Electrical safety is the most critical element of managing power systems, whether within industrial facilities, commercial buildings, or complex infrastructure networks. Among the tools used to evaluate electrical hazards and system performance, two studies stand out for their impact and importance: the Arc Flash Assessment and the Fault Level Assessment. While they often appear as separate parts of an electrical safety management system, these assessments are deeply interconnected. When carried out together, they deliver a far more accurate understanding of electrical risk and provide the analytical foundation for reducing incident energy, reducing potential failure, protecting equipment and improving system reliability.
Understanding how these studies complement one another, and why they should not be treated in isolation, is essential for anyone responsible for electrical safety. This article explores why the relationship between these two assessments is so significant.
What is a Fault Level Assessment?
A Fault Level Assessment determines the magnitude of electrical current that could flow when a fault occurs, such as a bolted short-circuit. Instead of focusing on technical equations, it is more helpful to view the study as defining the overall electrical strength and behaviour of a system under abnormal conditions.
A fault introduces stress into the system. The higher the fault current, the greater the mechanical and thermal forces placed on equipment. If this level exceeds the rating of switchgear, cables, or protective devices, the risk of damage increases considerably.
A fault level study helps answer several essential questions:
- Could the equipment withstand the highest possible fault?
- Will protective devices operate quickly enough to isolate the fault?
- Are there areas of the system where the fault level exceeds equipment ratings?
- Do system changes alter the fault current distribution?
A Fault Level Assessment effectively builds the foundation on which all further protection decisions rely. Without it, there is no reliable starting point for understanding system hazards.
What an Arc Flash Assessment Sets Out to Achieve
An Arc Flash Assessment evaluates the thermal energy released in the event of an arc fault. In an arc event, electrical current leaves its intended path and travels through the air, creating a violent release of heat, pressure and light. The goal of an arc flash assessment is to determine how much energy would be present at a given working distance and to identify the protective measures needed to safeguard personnel.
The assessment includes evaluating:
- Incident energy levels
- Arc flash boundaries
- Potential arc locations
- Safe approach distances
- The influence of clearing times and protection settings
- Possible mitigation methods
In simple terms, while the Fault Level Assessment tells us how large a fault could be, the Arc Flash Assessment tells us what that fault would mean for people working near energised equipment.
Why Fault Level Data Is the Input for Arc Flash Analysis
An Arc Flash Assessment relies on accurate fault current information, because the fault current magnitude directly affects the amount of energy released during an arc fault. If the available fault current is underestimated, the incident energy calculations will also be underestimated. This creates the potential for unsafe working boundaries and incorrect PPE recommendations.
Likewise, overestimating fault current can lead to unnecessarily conservative boundaries or exaggerated PPE requirements, which can reduce productivity without improving safety.
Because fault level defines the starting point of the arc flash calculation, both assessments must be conducted using the same data model and system configuration. If the data does not match, the two studies can contradict each other and create uncertainty.
The Role of Protection Coordination Between the Two Studies
Protection coordination provides the essential link between fault levels and arc flash energy. Protection devices, such as circuit breakers, fuses and relays, must operate in a coordinated manner to ensure faults are isolated rapidly and selectively.
Protection settings have a direct influence on arc duration, which then affects:
- The level of incident energy
- The size of the arc flash boundary
- The risk posed to maintenance personnel
Each scenario leads to gaps in the safety picture. Performing both assessments together provides:
- Consistency across all calculations
- A shared understanding of protective device performance
- More reliable recommendations
- Greater confidence in mitigation decisions
- Improved compliance with UK standards and best practice
This integrated approach is especially important following system upgrades, equipment replacements or operational changes.
5 Benefits for Facility Owners and Duty Holders
Combining Arc Flash and Fault Level Assessments delivers several practical advantages:
1. Enhanced safety for operatives
Staff have accurate information about safe working distances, boundaries and PPE.
2. Reduced equipment damage
Protection devices operate within intended parameters, reducing fault stress on the system.
3. Improved system reliability
Better coordination reduces nuisance trips and improves operational continuity.
4. Clearer decision-making
Duty holders receive a complete, cohesive safety analysis rather than fragmented reports.
5. Future-proofing
System upgrades and equipment changes can be modelled accurately.
How Covol Deliver a Combined Approach
Our experienced electrical engineers at Covol specialise in delivering Arc Flash and Fault Level Assessments as part of an integrated process. Our approach avoids the inconsistencies that arise when assessments are performed separately. We focus on clarity, accuracy and actionable recommendations, ensuring that duty holders understand not only the risks but the practical steps required to reduce them.
Find more information about Covol’s approach to Arc Flash and Fault Level Assessment today, and don’t hesitate to get in touch for further advice.
