“Evaluating Safety Risks of Nonmetallic-Sheathed Cable in Legacy Industrial Buildings”


Nonmetallic-sheathed cable, commonly known as Romex, has been widely used in residential and commercial buildings for decades. However, its use in industrial facilities poses some unique safety considerations that facility managers should carefully evaluate. In this article, I will provide an in-depth look at the risks of using nonmetallic cable in legacy industrial buildings and how to assess if replacement or remediation is warranted.

What is Nonmetallic-Sheathed Cable?

Nonmetallic-sheathed cable, also referred to as Romex, consists of two or more insulated conductors wrapped in a nonmetallic sheath. The most common type is NM-B cable which contains insulated hot and neutral conductors and an uninsulated ground wire. The nonmetallic sheathing is often made of PVC or other thermoplastic material.

Compared to metal-clad cables, nonmetallic cables are lighter weight, more flexible, and lower cost. They also do not require specialized tools to install. This makes them well suited for residential and commercial wiring projects.

Why Was Nonmetallic Cable Used in Industrial Facilities?

In the past, nonmetallic cable gained popularity in industrial facilities for the following reasons:

Risks of Using Nonmetallic Cable in Industrial Environments

While suitable for residential and commercial settings, Romex can pose safety hazards when used in the harsher industrial environment:

Physical Damage

Environmental Exposure

Overcurrent & Overload Conditions

Ground Faults

Options for Remediation

Recognizing the risks posed by legacy nonmetallic cabling, facility managers have several options to improve safety:

Full Replacement

Selective Replacement

Improved Protection

Enhanced Monitoring

Ongoing Risk Assessment


While nonmetallic-sheathed cable was used extensively in the past, its safety risks are now well recognized. Assessing the current condition of Romex cables and gradually replacing damaged or high-risk sections can help mitigate hazards in older industrial facilities. A combination of replacement, improved protection, monitoring, and assessment is the most strategic approach.