According to Article 690, what should be rated when selecting conductors?

When selecting conductors in accordance with Article 690, it is essential to consider the maximum system voltage or higher. This is because conductors must be able to handle the electrical demands of the system they are part of without risk of insulation breakdown or failure. The NEC emphasizes that conductors should have appropriate voltage ratings that match or exceed the voltage levels they will experience in operation.

Considering the maximum system voltage ensures that the conductor's insulation will not be compromised during normal operation or under fault conditions, thus maintaining safety and performance within a photovoltaic system. By selecting conductors rated for the maximum system voltage, you help prevent potential hazards like electrical arcing, fire, or damage to connected equipment.

Other considerations like ampacity and protection against overloads are also important in conductor selection, but they revolve primarily around ensuring safety and operational efficiency rather than focusing solely on voltage ratings. Therefore, understanding and applying the correct voltage rating is critical to compliance with the NEC and effective system performance.