Η Αόρατη Ασπίδα: Γιατί η Ασφάλεια Υψηλής Ικανότητας Διακοπής είναι η Τελευταία Γραμμή Άμυνας της Εγκατάστασής σας

The Industry’s Silent Upgrade: Why Major Manufacturers Are Raising the Bar

Recently, a procurement manager raised a sharp question on a technical forum: “Why are major brands like Mersen, Littelfuse, and Bussmann quietly relabeling their Class R fuses from 200kA to 300kA interrupting ratings? Is this just a marketing gimmick, or a genuine safety advancement?”

The skepticism is understandable. In an industry where standards evolve slowly and conservatively, a 50% jump in performance specifications feels suspiciously like a sales tactic. After all, if 200kA (200,000 amperes) was sufficient for decades, why the sudden change?

Εδώ είναι η άβολη αλήθεια: It’s not marketing—it’s a response to an increasingly dangerous electrical grid. The transition to 300kA interrupting ratings isn’t about competitive positioning; it’s a symptom of a measurable problem in industrial power systems. Available fault currents at service entrances are rising due to utility infrastructure upgrades, grid modernization, and increased power density in industrial facilities. The “standard” protection of yesterday is becoming dangerously inadequate today.

At VIOX Electric, a B2B manufacturer of electrical equipment specializing in industrial protection systems, we’ve tracked this trend closely. The shift to higher breaking capacity isn’t optional—it’s essential for facility safety, equipment protection, and regulatory compliance. This article explains why high breaking capacity (HBC) fuses are no longer a luxury specification but your facility’s absolute bottom line for protection against catastrophic short-circuit events.

The 300kA Evolution: Not Marketing, But Engineering Necessity

For decades, 200kA interrupting rating represented the ceiling for industrial low-voltage fuses. Engineers designing systems in the 1990s and early 2000s confidently specified Class J, Class L, and Class R fuses with 200kA ratings, assuming this exceeded any realistic fault scenario. The calculation was simple: “My 1500 kVA transformer can’t possibly generate 200,000 amps of fault current at the secondary.”

That assumption is no longer universally valid.

Two Root Causes Driving Higher Fault Currents

1. Aging Infrastructure Replacement and Grid Modernization

Electrical utilities across North America are systematically replacing aging distribution transformers and upgrading substations. Modern transformers typically have lower impedance than units installed 30-40 years ago. According to IEEE fault current calculation standards (IEEE 551-2006), transformer impedance is the primary limiting factor in available short-circuit current.

When a utility replaces a 4% impedance transformer with a newer 3.5% impedance unit at the same kVA rating, the available fault current increases by approximately 14% instantly—without any changes to your facility’s electrical system. Facilities designed two decades ago for 50kA available fault current may now face 65kA or higher due solely to upstream utility modifications.

2. Industrial Park Densification and Lower System Impedance

As industrial parks expand and power demand increases, utilities install larger transformers closer to load centers. Shorter conductor runs between transformers and service entrances mean lower impedance paths—and higher prospective short-circuit currents. A facility that originally received power through 200 feet of conductor from a remote pad-mount transformer may now be served by a new unit installed just 50 feet from the building. This four-fold reduction in conductor length can increase available fault current by 20-30%.

The UL 248 Certification Reality

The appearance of 300kA-rated fuses isn’t speculative engineering—it reflects rigorous third-party testing. Under UL 248 standards (specifically UL 248-8 for Class J, UL 248-10 for Class L, and UL 248-12 for Class R fuses), manufacturers must demonstrate that fuses can safely interrupt the rated fault current without rupture, fire, or expulsion of conductive particles.

Class RK1 fuses with 300kA ratings have passed these tests at 300,000 amperes RMS symmetrical current—demonstrating containment, arc extinction, and safe interruption at levels that would destroy lower-rated devices. The upgrade to 300kA provides a larger safety margin as utility fault currents creep upward, ensuring protection equipment won’t become the weakest link during a catastrophic short circuit.

The Catastrophic Physics of Exceeding Breaking Capacity

The most dangerous procurement mistake in electrical protection is buying on price instead of breaking capacity. When comparing fuses, a generic 10kA-rated device may physically resemble a premium 200kA high breaking capacity (HBC) fuse. They might have similar dimensions, fit identical holders, and carry the same ampere rating. The price difference might be 3:1 or even 5:1.

But inside these superficially identical packages, the difference is literally life and death.

