Question 1

What is Ohm's Law and how do I calculate it?

Accepted Answer

Ohm's Law states V = I × R, where V is voltage (volts), I is current (amperes), and R is resistance (ohms). Power P = V × I = I² × R = V²/R. Our Ohm's Law calculator solves all four variables automatically.

Question 2

How do I calculate voltage drop in a cable?

Accepted Answer

Voltage drop = I × R × L × 2 (for single-phase) or I × R × L × √3 (for three-phase), where I is load current in amps, R is cable resistance in Ω/km, and L is cable length in km. Per IEC 60364, voltage drop should not exceed 3% for lighting or 5% for power circuits.

Question 3

What is power factor correction and why does it matter?

Accepted Answer

Power factor (PF) is the ratio of real power (kW) to apparent power (kVA). A PF below 0.95 incurs utility penalties. To correct PF from PF1 to PF2: Qc (kVAR) = P × (tan(cos⁻¹(PF1)) − tan(cos⁻¹(PF2))), where P is load in kW.

Question 4

How do you calculate cable size for a 3-phase circuit?

Accepted Answer

Cable sizing per IEC 60364-5-52 requires: 1) Calculate design current Ib. 2) Select cable with Iz ≥ Ib after applying derating factors (temperature, grouping, burial). 3) Verify voltage drop ≤ 5%. 4) Check short-circuit thermal withstand. Use our Cable Sizing Calculator for instant IEC-compliant results.

Question 5

What is short circuit current calculation per IEC 60909?

Accepted Answer

Per IEC 60909, maximum prospective short-circuit current Ik" = U/(√3 × Zk), where U is the nominal voltage and Zk is the total impedance at the fault point including source, transformer, and cable impedances. Our short-circuit calculator handles all IEC 60909 calculations automatically.

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