New York State Master Electrician Practice Exam

Which type of cables are permitted to enter the top of a surface-mounted enclosure?

1. Any flexible cables

2. Metallic sheath cables only

3. Nonmetallic sheath cables

4. Only underground rated cables

The correct answer is: Nonmetallic sheath cables

Nonmetallic sheath cables are specifically permitted to enter the top of a surface-mounted enclosure due to their construction and compliance with safety standards. These cables, often referred to as NM cables, are designed for dry indoor applications and are considered safe for use in various electrical installations. Their flexibility and the way they are constructed allow them to fit securely and safely into the enclosures without risking damage or exposing wires. In contrast, other cable types may not be suitable for top entry into surface-mounted enclosures. Flexible cables may not provide the necessary protection needed when exiting an enclosure. Metallic sheath cables, while durable, often have specific entry requirements due to their grounding and bonding considerations; they might require different entry points to avoid compromising their protective features. Underground-rated cables are typically designed for direct burial and may not be appropriate or compliant with surface-mounted installations. Each of these alternatives typically has specific guidelines for installation that differ from those applicable to nonmetallic sheath cables.