What type of wire is appropriate for both indoor and outdoor use?

USE (Underground Service Entrance) cable is designed specifically for outdoor use, particularly for underground installations where moisture and environmental factors are significant concerns. This type of wire is constructed with durable insulation and materials that can withstand exposure to the elements, making it suitable for direct burial applications. It ensures safety and reliability in outdoor settings, which is crucial for electrical services that will be exposed to water or other harsh conditions.

While other types of wire may be rated for specific indoor environments, they may not have the same durability or moisture resistance as USE cable, which is why it is chosen for both underground and outdoor contexts. It's important to consider that choices like NM cable are meant for indoor usage and would not be safe or appropriate for outdoor installations. Solid wire is often used for specific applications but doesn’t inherently offer the protections needed for outdoor exposure, and THHN/THWN wire, while versatile, is typically used in conduit rather than direct burial unless specified for use in wet locations.