What is the ampacity of a No. 4/0 THHN copper conductor under regular conditions?

The ampacity of a No. 4/0 THHN copper conductor is primarily determined by the National Electrical Code (NEC) and is influenced by factors such as insulation type, temperature, and the number of conductors in a raceway. For No. 4/0 THHN copper conductors, the standard ampacity under regular conditions—which typically consider a temperature rating of 90°C and a single conductor in free air—is indeed 260 amps.

This value reflects the conductor's ability to safely carry current without exceeding its temperature rating, thereby preventing potential overheating and maintenance issues. When working with electrical systems and choosing conductors, adhering to these ampacity ratings is crucial for ensuring safety and compliance with electrical codes.