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In electrical engineering and fire protection, breakthrough voltage (also called dielectric breakdown voltage) is the minimum voltage at which an insulating medium (gas, liquid, or solid) becomes conductive and allows an electric arc to pass through.
In the context of fixed gaseous fire suppression systems, this means:
Under normal conditions, gaseous agents act as electrical insulators and do not conduct electricity.
However, when the applied voltage exceeds the breakthrough voltage, the gas can no longer resist ionization, and an electrical discharge (arc) may occur across the medium.
This property is crucial because most gaseous fire suppression systems are used in electrical rooms, data centers, and control facilities, where energized equipment may still be live during a fire.
Electrical Safety – The agent must not create conductive paths that could worsen electrical faults or cause arc flash.
Agent Selection – Systems protecting high-voltage switchgear or substations require gases with high dielectric strength.
Standards Compliance – NFPA 2001 (Clean Agent Systems), NFPA 12 (CO₂ Systems), and ISO 14520 specify the suitability of agents for energized equipment.
| Agent | Composition | Dielectric Strength / Breakthrough Voltage | Suitability for Electrical Hazards |
|---|---|---|---|
| CO₂ (Carbon Dioxide) | Stored as liquid, discharged as gas | ~7–10 kV/cm (slightly above air) | Safe for low/medium voltage, but not recommended above ~25–30 kV |
| FM-200 (HFC-227ea) | Hydrofluorocarbon | ~90 kV/cm (≈ 6–7× air) | Very high dielectric strength → preferred for energized IT & electrical rooms |
| Novec 1230 (FK-5-1-12) | Fluoroketone | ~90–100 kV/cm | Excellent insulating properties, safe for high-voltage electronics |
| Inergen (IG-541) | N₂ (52%), Ar (40%), CO₂ (8%) | Comparable to air (~30 kV/cm) | Safe up to medium voltages; not ideal for very high kV switchgear |
| Argonite (IG-55) | 50% Argon + 50% Nitrogen | ~30 kV/cm | Similar to Inergen |
| IG-100 (Nitrogen) | 100% Nitrogen | ~30 kV/cm | Comparable to air |
Note: Values are approximate and depend on temperature, humidity, pressure, and electrode spacing.
A CO₂ system in a 30 kV substation may not prevent arc propagation because its dielectric strength is too close to that of air.
A Novec 1230 or FM-200 system is safer, as they provide significantly higher insulation against electrical breakdown.
NFPA 2001 (Clean Agent Fire Extinguishing Systems): Recognizes clean agents like FM-200 and Novec 1230 as safe for energized equipment because of their high dielectric strength.
NFPA 12 (CO₂ Systems): Permits CO₂ use for electrical hazards but with caution at higher voltages (>25–30 kV).
EN 15004 (European equivalent of ISO 14520): Specifies dielectric testing requirements for clean agents used in IT and electrical environments.
Breakthrough voltage is the critical factor determining whether a gaseous fire suppression agent can be safely used around energized electrical equipment.
CO₂ and inert gases: Suitable for low to medium voltage equipment.
FM-200 and Novec 1230: Safe and recommended for high-voltage and sensitive electronic equipment due to their superior dielectric strength.
👉 Choosing the right suppression agent is not just about fire control — it’s also about electrical safety.
📩 To design or audit a safe gaseous fire suppression system for your facility, contact us at: agnirakshaniti@gmail.com
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