| Conductor Size (mm²) | Rating in open air (clipped) | Rating buried in insulation | Typical Circuit Breaker | | :--- | :--- | :--- | :--- | | 1.0 mm² | 12 Amps | 8 Amps | 6A or 10A (Lighting) | | 1.5 mm² | 16 Amps | 10 Amps | 10A or 16A | | 2.5 mm² | 24 Amps | 14 Amps | 16A or 20A (Outlets) | | 4.0 mm² | 32 Amps | 18 Amps | 20A or 25A | | 6.0 mm² | 41 Amps | 23 Amps | 32A (Cooker/Oven) | | 10 mm² | 57 Amps | 32 Amps | 40A or 45A | These are estimates . Local electrical codes (NEC in US, BS7671 in UK, AS/NZS 3000 in Australia) provide exact tables that must be followed. Voltage Drop: The Long-Distance Problem If your cable run is very long (e.g., from the main house to a garden shed 50 meters away), you encounter voltage drop . The resistance of the long wire reduces the voltage reaching the device. This can cause motors to burn out and lights to dim.
Whether you are wiring a new shed, installing a high-powered kitchen appliance, or simply choosing an extension lead, understanding electric cable sizes is crucial. Choosing the wrong size doesn't just mean your device won't work properly—it can lead to dangerous overheating, melted insulation, and electrical fires.
| Conductor Size (mm²) | Rating in open air (clipped) | Rating buried in insulation | Typical Circuit Breaker | | :--- | :--- | :--- | :--- | | 1.0 mm² | 12 Amps | 8 Amps | 6A or 10A (Lighting) | | 1.5 mm² | 16 Amps | 10 Amps | 10A or 16A | | 2.5 mm² | 24 Amps | 14 Amps | 16A or 20A (Outlets) | | 4.0 mm² | 32 Amps | 18 Amps | 20A or 25A | | 6.0 mm² | 41 Amps | 23 Amps | 32A (Cooker/Oven) | | 10 mm² | 57 Amps | 32 Amps | 40A or 45A | These are estimates . Local electrical codes (NEC in US, BS7671 in UK, AS/NZS 3000 in Australia) provide exact tables that must be followed. Voltage Drop: The Long-Distance Problem If your cable run is very long (e.g., from the main house to a garden shed 50 meters away), you encounter voltage drop . The resistance of the long wire reduces the voltage reaching the device. This can cause motors to burn out and lights to dim.
Whether you are wiring a new shed, installing a high-powered kitchen appliance, or simply choosing an extension lead, understanding electric cable sizes is crucial. Choosing the wrong size doesn't just mean your device won't work properly—it can lead to dangerous overheating, melted insulation, and electrical fires. electric cable sizes