Journeyman Electrician Practice Exam

Where is nonmetallic sheathed cable permitted to be used?

1. In single-family homes only

2. In commercial buildings

3. In multi-family dwellings of Type III, IV, and V construction

4. In all electrical installations

The correct answer is: In multi-family dwellings of Type III, IV, and V construction

Nonmetallic sheathed cable, commonly known as NM cable or Romex, is specifically designed for use in residential and certain types of multifamily structures. It is permitted in multi-family dwellings of Type III, IV, and V construction because these building types adhere to specific safety standards and building codes that accommodate nonmetallic cable systems. In Type III construction, for example, the structural framing consists of noncombustible materials like steel or masonry with interior elements made of wood or similar combustible materials. This allows for the use of NM cable while ensuring fire safety and compliance with electrical codes. Types IV and V, often seen in wood frame construction, further support the use of NM cable due to their similar fire-resistant properties. Using nonmetallic sheathed cable is advantageous because it is lightweight, easy to install, and offers excellent insulation properties. However, it does not meet the requirements for certain high-risk environments, such as commercial buildings or in areas with specific fire codes, where more robust wiring systems might be mandated. Hence, its use in multi-family dwellings of Types III, IV, and V construction strikes a balance between practicality and compliance with safety standards in applicable residential contexts.