1. General Principles for High Current
When selecting a cable, the following points are particularly considered:
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Continuous current carrying capacity (Iᴀmp):
It is selected from the catalogue/standard according to the cable cross-section, ambient temperature and installation method. -
Short-circuit withstand capability:
The cable must withstand the heating that occurs during the time until the protection device trips (for example 1 s). -
Voltage drop:
On long lines, the cross-section is increased so that the voltage at the load does not drop excessively. -
Environmental conditions:
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Outdoor / sun / humidity / chemical exposure
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Is the cable in a tray, in a conduit, or underground?
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Fire safety:
In enclosed spaces, halogen-free, low-smoke cables are preferred. -
Copper or aluminium?
Copper is a better conductor but more expensive; for high currents, aluminium + larger cross-section or a busbar is often the economical solution.
2. Cable Types Used in Low-Voltage (0.6/1 kV) High-Current Lines
2.1. XLPE Insulated Power Cables
(E.g. N2XY, N2XH, YXV etc.)
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Where? Between main distribution panel and sub-panels, large motor supplies, generator outputs.
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Characteristics:
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XLPE (cross-linked polyethylene) insulation → high temperature resistance (typically 90°C)
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Can carry more current than PVC for the same cross-section.
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Can be with copper or aluminium conductors.
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Why is it preferred for high currents?
High current → high heating; since XLPE has high temperature resistance, it is safer.
2.2. PVC Insulated Power Cables
(E.g. NYY, NYM)
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Where? Main building feeders, panel internal wiring, medium level currents.
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Characteristics:
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Economical and widely available.
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Continuous operating temperature is typically around 70°C.
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In high-current applications:
As current increases, it reaches its limit more quickly than XLPE cable of the same cross-section. For applications requiring very high currents, XLPE or busbar is generally preferred.
2.3. Flexible Rubber Insulated Cables
(E.g. H07RN-F type)
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Where?
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Mobile connections between generator and panel
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Cranes, moving machinery, welding machines
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Characteristics:
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Rubber insulation → good resistance to mechanical impact, oil and outdoor conditions.
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Multi-core, highly flexible → used on frequently moving equipment.
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High-current aspect:
With a sufficiently large cross-section, currents of 200–300 A and above can be carried; however, since it is a flexible cable, it is more commonly used for mobile/portable power supplies than for long permanent lines.
3. For Very High Currents: Bar and Busbar Systems
When currents reach the order of 400 A, 630 A, 1000 A, 4000 A, in most facilities instead of cables:
3.1. Copper / Aluminium Bar (Busbar)
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Used inside panels and for short-distance main distribution.
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Advantages:
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Can carry very high currents in a compact structure.
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Compared to cable bundles, installation and cooling are more controlled.
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Can withstand large short-circuit currents.
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3.2. Busbar Trunking (Busway Systems)
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Where? Large industrial plants, shopping malls, high-rise buildings.
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From the main distribution panel to floor panels, the line is run using pre-fabricated, metal-enclosed busway channels.
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A practical, modular and fire-manageable solution for high currents.
4. High-Current Lines in Medium Voltage (MV)
If by “high-current line” you mean MV cables between 6–36 kV, typical cables are:
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XLPE insulated single-core MV power cables
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E.g. single-core, copper/aluminium conductor, screened cables (12/20 kV, 18/30 kV etc.).
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MV overhead line conductors
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E.g. AAC, AAAC, ACSR type conductors (aluminium and steel-reinforced).
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Here, “high current” refers to the load currents depending on transformer rating flowing through the MV bus/cable; cable selection is made taking into account short-circuit currents and thermal limits.
5. Other Special Cables (Often Seen Together with High Current)
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Halogen-free, low-smoke cables (HFFR / LSZH)
Used where fire safety is critical (malls, hospitals, metro). -
Solar (PV) cables (high current on the DC side)
E.g. H1Z2Z2-K; DC cables that are UV and outdoor resistant and can operate at high temperatures. -
High-temperature cables (silicone, glass-fibre)
Used in environments such as furnaces and foundries where there is both high current and high ambient temperature.
6. A Practical Approach: What to Use in Which Case?
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Panel–panel, panel–large motor/generator (0.4 kV)
→ Generally XLPE insulated power cable (N2XY, N2XH, YXV) or for very high currents a busbar -
Main riser feeders inside buildings
→ PVC (NYY) or XLPE (N2XY/N2XH), depending on current and fire requirements -
Mobile power (mobile generator, large welding machines, cranes)
→ Flexible rubber insulated H07RN-F types -
Main distribution of very high-power industrial facilities (e.g. 2000–4000 A)
→ Most of the time a busbar trunking system -
MV side (transformer inlet/outlet, MV ring feed)
→ XLPE insulated MV power cables or ACSR/AAAC overhead line conductors
7. Important Note
Cable/conductor selection, in accordance with the relevant national standards (e.g. TS/IEC 60364 etc.), must be based on:
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Rated line current
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Short-circuit current and duration
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Installation method, ambient temperature, grouping factors
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Voltage drop limits
and calculated by a licensed electrical engineer. The information here is of a general guidance nature.