Conductor class 5 or 6 to IEC 60228 - which to pick?
IEC 60228 sorts conductors into four classes. This guide explains when fine-stranded class 5 is enough and when finest-stranded class 6 is required, what that means for flexibility and bending radius, and which ferrules go with them.
View connectivity productsWhat sets class 5 apart from class 6?
IEC 60228 (adopted in Europe as EN 60228) defines four conductor classes. Class 1 is a solid single wire, class 2 a stranded circular conductor, class 5 is fine-stranded and class 6 finest-stranded. Classes 5 and 6 are the flexible conductors - the difference lies purely in the number and thinness of the individual strands.
At the same nominal cross-section, class 6 has many more and much thinner strands than class 5. The standard caps the maximum diameter of a single strand for each class so the promised flexibility is guaranteed. The electrical resistance per cross-section is identical in both classes, because it depends on the copper area, not on the strand count.
When is class 6 required over class 5?
The choice comes down to mechanical load. Class 5 is fine for fixed installation and occasional movement, such as inside a control cabinet or as a connecting lead. Class 6 belongs anywhere the conductor is moved continuously, bent tightly or routed through drag chains.
- Constant motion: robot arms, drag chains, moving machine axes - the fine strands of class 6 prevent wire fatigue from repeated flexing.
- Tight bending radius: class 6 allows smaller radii without permanent deformation of the conductor.
- Handling and assembly: very flexible conductors are easier to route and terminate in tight enclosures.
- Fixed wiring, short leads, control cabinet: here class 5 is economical and perfectly adequate.
- Control and signal cables with frequent plugging: class 6 extends the service life of the core.
Which ferrules do flexible conductors need?
Fine-stranded conductors of classes 5 and 6 must never be terminated in screw or spring-cage terminals without a ferrule. The ferrule gathers all the strands, stops them splaying and creates a gas-tight, lasting contact. Without one the connection loosens as the strands settle over time.
The ferrule is sized by nominal cross-section in mm², not by conductor class. Because class 6 has more strands, the real bundle can be slightly bulkier - if in doubt, crimp firmly and check the seating. Insulated ferrules with a colour-coded collar to DIN 46228‑4 make the correct match easy.
Frequently asked questions
Do class 5 and 6 carry different current?
No. IEC 60228 sets the same maximum conductor resistance per cross-section for both classes. At the same mm² the current rating is identical - class 6 is only mechanically more flexible.
Can I just use class 5 instead of class 6?
For fixed installation, yes. For continuous movement, drag chains or tight bends, no: the thicker strands of class 5 fatigue faster under repeated flexing. In those cases class 6 is the right choice.
Does class 5 really need ferrules?
In screw and spring-cage terminals, yes. Fine-stranded conductors of both classes must be fitted with a ferrule so the joint stays gas-tight and does not loosen as the strands settle.
Do I size the ferrule by conductor class?
No, by nominal cross-section in mm². The colour code to DIN 46228‑4 helps you match it. With class 6, check the seating after crimping, as the strand bundle is fuller.
Looking for the right stranded wire and ferrules?
We supply flexible conductors of classes 5 and 6 to IEC 60228 plus colour-coded ferrules to DIN 46228-4 - crimp tool included.
Standard-compliant
Conductors tested to EN 60228.
Secure termination
Ferrules to DIN 46228-4 for a gas-tight seat.
Matching tools
Calibrated crimp tools for repeatable crimps.
Expert advice
Our specialists help with class and cross-section.