12/2 vs. 12/3 Romex Wire [What Is The Difference Between Them]

Understanding how the wires are categorized is vital in knowing how best to use them also. That is why we look into how 12/2 and 12/3 differ and where best to use both wires.

Starting with the 12/2, we find that it features 12 gauge wires. These are vital cables that can carry up to 20A of current.

That is not all; the second number after ” / ” means the cable has two conductors. The black one is for hot or live wire, and the white one is for the neutral wire.

The 12/3 has similar construction, only that there are three conductors this time around rather than two.

They include black for live, white for neutral, and red for life also. It is easy to differentiate the two because of the additional conductor.

The additional red wire makes the 12/2 a good pick for three-way switches.

In both cases, there will be a bare ground wire too. Any circuit connection should always have ground.

Looking at how much current the 12/3 can carry, we find it is the same as that of 12/2. It is only that you can configure it differently.

Can You Use 12/2 and 12/3 for Lighting Circuits?

The 12 gauge wire is generally used for lighting and outlets. This is thanks to its capacity.

In case you just want to do the wiring for lights alone, then a 14-gauge wire can do the job. However, we use the 12-gauge wires because they can handle more power if you have a bigger appliance connected to the outlet.

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Here is a video with more details on how 12/2 and 14/2 differ

YouTube video

Another reason for having the 14-gauge wire for outlets is that you might have many outlets on the same line. This could potentially lead to a voltage drop. So, having a 12-gauge line means it can sustain the continuous draw of a huge current.

You are still advised to use the correct breaker for the job. Each time you wire a 12-gauge wire, ensure you use a 20-amp breaker. Even if the appliances never exceed 15 amps, always match the correct breaker rating.

The 12/2 cable can also be used for cases where you have to wire a heater. However, this would be a small heater compared to what people use most of the time.

If you want to wire the huge heaters, consider the 10-3 cables. They can handle 30A.

You can always learn more about the Romex wires and their uses from the guide below

YouTube video


Where are the 12/3 cables used when wiring a house?

This cable can be used mostly for wiring appliances that draw a lot of currents such as the central air conditioning and water heaters. So long as the appliance does not need more than 20A to run, this would be the right cable.

What is the main difference between 12/2 and 12/3?

It should be the number of conductors. The 12/3 cable has 3 conductors, while the 12/2 has only two conductors.

Can you use the 12/2 cables for powering water heaters?

It depends on the size of the water heater. Sometimes you may have to opt for a 10/2 cable if the heater is rated over 3700 watts.

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