New York State Master Electrician Practice Exam

Which type of cable is specifically identified for use as underground service-entrance cable?

1. NM Cable

2. USE Cable

3. THHN Cable

4. SE Cable

The correct answer is: USE Cable

The identification of USE cable as the correct type specifically intended for underground service-entrance applications is based on its design and construction. USE, or Underground Service Entrance cable, is crafted to withstand the conditions present in underground installations. It is resistant to moisture and chemicals, which is essential for ensuring the integrity and longevity of electrical connections when buried underground. USE cable features a durable outer jacket that protects the conductors from environmental factors, making it suitable for direct burial in earth or in wet locations. This specific construction allows for secure and reliable delivery of electrical service to buildings without the need for additional protective conduits. In contrast, other cable types such as NM (non-metallic) cable and THHN (Thermoplastic High Heat-resistant Nylon-coated) cable are not designed for such underground applications. NM cable is typically used for interior wiring and lacks the necessary moisture resistance for underground use. THHN cable is commonly used for dry locations and typically requires additional protection when used underground due to its limited ratings against moisture and physical damage. SE cable, while used for service entrance applications, is primarily suited for above-ground service and does not have the same designation for direct burial applications as USE cable does.