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Mains connection cable and the cross-section: a crucial detail
Mains connection cable and cross-section: a crucial detail
The conductor cross-section influences 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.
MAG GmbH · 38268 Lengede (Lower Saxony) Orientation (10A, 3-pin): 0.75 / 1.0 / 1.5 mm² depending on length More cross-section = less loss
Standard orientation for 10A mains connection cables (3-pole)
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 mm² |
| 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 1.5 mm² is appropriate
- Continuous operation/long running times: less heating, more reserve.
- Longer cables or additional power strips: lower voltage drop.
- IT/industry/measuring 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/couplings. With C13, the application is typically designed for 10A – 1.5 mm² primarily provides reserve capacity for losses/heating within this limit.
Facts – brief and understandable
- 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 (20 °C) for classification:
| 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, thereby lowering voltage drop and heat generation, especially with long lengths and continuous loads.
Example (simplified): 10A with a cable length of 5 m
Round trip conductor approx. 10 m conductor length (5 m × 2). The example shows the order of magnitude:
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: 3 questions – clear recommendation
The recommendation remains honest: what is sufficient is also named as such. If 1.5 mm² makes sense, it is clearly highlighted.
MAG power cable with above-average cross-section (1.5 mm²)
When reserve capacity counts: 1.5 mm² reduces losses and heating – especially with longer cables or continuous loads. For standard applications, a smaller cross-section may be sufficient.
- More reserve for demanding setups
- Lower losses with longer cables
- Reduced heating under continuous load
