Free tool
Cable Sizing · Voltage Drop · Fuse & Breaker Selection
Undersized cables overheat. Oversized cables waste money and fail inspections. This calculator gives you the correct cable cross-section, verifies your voltage drop is within standard limits, and selects the right overcurrent protection device — all based on IEC 60364-5-52 or NEC 310.16, your choice.
How to use this calculator
Step 01
Choose your wiring standard
Select IEC 60364-5-52 (international/Nigeria) or NEC 310.16 (USA). All tables, correction factors, and rules switch automatically.
Step 02
Size the cable
Enter your load current, installation method, conductor material, insulation type, ambient temperature, and grouping. Get the minimum cable size with full derating applied.
Step 03
Verify voltage drop
Take the cable size from Step 02, enter your run length and system voltage, and confirm the drop is within the recommended limit for your circuit type.
Step 04
Select fuse or breaker
Enter your design current and the derated ampacity from Step 02. The calculator finds the correct OCPD rating that satisfies the Ib ≤ In ≤ Iz coordination rule.
Cable & Electrical Calculator
IEC 60364-5-52 · NEC 310.16 · Three precision tools
Eneronix
Your Energy, Our Precision
Wiring standard
1 Cable Sizing
2 Voltage Drop
3 Fuse / Breaker
40°C
1
Engineering estimates only. Results are based on IEC 60364-5-52:2009 Ed.3 and NEC 2023 Table 310.16. Real installations must be verified by a qualified electrical engineer and must comply with local wiring regulations. Derating factors are from published standard tables — site-specific conditions may require more conservative sizing. © Eneronix — eneronix.com
Understanding your results
Derated ampacity (Iz)
The actual current-carrying capacity of your cable after applying temperature and grouping correction factors. This is what your cable can safely carry in its installed condition — always higher than Ib.
Voltage drop %
IEC recommends ≤4% for final circuits, ≤5% absolute maximum. NEC recommends ≤3% for branch circuits. Sensitive loads like inverters and VFDs perform best below 3%. Excessive drop causes heat, efficiency loss, and equipment faults.
Coordination rule: Ib ≤ In ≤ Iz
Your overcurrent protection device rating (In) must be at least as large as the load current (Ib) and no larger than the cable’s derated capacity (Iz). This ensures the device protects the cable under all fault conditions.
IEC vs NEC standard
Nigeria uses IEC standards. Use IEC 60364-5-52 for all local installations. NEC is the US standard — useful if you are sizing equipment that was designed or manufactured to American specifications.