SE service-entrance cables interior use requires conductors of the thermoset or thermoplastic type.

• A. thermoset
• B. thermoplastic
• C. a or b
• D. metal

Answer: (C)

Interior service-entrance conductors must be insulated with a material that provides reliable electrical insulation in typical indoor conditions. Thermoset and thermoplastic describe two different families of insulation polymers, and both are suitable for this use. Thermoset insulation cures into a rigid, heat-stable layer that won’t melt, while thermoplastic insulation stays flexible but can soften with heat. Either type around the conductor meets the requirement, which is why the correct choice is the option that includes both thermoset or thermoplastic. Metal, by contrast, would not provide insulation at all.