What Is NM Cable?
NM cable is a factory-assembled wiring cable with insulated conductors enclosed in a nonmetallic outer jacket. The cable carries electrical current through branch circuits inside dry, protected building spaces. Its jacket keeps the conductors together and helps identify the cable as a finished wiring assembly for residential electrical work.
Quick Facts About NM cable
Category
Nonmetallic-sheathed wiring cable
Used for
Residential branch-circuit wiring
Common confusion
Not a type of conduit
Also called
Nonmetallic cable, Romex
Often discussed with
Whole-home rewiring
Key Takeaways About NM cable
- The nonmetallic jacket surrounds multiple insulated conductors.
- NM cable suits protected, dry wiring spaces.
- NM cable is not the same as conduit.
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How NM cable Works
NM cable carries electrical power through insulated conductors contained within one outer jacket. The conductors connect a branch circuit between the electrical panel, switches, receptacles, and lighting outlets. The cable jacket keeps the conductors organized during installation and helps protect them from ordinary contact within suitable building spaces.
Related glossary terms: Conduit, Electrical grounding, Junction box.
Installers select cable based on the circuit design, conductor size, grounding arrangement, and the building conditions around the route. NM cable is commonly secured along framing and brought into electrical boxes, where the jacket ends and individual conductors connect to devices or splices. Conduit serves a different purpose because it is a separate protective raceway that receives wires inside it.
From the Center Electric Service team
When we inspect NM cable during whole-home rewiring, we trace each cable from the panel to its connected devices. We check the jacket, conductor condition, box entries, grounding path, and routing conditions. Our team also matches the cable installation to the circuit design before making connections.
NM cable in Practice: A Real-World Example
During a whole-home rewiring project, NM cable may run from the electrical panel through accessible wall framing to a bedroom receptacle and lighting switch. The cable enters electrical boxes, where the conductors are connected to the devices and the circuit grounding path.
Related Services
Related Terms
Conduit
Conduit is a protective pathway that houses electrical wires and cables. It may be made from…
Electrical grounding
Electrical grounding is the intentional connection of electrical equipment and circuits to the earth or a…
Junction box
Junction box is an enclosed electrical container that protects and organizes wire connections where circuits meet…
Wire gauge
Wire gauge is a standardized system for describing a conductor's diameter and current-carrying capacity. Gauge numbers…
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Have Questions About NM cable?
Contact Center Electric Service for practical guidance on NM cable and related electrical services work in Riverside.