What Happens When Fault Current Exceeds Interrupting Rating

Breaking capacity (also called interrupting rating or rupturing capacity) defines the maximum current that a fuse can safely interrupt without being destroyed or causing an electric arc with unacceptable duration. This isn’t a suggested operating range—it’s a hard physical limit.

Consider a realistic scenario: Your facility has an available fault current of 65kA at the main service entrance (not uncommon in medium-sized industrial plants). During a short-circuit event—perhaps from equipment failure or accidental contact—the full 65,000 amperes attempts to flow through the protective fuse.

If that fuse has only a 10kA interrupting rating:

1. Element Melts: The fuse element vaporizes as designed, creating an arc.
2. Arc Energy Exceeds Containment: The arc generates temperatures exceeding 20,000°C and immense pressure inside the ceramic body.
3. Quartz Sand Fails: The arc-quenching medium (quartz sand) cannot absorb the massive energy release fast enough.
4. Pressure Ruptures Ceramic: The ceramic body—designed for 10kA energy levels—cannot withstand the mechanical stress from 65kA arc pressure.
5. Explosive Failure: The fuse εκρήγνυται, expelling vaporized metal, superheated gases, and ceramic shrapnel in all directions.

This isn’t theoretical. Field failures of under-rated fuses have caused panel fires, severe equipment damage, and injuries to nearby personnel. The National Electrical Code (NEC) Article 110.9 exists specifically to prevent this scenario, mandating that “equipment intended to interrupt current at fault levels shall have an interrupting rating sufficient for the nominal circuit voltage and the current that is available at the line terminals of the equipment.”

The High Rupturing Capacity Fuse Advantage

In contrast, a properly rated Ασφάλεια HRC with 200kA breaking capacity handling the same 65kA fault operates safely:

1. Element Melts: Calibrated silver-copper fuse element vaporizes at predetermined current levels.
2. Arc Initiation: High-temperature arc forms in controlled environment.
3. Sand Absorption: Quartz sand rapidly absorbs arc energy, fragmenting the arc into multiple smaller arcs and cooling the plasma.
4. Pressure Containment: Reinforced ceramic body withstands internal pressure from arc gases.
5. Safe Extinction: Arc extinguishes completely within milliseconds; circuit is safely opened with no external evidence beyond striker pin operation (if equipped).

The entire event—from fault initiation to complete arc extinction—occurs in 0.004 to 0.008 seconds (approximately one-quarter to one-half electrical cycle at 60Hz). To the external observer, the protection system simply “clicked” and safely isolated the fault.

Simplified Fault Current Estimation

Available fault current can be estimated using transformer data: ISC = (kVA × 1000) ÷ (√3 × Voltage × %Z) where %Z is transformer impedance expressed as a decimal. For a 1500 kVA transformer with 3.5% impedance feeding a 480V system: ISC = (1500 × 1000) ÷ (1.732 × 480 × 0.035) = 51,440 amperes. This represents the maximum fault current at the transformer secondary terminals; actual fault current at remote panels will be lower due to conductor impedance.

Professional short-circuit studies following IEEE 551-2006 or IEC 60909 standards account for all system impedances, motor contributions, and X/R ratios to provide accurate fault current values at each point in the distribution system.

Current Limiting Advantage: The Goalkeeper Strategy

When comparing protection methods for high fault-current installations, a fundamental question emerges: “Why not just use διακόπτες κυκλώματος with high interrupting ratings?”

The answer lies in physics and economics. Engineering a molded case circuit breaker (MCCB) to safely interrupt 100kA or 200kA requires massive reinforcement—enlarged arc chutes, heavy-duty contact systems, and complex arc-splitter assemblies. These modifications dramatically increase physical size, weight, and cost. A 200kA-rated circuit breaker in a 600A frame can cost $3,500-$5,500, while a 300kA-rated unit (if available at that amperage) might approach $8,000-$12,000.

Natural Current Limiting Performance

Fuses, by contrast, are inherently current-limiting devices. This characteristic provides profound advantages in high-fault-current applications.

Current limiting means the fuse operates so quickly during high-magnitude faults that the actual peak current (including the initial asymmetrical component) is significantly less than what would flow if the fuse were replaced by a solid conductor. A 200kA Class J fuse interrupting a 100kA prospective fault might limit the actual peak current to only 35kA-40kA and clear the fault in less than 0.004 seconds (one-quarter cycle).

