Conductor classes and strand construction: why fine stranded is not always fine stranded
Two cables with the same cross section can behave in completely different ways. The decisive factor is the construction of the conductor. It has consequences for flexibility, crimping and connection.
The conductor classes
The standard for conductors of cables and insulated leads divides copper conductors into classes according to their construction:
- Class 1 (solid): a single solid wire, rigid, for fixed installation
- Class 2 (stranded): a few thicker wires, still largely rigid
- Class 5 (fine stranded): many thin wires, flexible
- Class 6 (extra fine stranded): very many, very thin wires, highly flexible
The factors that decide the class include the maximum diameter of the individual wires and the conductor resistance. The cross section on its own therefore says nothing about flexibility.
What the construction means in practice
- Flexibility: the finer the wires, the better the cable copes with movement and tight radii
- Crimping: contacts are approved for particular conductor constructions; a different construction can change the crimp quality
- Terminals: in many terminals, fine stranded conductors need wire end ferrules
- Stripping: fine wires are more sensitive to nicks
Choosing the right construction
For cables that are installed permanently, a simple construction is often enough. Where cables move, vibrate or are routed in tight spaces, fine stranded conductors are the better choice. What matters is that cable, contact and tool match each other. We check this during sizing.
When stripping fine strands, a clean cut is what counts: the Schleuniger B340 in our production works with four rotating blades that cut into the insulation concentrically, without damaging the conductor.
