Conductor classes

What are the different types of conductor classes and how are they distinguished?

What are conductor classes?
What conductor classes are there and how are they differentiated?
Conductor class 1
Conductor class 2
Conductor class 5
Conductor class 6
Overview of the conductor classes
Areas of application of the various concutor classes

What are conductor classes?

How mobile electrical conductors need to be depends on their area of application and their tasks. Some may be relatively rigid, others require significantly more flexibility. How mobile wires are depends on the structure of the conductors and can be determined on the basis of the conductor class to which they are assigned. Conductor classes provide information, among other things, about how flexible (bendable) conductors and thus the respective wires are. They thus help to reduce the susceptibility of electrical systems to faults by selecting conductors of the appropriate class. The following guide introduces the conductor classes and reveals some information about how the respective conductors can be used.

What conductor classes are there and how are they distinguished?

The conductor classes are defined in the international standard IEC 60228. In Germany, the specifications are implemented in the standards DIN EN 60228 and VDE 0295. A fee is charged for obtaining these standards; however, there are free summaries and tables of contents of DIN EN 60228 available online as PDFs. The standards define the four conductor classes 1, 2, 5 and 6. Classes 3 and 4 are not currently assigned. A class 1 conductor is a single-wire variant. It is also referred to as a solid conductor. Class 2 is a multi-wired conductor, while classes 5 and 6 are fine or ultra-fine wired conductors. The VDE 0295 standard specifies values such as the maximum diameter and maximum resistance for the individual wires.

Conductor class 1

The single-wire conductors of conductor class 1 are suitable for fixed installations, for example for parts of the house wiring. They are not particularly flexible. As a rule of thumb for maximum flexibility, the cable should not be bent more than about four times its diameter. If low flexibility is not a problem, installation is often easy. Furthermore, cables with class 1 conductors are usually less expensive than cables with multiple wires. Wires can be either round or sector-shaped. The sector-shaped arrangement of the conductors allows for larger wire cross-sections than with a round conductor in the same cable. In addition, there are fewer cavities to be filled.

Conductor Class 2

The conductors of VDE 0295 class 2 are referred to as multi-wire conductors. The individual conductor here consists of seven wires (individual conductors), for example. They are also only suitable for fixed installations, as their flexibility is not particularly high either. Compared to solid conductors, however, they are somewhat more flexible. They are often used when cables with larger cross-sections are required for fixed installations. They are unsuitable for very flexible cables, which are used, for example, in continuously moving objects such as robotic arms in industrial production. There are also round and sector-shaped variants for conductors of conductor class 2. Sometimes, a distinction is also made between uncompacted and compacted class 2 conductors. The latter can have a smaller cable diameter for the same number of wires, which is advantageous for some installations.

Conductor class 5

Fine-wired conductors correspond to VDE 0295 class 5. Like the extra-fine wire variant, they are also called flexible conductors. However, this does not mean that there are no cables with class 5 conductors for fixed installation. In conductor class 5, several strands are partly connected to each other like a rope. Stranded conductors are individual conductors that consist of several wires, so that the number of wires in the wire can be significantly larger than in multi-wired conductors. While class 1 and 2 conductors are also available with aluminium conductors, the fine and finest-wired variants are made of copper. They are suitable, for example, for powering small household appliances, but also for industrial applications with increased cable flexibility requirements.

Class 6 conductors

Class 6 conductors are also referred to as fine-stranded. Compared to class 5, the number of strands and wires arranged around each other is even larger, which can further increase the flexibility and pliability of the wire. But be careful: for some applications, a strand can also be too fine. In some cases, frequent bending can cause wire loops to form, which can become potential breaking points. If in doubt, it's best to seek advice. Class 6 conductors are suitable for applications such as automation, machine and tool construction or transport systems.

Overview table of conductor classes

The specifications for the strand structure according to VDE 0295 include, among other things, information on the possible conductor cross-sections. The number of wires is non-binding from column 3 onwards. This means that other variants (number of wires/single wire diameter) are possible.