This current limitation has two critical consequences:

1. Let-Through Energy Reduction: The I²t (amperes-squared-seconds) energy that downstream equipment experiences is drastically reduced—often by 90% or more compared to the full fault duration.
2. Mechanical Stress Mitigation: Electromagnetic forces in conductors and equipment (proportional to current squared) are minimized, preventing physical damage to busbars, cables, and connected devices.

Series Rating: The Goalkeeper Strategy

The current-limiting property enables an elegant and economical protection architecture called series rating (permitted under NEC 240.86). This strategy uses a high breaking capacity fuse as the “goalkeeper” to protect lower-rated downstream circuit breakers.

The Architecture:

1. Main Service Protection: Install a high breaking capacity fuse (200kA or 300kA Class J, RK1, or L) at the service entrance where available fault current is highest.
2. Current Limiting Action: During a downstream fault, the main fuse’s current-limiting action reduces the actual fault current magnitude and duration before it reaches branch circuit breakers.
3. Downstream Circuit Breakers: Specify lower-rated circuit breakers (65kA or 100kA) for branch circuits, knowing the main fuse limits fault energy to levels these breakers can safely handle.

Οικονομικός Αντίκτυπος:

Μέθοδος προστασίας	Main Device	Branch Protection	Total Cost (6-circuit panel)
Fully-Rated MCCBs	200kA MCCB, 600A: $4,500	200kA MCCBs, 100A (6×): $2,400/ea × 6 = $14,400	$18,900
Series-Rated with HBC Fuse	300kA Class J Fuse, 600A: $450	65kA MCCBs, 100A (6×): $800/ea × 6 = $4,800	$5,250
Εξοικονόμηση κόστους			$13,650 (72%)

The series-rated approach delivers identical protection with 70%+ cost reduction. The main fuse costs $450 vs. $4,500 for an equivalent-rated circuit breaker, while downstream breakers cost $800 vs. $2,400 each—all while providing faster clearing times and superior let-through energy characteristics.

Selective Coordination Considerations

While series-rated combinations offer economic advantages, engineers must understand the trade-offs. Series combinations cannot be selectively coordinated because the line-side fuse must operate in conjunction with the load-side circuit breaker during medium-to-high fault conditions.

For applications requiring selective coordination—such as health care facilities (NEC 517.17), emergency systems (NEC 700.27), legally required standby systems (NEC 701.18), elevator circuits (NEC 620.62), and critical operations power systems (NEC 708.54)—a fully-fused system with appropriately sized fuses at each level provides reliable selective coordination using published fuse selectivity ratios.

Comprehensive Comparison: Fuse Classes and Breaking Capacity

UL Fuse Class	Εκτίμηση Τάσης	Τρέχον εύρος	Standard Interrupting Rating	300kA Option Available	Κύρια Εφαρμογές	Βασικά πρότυπα
Class J	600V AC	1A – 600A	200kA	✓ Ναι	Motor control centers, industrial switchgear, transformer protection	UL 248-8, CSA C22.2 No. 248.8
Κλάση L	600V AC	601A – 6000A	200kA	✓ Ναι	Service entrance, large feeders, main distribution	UL 248-10, CSA C22.2 No. 248.10
Class RK1	250V/600V AC	1A – 600A	200kA	✓ Ναι	Industrial panels, motor circuits, high-performance applications	UL 248-12, CSA C22.2 No. 248.12
Class RK5	250V/600V AC	1A – 600A	200kA	Περιορισμένη	General industrial use, replacement for Class H	UL 248-12, CSA C22.2 No. 248.12
Class R (Generic)	250V/600V AC	1A – 600A	200kA	✓ Yes (RK1)	Standard industrial protection	UL 248-12, CSA C22.2 No. 248.12

Note: Class J and Class L fuses are current-limiting and cannot be interchanged with any other fuse class due to dimensional rejection features. Class R fuses include rejection features preventing installation in Class H fuse holders.

Available Fault Current by Facility Type

Τύπος εγκατάστασης	Typical Service Size	Typical Transformer	Estimated Available Fault Current	Recommended Minimum Breaking Capacity
Small Commercial (retail, office)	200A-400A, 208V/120V	75-150 kVA	10kA – 25kA	65kA (adequate margin)
Medium Commercial (warehouse, small manufacturing)	400A-800A, 480V/277V	300-750 kVA	25kA – 50kA	100kA – 200kA
Large Industrial (manufacturing, processing)	1200A-3000A, 480V/277V	1000-3000 kVA	10kA – 200kA	200kA – 300kA
Heavy Industrial (steel, chemical, data center)	3000A+, 480V or medium voltage	3000+ kVA	85kA – 150kA+	300kA (essential)

Fault current values are approximations at service entrance; actual values depend on transformer impedance, conductor length, and utility source strength. Professional short-circuit study recommended for critical applications.

