Every cable is a heater you are trying not to use.
Pick a cable too thin and it cooks. Pick one too long and the motor will not start. Pick the wrong breaker and a fault leaves metal live. Cable sizing balances these, using rules that differ between Europe (IEC, VDE) and the US (NEC). Learn both here from zero, with the German words your spec uses. Every answer explains itself; wrong answers come back until they stick.
What a cable sizing tool does, in 8 steps
The steps behind "DOL-Motor 400 V, 55 kW, 150 m, Verlegeart C". The Toolbox runs all eight, EU and US side by side.
- Describe the loadType, power, voltage, start method, cable length. (German: Verbraucher)
- Design current IbFrom power, voltage, cos φ, efficiency. US: table FLC × 125%.
- Pick the protectionFuse or breaker In ≥ Ib; for motors, an overload relay too. (ÜSE)
- Correct for conditionsInstallation method, ambient, grouping. (Verlegeart, Häufung)
- Size for heatSmallest cable with Iz ≥ what protection demands: In ≤ Iz, I₂ ≤ 1.45 Iz.
- Check voltage drop3%/5% running; motor start dip. Long runs grow here. (Spannungsfall)
- Check the fault loopEarth fault current must trip the device in 0.4 s or 5 s. (Schleifenimpedanz)
- Check short-circuit heatk²S² ≥ I²t for the smallest conductor, usually the PE.
Mastery by domain
Line = 80% goal. Click a domain to practice it.How to use this
- Study a domain's notes. Start with Basics, then Ampacity, Protection and Volt drop. "EU vs US" sums up the differences on one page.
- Practice daily. Each question carries a tag: EU US EU + US. Filter by region if you want one side only.
- Drill the calculations until currents, derating, voltage drop and loop impedance feel automatic.
- Toolbox: type a load in German or English, then watch both rulebooks size it step by step. Change one input and see which check bites.
For learning only, not for design. Tables are copper-only training extracts from IEC 60364-5-52 and NEC 2023; national editions (DIN VDE 0298-4, VDE 0100-520 Beiblatt 2) and makers' data differ. Progress stays in this browser.
Keys: 1–4 to answer, Enter for next.
Have a calculator ready. Keys: 1–4, Enter.
Skills check
A timed mix of every domain, about a quarter calculations. No feedback until you submit. You can flag questions and jump around.
The goal is 80%, this app's own bar for "I can follow a cable sizing discussion".
History
1 · From words to inputs
Your spec imagines an AI that reads "DOL-Motor 400 V, 55 kW, 150 m Kabel, Verlegeart C" and fills in the inputs. This box does a simple version with pattern matching, in German or English. It shows what has to be extracted and what falls back to a default.