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What is 12/3 Wire Used For?

Most lighting and socket circuits in your home use Romex, labeled as “12-2” or “12-3”. The first digit denotes the gauge wire. The second digit represents the number of conductors. However, with these differences, most people do not know what 12/3 is used for.

In general, 12/3 wires are used to connect a wall switch box to an outlet and connect switched lines to the ceiling fan. In addition, you can also use 12 3 wires for supplying a long stretch of incandescent light; and utilize them for smoke alarm circuits.

Typically, you can choose 10, 12, or 14 gauge wire. Romex 12-2 will have a black (hot) and white (neutral) wire and an unsheathed copper ground wire. A 12-3 Romex has a black (hot), red (hot), white (neutral), and bare copper conductor; the red on a 12-3 is for three-way light switches. In this guide, we will go through what 12 3 wires are used for.

Uses Of 12/3 Wire

12/3 wire in zoom

There are many possible uses of a 12/3 cable. If you are wondering what is 12 3 wire used for, the following are its most common uses:

  • 12/3 connects a wall switch box toward a switched outlet while carrying both switched and unswitched power.
  • You can also use 12/3 to connect two switched lines to the ceiling fan, one for the fan and one for a light kit.
  • When supplying a lengthy stretch of incandescent lighting outside, 12/3 wire might be utilized to equalize the voltage drop.
  • In smoke alarm branch circuits where the units are attached, 12/3 wire is also utilized (which is required these days). Red is typically used as an interconnect wire.

However, if you do not know how to identify and utilize different types of wires, it is best to contact a professional from a known wire service.

What Is The Purpose Of the 12 Denotion for Electrical Wire?

cut 12/3 wires in yellow, orange, and black

14 – Wire is for Light fixtures and Receptacles or Common Residential Wiring.

12 – Wire types are for Common Domestic Wiring, which includes your light fixtures, home receptacles, and small appliances.

10 – Wire types are used for Large household appliances, your window central air conditioning units, and clothes dryers.

When Would a 12/3 Wire be Appropriate to Utilize?

central air conditioning with electrical box

In structures, 12/3 wire is used for branch circuits that require more amperage than the typical 20 amps. Most people are unfamiliar with this wire since it connects high-power equipment like water heaters and central air conditioning. It should work fine with your heater and air conditioning. Ensure you use the proper air conditioning or heater to avoid a short circuit.

The Distinction Between 12/2 and 12/3 Wire: What is it?

12/2 refers to AWG 12 wire with two conductors (AC hot and AC neutral), whereas 12/3 refers to AWG 12 wire with three conductors (two AC hot and AC neutral). In both cases, a smaller bare copper earth ground conductor is included. AWG 12/2 is used for circuits with a single 120V 20A maximum breaker.

When Is It Appropriate to Use 12/2 Wire?

12-2 is suitable for 15A and 20A circuits. In the United States, 12-2, a 20A breaker, and 15A receptacles can be used (as long as you have more than one receptacle on the circuit). It is adequate for 15 to 20 amps. #12 American Wire Gage (AWG) Copper wire is suitable for any circuit carrying no more than twenty amperes. (1)

NEC Regulations for Romex Conductors

Romex conductors are subject to the following NEC or the National Electrical Code regulations: (2)

  • They must be secured, protected, and clamped to equipment boxes, junction boxes, and fixtures.
  • Support devices that might harm the cables, including bent nails and overdriven staples, are not allowed.
  • You should secure NM and NMC cables at no more than 412 feet intervals and within 12 inches of connectors and panels to which they are connected. Cables that do not follow this regulation may droop and become damaged.
  • They are designed for permanent residential wiring and should not be used as a replacement for appliance wiring or extension cables.

Take a look at some of our related articles below.

(1) Copper – https://www.livescience.com/29377-copper.html
(2) NEC – https://www.techtarget.com/searchdatacenter/definition/

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About Sam Orlovsky

AvatarCertifications: B.E.E.
Education: University Of Denver - Electric Engineering
Lives In: Denver Colorado

Electrical engineering is my passion, and I’ve been in the industry for over 20 years. This gives me a unique ability to give you expert home improvement and DIY recommendations. I’m not only an electrician, but I also like machinery and anything to do with carpentry. One of my career paths started as a general handyman, so I also have a lot of experience with home improvement I love to share.

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