Copper Cable Sizing =link= Instant

| AWG/kcmil | Ampacity (75°C) | Typical Use | Max distance for 15A @ 120V (<3% drop) | | :--- | :--- | :--- | :--- | | 14 | 20A | Lighting, general outlets | 30 ft | | 12 | 25A | Kitchen outlets, 20A circuits | 40 ft | | 10 | 35A | Water heaters, AC units | 65 ft | | 8 | 50A | Small subpanels, ranges | 80 ft | | 6 | 65A | EV chargers, large ovens | 100 ft | | 4 | 85A | Subpanels, feeders | 130 ft | | 2 | 115A | Main feeders, heat pumps | N/A (requires calc) |

Real-world example: A 15A pump, 200 feet from the panel on 120V. Using 14 AWG (common for 15A) gives a 7.2% voltage drop. That pump will fail. You must jump to 10 AWG to drop to 2.8%. Myth 1: "Copper is copper." False. Pure copper (Cu-ETP) is standard. CCA (Copper-Clad Aluminum) is not copper; it requires a 2-step larger size. And "tinned copper" is for marine/corrosive environments but has identical ampacity. copper cable sizing

The best electricians don't just read ampacity tables; they understand why the table says what it does. They account for the heat, the distance, and the neighbors in the conduit. | AWG/kcmil | Ampacity (75°C) | Typical Use

Next time you strip a piece of 10 AWG, remember: That 2.6mm diameter of copper is a precisely calculated lifeline. Treat its size with respect. You must jump to 10 AWG to drop to 2