Practical Selection Guidance for Facility Engineers

Selecting appropriate breaking capacity protection requires understanding both your current electrical system and potential future changes. The following guidance addresses common scenarios faced by facility engineers and procurement professionals.

Calculating Available Fault Current (Simplified Method)

For preliminary analysis, estimate three-phase bolted fault current at transformer secondary using: ISC = (kVA × 1000) ÷ (√3 × Voltage × %Z). For conductor runs from the transformer, adjust for impedance: ISC adjusted = ISC transformer × (Z transformer ÷ (Z transformer + Z conductor)).

Professional short-circuit studies should be performed by qualified engineers following IEEE 551-2006 for systems in commercial buildings or IEEE 242 for industrial and commercial power systems. These studies account for motor contribution (typically 4-6× motor full-load current), asymmetrical factors based on X/R ratios, and all impedances throughout the distribution system.

NEC Requirements: Articles 110.9 and 110.24

NEC 110.9 (Interrupting Rating) mandates that equipment intended to interrupt current at fault levels “shall have an interrupting rating at nominal circuit voltage sufficient for the current that is available at the line terminals of the equipment.” This requirement applies to all overcurrent protective devices—fuses, circuit breakers, and combinations thereof.

NEC 110.24 (Available Fault Current) requires service equipment in other than one- and two-family dwellings to be legibly marked in the field with the maximum available fault current. The marking must include the date the calculation was performed. This allows future inspectors, electricians, and engineers to verify that installed protection devices have adequate interrupting ratings.

Industrial control panels (NEC 409.22), motor control centers (NEC 430.99), switchboards and panelboards (NEC 408.6), and air conditioning equipment (NEC 440.10) all have specific requirements for fault current documentation and short-circuit current ratings.

When to Specify 200kA vs. 300kA

Specify 200kA breaking capacity when:

• Available fault current is reliably below 125kA (providing 60% safety margin)
• Upstream utility infrastructure is stable with no planned upgrades
• Facility electrical system is mature with no expansion plans
• Cost optimization is critical and 200kA provides adequate margin

Specify 300kA breaking capacity when:

• Available fault current exceeds 125kA or approaches 200kA
• Service is fed from low-impedance source (large transformer, short conductor runs)
• Utility has announced or implemented grid modernization in your area
• Facility is in growing industrial park with increasing power density
• Future expansion or service upgrades are anticipated within 10-20 year horizon
• Maximum safety margin is desired for critical or high-risk facilities

Procurement Red Flags: Identifying Inadequate Protection

Warning signs of inadequate breaking capacity specifications:

1. Undefined Interrupting Rating: Supplier quotes “fuse, 100A, 600V” without specifying interrupting rating or fuse class
2. Unusually Low Pricing: Generic fuses offered at 30%-40% below branded Class J/L/R pricing may have 10kA-50kA ratings
3. Vague Standards Compliance: Claims of “industrial grade” without referencing UL 248 series standards
4. Class H Substitution: Offering Class H fuses (10kA typical interrupting rating) for industrial applications
5. Missing Current-Limiting Certification: Fuses not marked “Current Limiting” per UL standards lack critical let-through energy control

Best practices for procurement specifications:

• Always specify: Fuse Class (J, L, RK1, etc.), Ampere Rating, Voltage Rating, and Interrupting Rating
• Example: “Class RK1 fuse, 100A, 600V AC, 300kA interrupting rating, UL 248-12, time-delay”
• Require third-party certification documentation (UL file numbers)
• Verify dimensional specifications match existing fuse holders (prevent accidental downgrades)
• Include “or approved equal” language with explicit performance requirements

VIOX High Breaking Capacity Fuse Solutions

VIOX Electric manufactures comprehensive lines of high breaking capacity fuses for industrial, commercial, and critical infrastructure applications:

VIOX Class J Current-Limiting Fuses

• 600V AC rated, 1A through 600A
• 200kA or 300kA interrupting rating options
• Time-delay characteristics for motor and transformer inrush tolerance
• Compact 13/16″ × 1-3/4″ to 3″ × 9-1/16″ dimensions depending on amperage
• Applications: Motor control centers, industrial switchgear, transformer secondaries

