SCCR Calculator
Screen whether equipment SCCR / kAIC meets available fault current at the bus. Example: 18 kA available vs 22 kA panel mark → adequate. Use the calculator below—not coordination, arc-flash, or utility sign-off.
Quick SCCR Calculator
Quick: compare kA available vs kAIC directly. Advanced: estimate Isc from transformer kVA and %Z.
About this calculator
Verifies that marked SCCR / kAIC is not exceeded by available fault current before OCPD and conductor screening. Part of the protection calculators hub workflow with breaker sizing and coordination planning.
Calculation Results
Adequate SCCR — 22 kA vs 18 kA available (default example).
Engineering disclaimer
Screening only. Utility fault contribution, motor contribution, X/R ratio, and series ratings are not modeled—confirm with a qualified engineer and manufacturer data.
Common SCCR / kAIC marks (reference)
| Mark (kA) | Typical context |
|---|---|
| 10 / 14 | Small panels, remote branches |
| 18 / 22 / 25 | Industrial MCC / panelboards |
| 35 / 42 / 47 | Higher fault industrial buses |
| 65 / 85 / 100 | Large switchgear, close-in utility |
SCCR formula (screening)
Direct check: Equipment SCCR (kA) ≥ Available Isc (kA) × (1 + Margin%)
Transformer estimate: IFL = kVA × 1000 ÷ (√3 × V) for 3-phase; Isc ≈ IFL ÷ (%Z ÷ 100)
Guides: Short-circuit planning · Coordination & SCCR
Worked example
- 1000 kVA, 5%Z, 480 V 3-phase: IFL ≈ 1203 A → Isc ≈ 24.1 kA. A 22 kA panel is insufficient; select 25 kA or higher listed assembly.
- Direct compare: Utility study shows 18 kA at MCC → a 22 kAIC bucket is adequate with headroom.
Frequently Asked Questions
What is SCCR vs kAIC?
Both describe fault-withstand or interrupt rating in kA. Compare the bus Isc to the marked SCCR/kAIC on the assembly or device.
How do I estimate available fault current from a transformer?
Isc ≈ IFL ÷ (%Z/100). Use nameplate %Z and secondary voltage—utility and motor contribution add on top.
Is this a coordination or arc-flash study?
No—pass/fail screening only. Coordination curves and incident energy need project deliverables.
What SCCR values are common on industrial panels?
10, 14, 18, 22, 25, 35, 42, 47, 65, 85, 100 kA marks appear on listed assemblies—use the specific SKU listing.
What is the next step after SCCR screening?
Size breakers, validate cable ampacity, and read the coordination guide before procurement.