What type of insulation must single-conductor PV system cables have for outdoor use?

Single-conductor photovoltaic (PV) system cables used for outdoor applications are specifically required to have insulation types that provide adequate protections against environmental factors like moisture, temperature fluctuations, and UV exposure. The most appropriate insulation type for this scenario is USE-2 (Underground Service Equipment) and RHW-2 (Rubber High Heat and Water Resistant).

USE-2 insulation is designed for direct burial applications, making it suitable for installations where cables are exposed to moisture and temperature variations. Additionally, its ability to withstand ultraviolet light makes it a good choice for outdoor use. RHW-2, on the other hand, is also rated for heat and water resistance while providing good durability in outdoor settings.

This combination of insulation types ensures that the cables can operate safely and effectively in outdoor conditions typical within PV system installations, making Option A the correct choice. In contrast, the other options either include insulation types that are not specifically rated for outdoor use in the same way or do not comply with the requirements set forth in the National Electrical Code.