VIOX Class L High-Amperage Fuses

• 600V AC rated, 601A through 6000A
• 200kA or 300kA interrupting rating
• Current-limiting with exceptional I²t let-through characteristics
• Applications: Service entrance protection, main distribution, large feeder circuits

VIOX Class RK1 Dual-Element Fuses

• 250V/600V AC rated, 1A through 600A
• 300kA interrupting rating
• Superior time-delay performance (holds 500% rated current minimum 10 seconds)
• Applications: Motor branch circuits, combination motor controllers, high-performance protection where selective coordination with upstream devices is required

All VIOX fuses comply with UL 248 series standards and carry CSA certification for North American markets. Products are tested to full-rated interrupting capacity and certified for dimensional interchangeability with existing UL-classified fuse systems.

Συχνές Ερωτήσεις

What is breaking capacity and why does it matter?

Breaking capacity (also called interrupting rating or rupturing capacity) is the maximum fault current that a fuse can safely interrupt without rupture, fire, or dangerous arc propagation. It matters because if fault current exceeds the breaking capacity, the fuse can explode instead of safely opening the circuit, creating fire hazards and equipment damage. Breaking capacity must exceed the available fault current at the installation point with adequate safety margin.

How do I know what breaking capacity I need for my facility?

Determine the available fault current at your service entrance through professional short-circuit analysis following IEEE 551-2006 standards. As a simplified estimate, calculate transformer secondary fault current using: ISC = (kVA × 1000) ÷ (√3 × Voltage × %Z). Select fuses with interrupting ratings at least 25% higher than calculated fault current. For industrial facilities with 50kA+ available fault current, specify 200kA minimum; for 125kA+ or high-growth areas, specify 300kA.

What’s the difference between interrupting rating and short-circuit current rating (SCCR)?

Interrupting rating (IR) applies to individual overcurrent protective devices (fuses, circuit breakers) and defines the maximum current they can safely interrupt. Short-circuit current rating (SCCR) applies to complete assemblies (motor control centers, industrial control panels, switchboards) and defines the maximum fault current the entire assembly can withstand when protected by specified overcurrent devices. Equipment SCCR must meet or exceed available fault current per NEC 110.9.

Can I use a 200kA fuse if my fault current is only 50kA?

Yes—this is actually recommended practice. Using a higher-rated fuse than minimum requirements provides safety margin for future utility changes, system modifications, or calculation uncertainties. The 200kA fuse will operate identically to a 100kA fuse under normal conditions and fault currents up to 100kA; the higher rating simply ensures safe operation if fault currents increase. There is no penalty for over-specifying breaking capacity (unlike over-sizing ampere rating, which delays overcurrent protection).

Why are 300kA fuses not significantly more expensive than 200kA fuses?

Upgrading fuse breaking capacity from 200kA to 300kA typically requires minimal design changes—primarily improved arc-quenching materials and reinforced ceramic bodies. These modifications add 10%-20% to manufacturing cost, translating to modest price increases ($50-$150 depending on ampere rating). In contrast, upgrading circuit breakers from 100kA to 200kA requires substantial mechanical reinforcement, larger arc chutes, and heavy-duty components, often doubling or tripling the price. This cost difference makes high breaking capacity fuses extraordinarily economical for high-fault-current protection.

What happens if I install a fuse with insufficient breaking capacity?

During a fault exceeding the fuse’s interrupting rating, the arc energy generated exceeds the fuse’s containment capability. The ceramic body ruptures under internal pressure, expelling vaporized metal, superheated gases, and ceramic fragments. This creates secondary short circuits to adjacent phases or ground, causes panel fires, damages surrounding equipment, and poses severe injury risk to nearby personnel. Post-failure investigation often reveals extensive collateral damage costing 10x-100x more than the cost difference between adequate and inadequate fuses.

How often should breaking capacity be re-evaluated?

Perform fault current analysis whenever: (1) Utility notifies you of transformer upgrades or service changes, (2) Facility adds significant loads requiring service upgrade, (3) New equipment is installed changing fault current contribution (large motors, generators, UPS systems), (4) Major renovations modify distribution architecture, or (5) At minimum every 5-7 years as part of preventive maintenance program. NEC 110.24 requires field marking with fault current calculation date, enabling tracking of when re-evaluation is needed.

Are higher breaking capacity fuses more sensitive or prone to nuisance tripping?

