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NM Cable (Romex®)

14 AWG NM Rated for 15 Amps

12 AWG NM Rated for 20 Amps

10 AWG NM Rated for 30 Amps

NM is a type of cable that contains insulated conductors enclosed within an overall nonmetallic jacket. It is commonly known as “Romex®”, which is the brand that is most widely used. NM cable contains two or more insulated wires and a bare ground wire. NM is normally used in one- and two-family dwellings, and certain multifamily dwellings. NM-B is what you will see when shopping for NM cable, which is rated for 90 degrees C (194 degrees F).

There are many different ways to wire a dwelling during initial construction using NM cable.

The most common type of NM used are 2-wire and 3-wire.

A 2-wire NM contains one black wire (usually line) and one white wire (usually neutral) and a bare ground wire. When used in switch wiring, the white wire is sometimes used as a line wire.

A 3-wire NM contains a black, red, white, and a bare ground wire. The black and red wires can be used for line voltage A and B phases, or as travelers in 3- or 4-way switch wiring.

12-2

Wire AWG

Number of current carrying conductors

A 12-2 NM cable (2-wire) contains 2 insulated 12 AWG current carrying conductors (black and white) and a bare ground wire.

A 14-3 NM cable (3-wire) contains 3 insulated 14 AWG current carrying conductors (black, red, white) and a bare ground wire. The 2 line wires are different phases (A and B) and share the neutral wire for return current.

10 AWG NM rated for 30 amps 12 AWG NM rated for 20 amps 14 AWG NM rated for 15 amps

NM Cable Circuit Ratings

Basic Electricity

Electrical Voltages

Electrical Ground

Low Voltage

Electrical Definitions

Ohm’s Law

Electrical Circuits

Multi-Wire Branch Circuits

Circuit Current Ratings

NM Cable (Romex®)

Wire Connectors