Electrical Supplies…
Electrical Code…
A factory assembly of two or more insulated conductors enclosed within an overall nonmetallic jacket.
Type NM: Insulated conductors enclosed within an overall nonmetallic jacket.
This overall covering shall be flame retardant and moisture resistant.
Type NMC: Insulated conductors enclosed within an overall, corrosion resistant, nonmetallic jacket.
This overall covering shall be flame retardant, moisture resistant, fungus resistant, and corrosion resistant.
Type NMS: Insulated power or control conductors with signaling, data, and communications conductors within an overall nonmetallic jacket.
This overall covering shall be flame retardant and moisture resistant. The sheath shall also be applied so as to separate the power conductors from the communication conductors.
(National Electrical Code® 334.2, 334.116)
NT Commentary…
Nonmetallic Sheathed Cable, Romex:
This is Romex. You know, the stuff that replaced knob and tube wiring and that everybody and their brother is stringing and strangling their houses with straight out of the big box stores? So much romex has been unnecessarily used now that if you were to straighten all of it out, it would stretch around the earth 553 times. Well not really. I just made that up. But seriously, you have probably seen jobs where “inexperienced” and handy guys use about twice as much of this stuff as they have to because YouTube told em so. And have you ever wondered how you can lose a job to someone that uses three times as much copper? Funny, then you get a call in a couple months because the switches in the foyer don’t work because the guy didn’t know the difference between a 2-pole switch and a 4-way switch.
As always check your NEC (Article 334) and supplier for more info.
(NT)