Master Electrician Practice Exam

What wiring method is permitted for service risers installed in wet locations that contain THWN insulated conductors?

1. PVC Conduit

2. Electrical Metallic Tubing (EMT)

3. Flexible Metal Conduit

4. Non-metallic Sheathed Cable

The correct answer is: Electrical Metallic Tubing (EMT)

The correct choice is Electrical Metallic Tubing (EMT) because this wiring method is suitable for service risers installed in wet locations when using THWN insulated conductors. EMT provides a level of mechanical protection and resistance to moisture, making it appropriate for such applications. EMT is often used in environments where water can accumulate, as it helps safeguard the conductors from physical damage as well as corrosion due to moisture. Additionally, the metallic surface of EMT can aid in grounding and is often compatible with various connectors and fittings used in electrical installations. Other choices such as PVC Conduit, Flexible Metal Conduit, and Non-metallic Sheathed Cable may have limitations in terms of their performance in wet environments or mechanical stability as service risers. While PVC Conduit also works in wet locations, it may not provide the same level of mechanical protection as EMT. Flexible Metal Conduit, although it can offer some protection, is not typically recommended for service risers due to limitations in rigidity and possible corrosion in prolonged wet conditions. Non-metallic Sheathed Cable is generally not permissible for vertical runs in service risers in wet locations due to its lack of adequate moisture protection and support for the voltage typically seen in service applications. Thus, EMA is the best