Ampere Interrupting Capacity Calculator: Find Your AIC Rating

by

⚡ Ampere Interrupting Capacity Calculator

Calculate the required AIC rating for circuit breakers based on system voltage, impedance, and available fault current

📌 Quick Presets
🔧 System Parameters
✅ AIC Calculation Results
📊 Standard AIC Ratings Reference
10 kA
Residential Typical
22 kA
Light Commercial
42 kA
Commercial Standard
65 kA
Industrial Standard
100 kA
Heavy Industrial
150 kA
Utility / HV Service
200 kA
Maximum Standard AIC
≥AIC
NEC 110.9 Minimum
📋 Available Fault Current by System Type
System Type Voltage Typical kVA Typical AFC (kA) Min AIC Needed
Residential Service120/240V25–100 kVA3–10 kA10,000 A
Light Commercial120/208V 3ϖ75–300 kVA10–22 kA22,000 A
Commercial Office277/480V 3ϖ300–750 kVA22–42 kA42,000 A
Large Commercial480V 3ϖ750–1500 kVA42–65 kA65,000 A
Industrial Plant480V 3ϖ1500–3000 kVA65–100 kA100,000 A
Heavy Industrial480V 3ϖ3000+ kVA100–200 kA200,000 A
Data Center480V 3ϖ1000–5000 kVA50–150 kA100,000 A
📐 Transformer Impedance vs. Fault Current
Transformer kVA %Z (Typical) Voltage Full-Load Amps Short-Circuit kA
25 kVA2.0–3.5%240V 1ϕ104 A3.0–5.2 kA
75 kVA2.0–4.0%208V 3ϕ208 A5.2–10.4 kA
150 kVA3.5–5.75%208V 3ϕ416 A7.2–11.9 kA
225 kVA3.5–5.75%480V 3ϕ271 A4.7–7.7 kA
500 kVA4.5–5.75%480V 3ϕ601 A10.4–13.4 kA
1000 kVA5.0–5.75%480V 3ϕ1203 A20.9–24.1 kA
2000 kVA5.75%480V 3ϕ2406 A41.8 kA
3000 kVA5.75%480V 3ϕ3608 A62.8 kA
🔌 Standard AIC Ratings & NEC Compliance
Standard AIC Rating Breaker Class Typical Application NEC Compliance
5,000 A (5 kA)Molded CaseLow-fault residential110.9, 240.86
10,000 A (10 kA)Molded CaseStandard residential110.9, 230.65
14,000 A (14 kA)Molded CaseResidential/light comm.110.9
22,000 A (22 kA)Molded CaseLight commercial110.9, 408.6
42,000 A (42 kA)Molded CaseCommercial110.9
65,000 A (65 kA)Molded Case / ICCBLarge commercial/industrial110.9
100,000 A (100 kA)Insulated Case / LVPCBHeavy industrial110.9
200,000 A (200 kA)LV Power CBUtility service entrance110.9
📏 Cable Impedance Reference (Resistance Ω/ft at 75°C)
AWG / Size Metric (mm²) Resistance (Ω/1000 ft) Ampacity (75°C)
#14 AWG2.5 mm²3.14 Ω15 A
#12 AWG4 mm²1.98 Ω20 A
#10 AWG6 mm²1.24 Ω30 A
#8 AWG10 mm²0.778 Ω50 A
#6 AWG16 mm²0.491 Ω65 A
#4 AWG25 mm²0.308 Ω85 A
#2 AWG35 mm²0.194 Ω115 A
#1/0 AWG50 mm²0.122 Ω150 A
#2/0 AWG70 mm²0.0967 Ω175 A
#3/0 AWG95 mm²0.0766 Ω200 A
#4/0 AWG120 mm²0.0608 Ω230 A
350 kcmil185 mm²0.0370 Ω310 A
500 kcmil240 mm²0.0258 Ω380 A
⚡ NEC Code Requirement (110.9): Circuit breakers and fuses must have an interrupting rating sufficient for the maximum available fault current at their terminals. Never install a breaker with an AIC rating lower than the available fault current at that point in the system.
📐 How to Estimate Available Fault Current: Short-circuit current (kA) = Transformer kVA ÷ (√3 × Voltage × %Z) for three-phase, or kVA ÷ (Voltage × %Z) for single phase. Always add cable impedance and request utility fault current data from your power provider for the most accurate calculation.

The capacity for suspend amperojn, or AIC, as one commonly calls it, commonly appear in talks about fuses and interrompiloj of circuits. One also hears it call rating of interference of amperoj or similarly. Sometimes it shows up in technical details as available capacity for suspend.

No matter what label one lays on it the notion stays the same.

What AIC Means for Circuit Breakers

Here what AIC truly wants to say: it points to the biggest flow during fault, that interrompilo of circuit or fuse can close without eksplodado, without trigger fire or without fail badly. Picture that situation. Interrompilo of circuit can have normal rating of 200 amperoj.

It will not turn unless the flow passes that limit. Even so that same interrompilo of 200 amperoj can have AIC of 35 000 amperoj. If fault causes 35 000 amperojn flowing through it, the interrompilo quickly take it under control and close itself safely.

The basic rating of AIC, that one meets most commonly, are 10 000 amperoj, short form 10 KAIC. Here the limit, where the device escapes to twist in internal arkŝovilo, what clearly could trigger electrical fire in body. When one talks about ratnigs above 1 000 amperoj, one uses kAIC.

Like this interrompilo of 10 kA can halt until 10 000 amperoj, while interrompilo of 30 kA handles everything until 30 000 amperoj.

At the core, the rating of AIC tells you, what maximum flow the protective device against too much flow can safely last and suspend. The rating of interference of interrompilo is the upper limit for the amperoj, that it can handle during fault state. Big industrial interrompiloj of circuits usually come with rating of KAIC, that shows, for what size of circuit they answer.

Different lines of products range a lot… Some reaches only 500 amperojn, while others go until around 50 000 amperoj.

Here where it becomes interesting: the voltage changes everything. Interrompilo, that can suspend 50 000 amperojn in 208 volts, only can handle 10 000 amperojn in 600 volts. Assume 60-amperan interrompiloon working in 600 volts, and its rating of interference falls too 18 000 amperoj.

Drop it to 480 volts, and sharply the rating jumps to 25 000 amperoj.

AIC truly is only one part of the puzzle when one sizes interrompilojn of circuit. The two other factors, that matter to consider, is the rating of continuous flow and the rating of voltage. Now, AIC commonly confuses with SCCR; rating of flow during short circuit, but they are entirely different.

Both can have rating of 10 kA, but AIC wants to say, that the interrompilo will open the circuit during faults until that level without damage. SCCR wants to say, that the whole unit can last that huge flow through it without damage.

For interrompilo of 10 kA, the main notion is ensure, that it will open the circuit during fault without eksplodado or without internal damage. Any gear, that uses combined ratings in series, must be marked clearly on the place by means oflabel, that shows the rating of the system in amperoj.

Ampere Interrupting Capacity Calculator: Find Your AIC Rating

Leave a Comment