Free Tool · IEC 60364-4-43

Cable Discrimination & Protective Device Coordination

Verify that upstream protective devices allow cables to carry fault current without tripping first. Covers IEC 60364-4-43 §434 cable thermal withstand, IEC 60898 MCB curves B/C/D, IEC 60947-2 MCCB/ACB (Ir/Im/Ii), and IEC 60269 gG fuse selectivity.

System Parameters

Short-Circuit Current I_sc (kA)

Min. Fault Current at Downstream (kA)

Upstream Device Type

Upstream Ir / I_n (A)

Upstream Im — Short-Time Delay (A)

Upstream Ii — Instantaneous (A)

Upstream Icw — Short-Time Withstand (A)

Upstream Ir / I_n (A)

Upstream MCB Curve

Upstream Ir / I_n (A)

Upstream Fuse Class

Downstream Device Type

Downstream Ir / I_n (A)

Downstream MCB Curve

Downstream Ir / I_n (A)

Downstream Im — Short-Time Delay (A)

Downstream Ii — Instantaneous (A)

Downstream Ir / I_n (A)

Downstream Fuse Class

Cable Cross-Section S (mm²)

Conductor Material

Insulation Type

Max. Conductor Temperature (°C)

Fault Clearing Time t (s) Default 0.4s (IEC 60364-4-43 Table A)

⚡

Enter system parameters and click Calculate

Discrimination Results

—

mm²

Cable Thermal

—

Discrimination

—

mm²

S_min

—

k factor

—

Clearing time

—

Selectivity a

Step-by-Step Checks

#	Check	Input	Result	Status

S_min = I_sc · √t / k (IEC 60364-4-43 §434). k=143 for Cu/PVC, 143 for Cu/XLPE, 90 for Al/PVC, 90 for Al/XLPE, 76 for Cu cold-forming. Default t = 0.4s (Table A of IEC 60364-4-43).

Related tools

Standards: IEC 60364-4-43 §434, IEC 60898, IEC 60947-2, IEC 60269