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Mains connection cable and the cross-section: a crucial detail
Power cable cross-section: When 0.75 mm², 1.0 mm² or 1.5 mm² is the better choice
The conductor cross-section affects resistance, voltage drop and heating. In standard applications, a smaller cross-section may be sufficient. If the load, runtime or cable length are more demanding, 1.5 mm² is often the more robust choice.
B2B focus: Selection guide for purchasing, IT and industry Guidance for 10A, 3-pin: 0.75 / 1.0 / 1.5 mm² by length More cross-section = less loss
Quickly to the most important points
What cross-section size is common for 10A mains connection cables?
In practice, the cross-section is often increased as the cable length increases. This keeps the voltage drop lower and the cable heats up less under load.
| up to 2.0 m |
0.75 mm² |
| Over 2.0 m to under 5.0 m |
1.0 mm |
| from 5.0 m |
1.5 mm |
Note: Permissibility and rated current depend on the specific cable type, its approval and the marking on the product. These values serve as a guide – the specifications of the specific item are always decisive.
When is 1.5 mm² appropriate for power cables?
- Continuous operation and long running times: less heating, more reserve.
- Longer cables or additional power strips: lower voltage drop.
- IT, industry, measurement environment: more stable supply in demanding setups.
- Unclear conditions: 1.5 mm² is often the less stressful choice.
Important: a larger cross-section does not automatically increase the permissible current of plugs or couplings. With C13, the application is typically designed for 10A – 1.5 mm² primarily provides reserve capacity for losses and heating within this limit.
Facts about power cable cross-section explained briefly
- Resistance: small cross-section = higher resistance per metre.
- Voltage drop: under load, more voltage drops across the cable (U = I · R).
- Heating: power loss becomes heat (P = I² · R).
Guideline values for conductor resistance at 20 °C
| 0.75 mm² |
≈ 24.5 Ω/km |
| 1.0 mm² |
≈ 18.1 Ω/km |
| 1.5 mm² |
≈ 12.1 Ω/km |
Interpretation: 1.5 mm² reduces resistance. This reduces voltage drop and heat generation – especially with longer cables and continuous loads.
Example: 10A with a cable length of 5 m
The outward and return conductors together result in a conductor length of approx. 10 m. The example shows the order of magnitude and illustrates the difference between the cross-sections.
0.75 mm²
ΔU ≈ 2.45 V · Loss ≈ 24.5 W
1.0 mm²
ΔU ≈ 1.81 V · Loss ≈ 18.1 W
1.5 mm
ΔU ≈ 1.21 V · Loss ≈ 12.1 W
Selection guide: Which power cable cross-section is suitable?
The recommendation remains deliberately practical: what is sufficient is also stated as such. If 1.5 mm² is appropriate, this is clearly highlighted.
MAG power cable with 1.5 mm² for more reserve
When reserve capacity is important, 1.5 mm² is often the more robust choice: lower resistance, fewer losses and reduced heating – especially with longer cables or continuous loads. For standard applications, a smaller cross-section may be sufficient.
Typical advantages in B2B use
- More reserve for demanding setups
- Lower losses with longer cables
- Reduced heating under continuous load
FAQ on power cable cross-section
When is 0.75 mm² sufficient for a power cable?
For short cables and standard applications, 0.75 mm² may be sufficient. The specifications of the specific cable, its approval and the intended application are always decisive.
When is 1.5 mm² the better choice?
1.5 mm² is often useful for longer cables, continuous operation, demanding IT or industrial environments, and wherever more reserve is desired in case of voltage drops and heating.
Does 1.5 mm² automatically increase the permissible current?
No. The larger cross-section primarily reduces losses and heating. The permissible current continues to depend on the plug, coupling, cable type and approval.
Why is the cross-section more important for longer cables?
The resistance of the cable increases with length. A larger cross-section helps to reduce voltage drops and heat generation.
