How to choose a cable?
When choosing a cable, evaluate the intended use, cross-section, voltage drop and installation conditions together. Short answers to selection questions.
Where do you start when choosing a cable?
First determine whether the line will carry power, control signals or data. Then clarify the operating voltage, load current, line length and installation environment. Choose the family that suits your application from the cable category.
Is the cable cross-section chosen by current alone?
No. Current carrying capacity, voltage drop and short-circuit withstand strength are checked together. Ambient temperature, cable grouping and installation method also change the result. The current carrying capacity calculation and the voltage drop calculation help with a preliminary assessment.
Are cables with the same cross-section interchangeable?
Not always. Insulation, shielding, flexibility and fire performance may differ. For power lines, see the difference between NYY and N2XH; for signal lines, see the difference between LIYY and LIYCY.
What should be checked before ordering?
Verify the manufacturer code, the number of cores, the core cross-section and the required length. Check the sales unit and minimum quantity on the product page. If there is a fire requirement, read the distinction between halogen-free and fire-resistant cables. Confirm the final selection against the project and the manufacturer's datasheet.
Technical sources
- Schneider Electric: cable cross-section selection method
- Prysmian: conductor cross-section calculation
Comparison and selection table
| Circuit & Application | Standard PVC Installation | Halogen-Free (LSZH Fire Safety) | Flexible / Shielded / Heavy-Duty Option |
|---|---|---|---|
| Indoor Fixed Wiring | NYA (H07V-U/R) in conduit, NYM surface/flush | H07Z1-U/R (LSZH single-core), NHXMH | H05VV-F (TTR) flexible appliance & extension cord |
| Main Power & Underground | NYY (0.6/1 kV PVC), NAYY (aluminum feeder) | N2XH (0.6/1 kV XLPE/LSZH), N2XH FE180 (E90) | H07RN-F heavy-duty rubber cable for cranes & sites |
| Machine Control | YSLY-JZ / YSLY-OZ numbered control cable | HSLH-JZ / LIHCH halogen-free control/signal | YSLYCY braided-shield control, PUR drag-chain cable |
| Low-Current & Data | LIYY signal, CAT6 U/UTP, J-Y(St)Y alarm cable | JH(St)H LSZH fire alarm, CAT6 LSZH | LIYCY / LIYCY-TP tinned-copper shielded signal cable |
Frequently asked questions
Is current-carrying capacity (ampacity) alone enough to size a power cable?
No. You must also verify maximum permissible voltage drop over the run length (typically 1.5% for lighting and 3% for power feeders) and short-circuit thermal withstand; on long cable runs, voltage drop often requires stepping up one or two conductor cross-sections.
Which cable type should be used for direct underground burial?
Underground trenches and ducts require 0.6/1 kV heavy-duty NYY (YVV) power cables (or steel-armored NYRY / NYFGY where mechanical impact risk is high); indoor building wires (H07V-U) or light PVC cords (H05VV-F) must not be buried directly in soil.
Why are fine-stranded (Class 5) conductors specified for machinery and control wiring?
Solid (Class 1) or coarse-stranded (Class 2) conductors fatigue and fracture under vibration or repeated flexing, whereas Class 5 fine-stranded copper cables (YSLY-JZ, LIYY, LIYCY, H07RN-F) withstand tight panel routing and machine movement.