What is the minimum size of secondary conductors for a transformer supplying power?

The minimum size of secondary conductors for a transformer supplying power depends on several factors, including the transformer's output voltage, the load capacity, and the specific requirements set forth by the National Electrical Code (NEC) for conductor sizing. In the context of transformers, secondary conductors must be sized adequately to safely handle the expected load without overheating or causing voltage drop.

When determining the minimum size, it’s important to consider the ampacity of the conductors at the transformer’s output. In general, larger conductors are required to ensure that they can handle the maximum expected current without exceeding the temperature ratings of the wire. 250 kcmil, as the maximum minimum size in this context, ensures that there is sufficient capacity to accommodate the load while providing a margin for safety and efficiency.

Using larger conductors minimizes resistance and voltage drop, which is crucial in maintaining system performance. Therefore, the choice of 250 kcmil aligns with best practices for electrical installations, particularly when connecting to equipment like transformers where power demands can fluctuate significantly. This size ensures compliance with NEC standards and best practices for safe and reliable operation.