Resistance versus conductor area for copper power cables, for 0 to 35 mm2. The American Boat and Yacht Council E-11 data (30°C) data I found at Blue Sea. The Tycab (20°C) data are from the manufacturer. The IEC 60827 data (20°C) I found at myElectrical Engineering LINK. The NEC data (20°C, solid core) are from Wikipedia. The Olex data are from the manufacturer.