No. Breaking capacity affects only the fuse’s ability to safely interrupt high fault currents—it does not affect normal operating characteristics, time-current curves, or sensitivity to overloads. A 300kA Class RK1 100A time-delay fuse will have identical operating characteristics to a 200kA Class RK1 100A time-delay fuse under all normal and overload conditions. The difference becomes relevant only during short-circuit events approaching or exceeding 200kA, where the 300kA fuse maintains safe operation while the 200kA fuse approaches its design limits.

Technical Standards and Compliance References

Understanding applicable standards ensures proper fuse selection, installation, and compliance with regulatory requirements:

UL 248 Series: Low-Voltage Fuses

• UL 248-8 (Class J Fuses): Covers current-limiting fuses rated 600A or less and 600V AC, with standard 200kA interrupting rating and optional 300kA rating. Defines dimensional standards preventing interchangeability with other classes, time-delay testing requirements (minimum 10 seconds at 500% rated current), and let-through energy limits.
• UL 248-10 (Class L Fuses): Applies to current-limiting fuses rated 601A through 6000A and 600V AC. Specifies standard 200kA interrupting rating with 300kA options available. Covers large-amperage protection for service entrances and main feeders with dimensional standards for 800A through 6000A frame sizes.
• UL 248-12 (Class R Fuses): Defines requirements for Class R fuses (including RK1 and RK5) rated 600A or less at 250V or 600V AC. Class RK1 fuses have superior current-limiting characteristics and 200kA or 300kA interrupting ratings. Includes rejection features preventing installation in Class H holders.

National Electrical Code (NFPA 70)

• NEC 110.9 (Interrupting Rating): Mandates that equipment intended to break current at fault levels shall have interrupting rating sufficient for voltage and available current. Fundamental requirement ensuring all overcurrent devices can safely handle prospective fault currents.
• NEC 110.24 (Available Fault Current): Requires service equipment marking with maximum available fault current and calculation date for other than dwelling units. Enables verification of adequate protection device ratings.
• NEC 240.86 (Series Ratings): Permits series-rated combinations of fuses and circuit breakers where tested and marked on equipment, providing economic alternative to fully-rated systems where selective coordination is not required.

Πρότυπα IEEE

• IEEE 551-2006 (Calculating Short-Circuit Currents): Provides recommended practice for calculating short-circuit currents in industrial and commercial power systems, including transformer contribution, motor contribution, conductor impedance, and asymmetrical considerations. Essential reference for professional fault current analysis.

CSA Standards (Canadian Equivalents)

• CSA C22.2 No. 248.8 (Class J), CSA C22.2 No. 248.10 (Class L), CSA C22.2 No. 248.12 (Class R): Harmonized tri-national standards (US/Canada/Mexico) ensuring product interchangeability and consistent performance requirements across North American markets.

Conclusion: Engineering Response to Grid Reality

The electrical industry’s quiet transition from 200kA to 300kA interrupting ratings isn’t a marketing exercise—it’s an engineering response to measurable changes in power distribution infrastructure. Available fault currents at industrial service entrances are rising due to utility grid modernization, transformer replacements with lower impedance units, and increased power density in industrial facilities.

For facility engineers, procurement managers, and electrical contractors, the implications are clear: breaking capacity specifications that were adequate 15-20 years ago may be marginal or inadequate today. The cost differential between 200kA and 300kA fuses—typically 10%-20%—represents trivial insurance against catastrophic protection system failure.

High breaking capacity fuses provide the most economical solution for high-fault-current protection, combining superior interrupting performance with current-limiting characteristics that protect downstream equipment. The series-rating strategy, using a high breaking capacity fuse as the “goalkeeper” to protect lower-rated downstream circuit breakers, can reduce protection system costs by 70% while maintaining or improving safety performance compared to fully-rated circuit breaker systems.

The invisible shield protecting your facility from short-circuit disasters isn’t the largest component or the most expensive—it’s the appropriately rated fuse that will never be noticed during normal operation but performs flawlessly during the catastrophic fault that could destroy equipment and endanger personnel.

Ready to verify your facility’s protection is adequate? VIOX Electric’s technical team provides complimentary fault current analysis and protection system reviews for industrial and commercial facilities. Our application engineers can evaluate your existing system, recommend appropriate breaking capacity upgrades, and specify complete protection solutions meeting NEC requirements and industry best practices.

Contact VIOX Electric today for technical consultation on high breaking capacity fuse selection, fault current analysis, or complete protection system design. Because when 200,000 amperes of fault current tests your facility’s defenses, you want to be certain your invisible shield is strong enough.