IBEW Electrical Practice Test 2025 – Complete Exam Preparation

Non-metallic sheathed cables, often referred to as NM cable or "Romex," are commonly used in residential wiring due to their ease of installation and lightweight nature. However, their use is restricted in certain locations, primarily due to their vulnerability to moisture. In high moisture areas, such as basements, crawl spaces, or locations prone to leaks, NM cables may not provide adequate protection. Moisture can lead to degradation of the insulation over time, which increases the risk of electrical faults, shorts, or even fire hazards.

The materials used in non-metallic sheathed cables are not as resilient as those in metal cables when it comes to moisture exposure. Therefore, it is crucial to adhere to code requirements and best practices when choosing the appropriate wiring for such environments, hence the restrictions in those areas for safety reasons. This ensures the integrity of the electrical system and protects against potential risks associated with moisture and electrical conductivity.