Cross-section in mm²	Stranded conductors	Multistrand conductors	Fine-stranded conductors	Extra-fine wire strands
Class 1	Class 2		Class 5	Class 6
1	1	2	3	4	5	6	7
0,04							20 x 0,05
0,05						14 x 0,07	26 x 0,05
0,08					10 x 0,10	21 x 0,07	40 x 0,05
0,09					12 x 0,10	24 x 0,07	51 x 0,05
0,14			18 x 0,10	18 x 0,10	18 x 0,10	36 x 0,07	72 x 0,05
0,25			14 x 0,15	32 x 0,10	32 x 0,10	65 x 0,07	128 x 0,05
0,34		7 x 0,25	19 x 0,15	42 x 0,10	42 x 0,10	88 x 0,07	174 x 0,05
0,38		7 x 0,27	12 x 0,20	21 x 0,15	48 x 0,10	100 x 0,07	194 x 0,05
0,5	7 x 0,30	7 x 0,30	16 x 0,20	28 x 0,15	64 x 0,10	131 x 0,07	256 x 0,05
0,75	7 x 0,37	7 x 0,37	24 x 0,20	42 x 0,15	96 x 0,10	195 x 0,07	384 x 0,05
1	7 x 0,43	7 x 0,43	32 x 0,20	56 x 0,15	128 x 0,10	260 x 0,07	512 x 0,05
1,5	7 x 0,52	7 x 0,52	30 x 0,25	84 x 0,15	192 x 0,10	392 x 0,07	768 x 0,05
2,5	7 x 0,67	19 x 0,41	50 x 0,25	140 x 0,15	320 x 0,10	651 x 0,07	1280 x 0,05
4	7 x 0,85	19 x 0,52	56 x 0,30	224 x 0,15	512 x 0,10	1040 x 0,07
6	7 x 1,05	19 x 0,64	84 x 0,30	192 x 0,20	768 x 0,10	1560 x 0,07
10	7 x 1,35	49 x 0,51	80 x 0,40	320 x 0,20	1280 x 0,10	2600 x 0,07
16	7 x 1,70	49 x 0,65	128 x 0,40	512 x 0,20	2048 x 0,10	4116 x 0,07
25	7 x 2,13	49 x 0,62	200 x 0,40	800 x 0,20	3200 x 0,10	6370 x 0,07
35	7 x 2,52	133 x 0,58	280 x 0,40	1120 x 0,20	4410 x 0,10	9100 x 0,07
50	19 x 1,83	133 x 0,69	400 x 0,40	705 x 0,30
70	19 x 2,17	189 x 0,69	356 x 0,50	990 x 0,30
95	19 x 2,52	259 x 0,69	485 x 0,50	1340 x 0,30
120	37 x 2,03	336 x 0,67	614 x 0,50	1690 x 0,30
150	37 x 2,27	392 x 0,69	765 x 0,50	2123 x 0,30
185	37 x 2,52	494 x 0,69	944 x 0,50	1470 x 0,40

Important: There are other rules for strand structure besides DIN EN 60228 and VDE 2095. In the USA, the AWG often provides important information for strand structure. The abbreviation AWG stands for ‘American Wire Gauge’, which is used to code wire diameters. The system works with AWG numbers. For example, AWG number 18 represents a conductor cross-section of 1.038 mm². In the metric system, this corresponds approximately to a cross-section of 1 mm².

Fields of application for the different conductor classes

To emphasise it again: Standards such as DIN EN 60228, sometimes referred to as DIN 60228, do not specify any fields of application. In principle, however, cables of all four conductor types can be used in high-frequency and low-frequency networks, with solid cables generally performing better in the high-frequency range. The following applies: Selecting the right conductor type ensures that installation is as simple as possible and helps to minimise the vulnerability of the cable system. It also helps to ensure compliance with important guidelines such as VdS 2025 ‘Electrical Cable Systems’.

Differences between fine, superfine and multi-wired conductors

The fundamental difference has already been mentioned: multi-wired conductors contain a few wires, super-fine wired variants contain a few more and super-super-fine wired versions contain quite a few. The resulting main distinguishing feature is the flexibility of the wires. A solid conductor consists of a single wire, a stranded wire of many wires. The different conductors can be recognised, among other things, by markings that are based on DIN VDE 0292. Here, letters stand for conductors of different properties, which can also be found in the conductor classes:

U: single-core (round)
R: multi-core (round)
D: fine-wire (for welding leads)
F: fine-wire (for flexible wires)
K: fine-wire (for fixed installation)
E: extra-fine wire (for welding leads)
H: extra-fine wire

Together with other markings, they provide information about cables. In the case of an H07V-K cable, the initial H stands for harmonised cable (not for finest-wired!). The 07 symbolises a possible rated voltage of 450 V (between the outer conductor and protective earth) and 750 V (between the outer conductors). The V is an abbreviation for a PVC sheath, the K stands for ‘finest wire’. Type abbreviations according to DIN VDE 0250 are also possible. Here, among other things, e stands for single-wire, F for fine-wire, L or Li for strand and Y for PVC. An example of a chosen designation such as LIFY thus refers to fine-wire strands with a PVC sheath.

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