inherently unpredictable.

The calculations remain estimates based on assumptions. The actual hazard depends on:

• Mechanical condition
• Age of equipment
• Contamination
• Protection performance
• Human factors
• Manufacturing variances

Trusted expertise for a hidden hazard

With evolving regulations, infrastructure demands, and a skills gap in arc flash awareness, the need for competent support has never been greater. Group Metropolitan supports building owners, facilities managers, and duty holders in assessing and controlling this complex hazard.

Despite extensive study, research, modelling, and tool creation, one truth stands firm: There are too many unknown variables to ever be completely confident in arc flash predictions.

This uncertainty is precisely why:

• Routine maintenance matters
• Safe systems of work matter
• Awareness matters
• PPE matters
• Respect for the hazard matters

Group Metropolitan's experienced teams, led by trained specialists, ensure that organisations are not only compliant but operating to the highest safety standards.

Arc flash may be a hidden danger, but the responsibility to manage it is very real.