NM Cable (Romex)
CSI Division 26, Electrical
Nonmetallic sheathed cable, commonly known by the brand name Romex, with multiple insulated conductors bundled together inside a single plastic jacket, as distinct from conduit, where individual conductors are pulled separately through a protective metal or plastic tube.
Why it matters
Which wiring method a job requires, NM cable or conduit, depends heavily on the building type and local code: NM cable is common and economical in residential framing, while commercial work and many jurisdictions require conduit instead, since conduit offers more physical protection and makes future wire changes easier.
On a real project
An electrician wiring a wood-framed house runs NM cable through drilled holes in the studs to reach each outlet and switch location, while a commercial electrician on a different job pulls individual conductors through metal conduit instead, since the commercial building's code requires it.
Who this matters most to
An Electrician chooses between NM cable and conduit based on the building type, local code, and the specific application, not out of simple preference.
Where this goes wrong
An electrician runs NM cable in an application where local code actually requires conduit, assuming the two methods are interchangeable. An inspector rejects the rough-in, and the cable has to be pulled out and replaced with properly conduited wiring before the job can pass inspection.