Was ist der Kabelquerschnitt?
Cable cross-section is the area of the conductive metal part of the cable, expressed in mm². A larger cross-section reduces resistance and voltage drop but increases cost and installation space.
The value must be selected according to the real operating conditions, not by habit or a single current value.
Warum muss der Kabelquerschnitt richtig gewählt werden?
Undersized cables overheat and create voltage drop, while oversized cables increase cost and complicate panel wiring. Correct sizing balances safety, performance and economy.
Einflussfaktoren auf den Kabelquerschnitt
Strom
Continuous load current and starting current are key inputs.
Length
Longer lines increase resistance and voltage drop.
Voltage drop
The load-side voltage must remain within acceptable limits.
Ambient temperature
High temperature reduces current-carrying capacity.
Installation method
Tray, conduit, buried or open-air installation changes cooling.
Cable type
Insulation, conductor material and number of cores matter.
Grouping
Cables installed together heat each other and need derating.
Protection device
The breaker or fuse must protect the cable properly.
Bedeutung des Spannungsfalls
Voltage drop is especially important in long feeders, motor circuits and sensitive equipment.
| Condition | Possible effect | Engineering response |
|---|---|---|
| Long cable run | Low voltage at the load | Increase cross-section or revise supply point |
| Motor feeder | Hard starting and overheating | Check starting current and allowed drop |
| Lighting circuit | Reduced light level | Split circuits or increase section |
| Sensitive load | Unstable operation | Use tighter voltage-drop limits |
Risiken eines falschen Kabelquerschnitts
Overheating
Insulation ages faster and fire risk increases.
High voltage drop
Motors and devices may operate poorly.
Energy loss
Higher resistance means higher operating cost.
Protection mismatch
Fuses or breakers may not protect the cable correctly.
Difficult installation
Oversized cables can complicate terminals and routing.
Vergleich von Kupfer- und Aluminiumkabeln
Copper is compact and highly conductive; aluminium is lighter and can be economical in large sizes.
| Kriterium | Copper | Aluminium |
|---|---|---|
| Conductivity | Higher | Lower; larger section usually needed |
| Weight | Heavier | Lighter |
| Connection | Common and practical | Needs suitable lugs and tightening practice |
| Cost | Usually higher | Often economical for large feeders |
| Typical use | Panels, machines, compact wiring | Long feeders and large distribution lines |
Häufige Querschnitte und Anwendungen
The values below are only indicative. Strom capacity changes with installation method, ambient temperature, cable type, number of loaded cores and grouping.
| Section | Approx. current capacity | Typical use |
|---|---|---|
| 1.5 mm² | 10 - 16 A | Lighting and auxiliary circuits |
| 2.5 mm² | 16 - 25 A | Socket and small power circuits |
| 4 mm² | 25 - 32 A | Small motors and sub-feeders |
| 6 mm² | 32 - 40 A | Medium power circuits |
| 10 mm² | 45 - 63 A | Machine feeders |
| 16 mm² | 63 - 85 A | Sub-panels and motor feeders |
| 25 mm² | 85 - 115 A | Distribution feeders |
| 35 mm² | 110 - 145 A | Main or sub feeders |
| 50 mm² | 140 - 180 A | High-current distribution |
Praktische Empfehlungen
Start with the load
Clarify current, simultaneity and future additions.
Check the distance
A section sufficient for a short run may fail by voltage drop in a long run.
Define installation
Tray, conduit, buried and panel wiring have different cooling.
Coordinate protection
The protective device must match the cable rating.
Leave service space
Plan bending radius, terminals and labels.
Verify by standards
Compare the result with IEC/TS tables and manufacturer data.
IEC- und TS-Normen
Standards and manufacturer data must be used for final verification.
| Reference | Scope |
|---|---|
| IEC 60364 | Low-voltage electrical installations and cable selection rules |
| TS HD 60364 | National implementation for low-voltage installations |
| IEC 60228 | Conductor classes and conductor properties |
| Manufacturer catalogues | Strom ratings by cable type and installation method |
Fazit
Cable sizing must consider current capacity, voltage drop, installation conditions, ambient temperature, cable material and protective devices together. Calculations should be checked against relevant standards and manufacturer tables.
Kabelquerschnitt berechnen
Kabelquerschnitt berechnen
Die Auswahl des Kabelquerschnitts ist entscheidend für Sicherheit und Energieeffizienz. Der richtige Querschnitt reduziert Erwärmung, Spannungsfall, Verluste und Ausfallrisiken.
FAQ
Can cable size be selected only by current?
No. Distance, voltage drop, installation method, temperature, cable type and grouping must also be considered.
Why is voltage drop important?
It can reduce equipment performance, cause motor problems and increase energy loss.
Copper or aluminium?
Copper is compact and conductive; aluminium is lighter and economical for large feeders.
What data is needed?
Strom, voltage, phase, length, allowed voltage drop, conductor material, installation method, temperature and grouping.