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How To Tell If Wire Is 12 Or 14 Gauge? (+When To Use)

Knowing the gauge size and using them correctly is essential. For a general understanding, the thinner the wire, the lower the gauge number. When you compare a 12 and 14 wire gauge, the former is superior to the latter.

The primary difference between a 12 or 14-gauge wire is the thickness. A 12 gauge wire is 2.055 mm thick, and a 14 gauge wire is around 1.63 mm thick. Also, check the breaker of the circuit. A 20Amp circuit requires a 12 gauge or larger wire, whereas a 15 Amp may work with a 14 gauge wire.

Sometimes, the wires are often labeled as 12 or 14 gauge. But you need to know the right one. So, this article will clarify the primary differences between the two wire gauges to help you know the right one and use them in the right place.

Wire types

How do I tell if the wire is a 12 or 14-gauge wire?

If you are new to wiring, it isn’t easy to understand the right gauge size of the wires. 

Since the sizes 12 and 14 are quite close, people may assume that there is not much difference between the two.

As a result, they use the wrong wire for the wrong purpose. 

So, you should know the difference between the two wire gauges to determine the right size.

Below are some points which will help you know if the wire is a 12 gauge or a 14 gauge and distinguish between the two.

Wire thickness

The first and foremost step to understanding whether a wire is 12 or 14 gauge you need to determine the thickness of the wire. 

The thickness of the 12-wire gauges is 2.05-2.75 mm, whereas the thickness of the 14-wire gauges is 1.63-1.99 mm.

So, it is clear that the 12-wire gauges are quite thicker than the 14-wire gauges. 

There is a huge difference between the two.

So, do not ever consider both wires to be similar. 

The thickness of the 12-wire gauge is 26% more than the 14-wire gauge. 

It also contains a 56% larger cross-sectional area than the 12-wire gauge.

In a wire gauge measurement, the gauge number will decrease when the size increases. 

So, the bigger the size, the better the wire.

Do not get confused with the numbers.

Wire strength

Since the size and diameter of the 12-wire gauge is much higher than the 14-wire gauge, the former has more strength than the latter. 

The 12-wire gauge has more conductivity and durability than the 14-wire gauge. 

Since the 14-wire gauge is thinner, it will have less conductivity and durability. 

Generally, the strength of the wire is somewhat related to the thickness.

Since the 12-wire gauge thickness is more, the strength is higher. 

Since the 12-wire gauge is stronger, it will prevent electricity loss, overheating, and damage to the electrical circuits.

Wire weight

Thickness is related to every other point. 

The 12-wire gauge is thicker than the 14-wire gauge.

So, the 12-wire gauge will bear more weight than the 14-wire gauge. 

Due to the higher thickness, the 12-wire gauge will carry more mass than the 14-wire gauge.

The higher the mass, the more the weight. 

You can tell which wire gauge is 12 and 14 by lifting and weighing them. 

Besides, you should know that the higher the gauge number, the lighter the wire will be. 

Since the 14-wire gauges are a higher number than 12, they will be lighter than the 12-wire gauges. 

If you ever measure the two wires, you will notice that the 12-wire gauge is 40% heavier than the 14-wire gauge.

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Which wire gauge is cheaper?

The cost of the wire gauges is another way of differentiating the two wires. 

The bigger the wire, the higher the price. 

The 12-wire gauges are bigger, thicker, heavier, and much better than the 14-wire gauges. 

So, the 12-wire gauges are more expensive than the 14-wire gauges. 

The 12-wire gauges also carry huge current loads of 20 amperes. So, that is why they are costly. 

Though the 12-wire gauges are a high-quality wire and the best option for a 20 amp circuit, you can opt for something cheaper if you cannot afford them.

However, there are risks to using the high-numbered gauges.

For example, a lamp will blow up using a 14-wire gauge.

You can change the wire material according to your affordability.

Copper wires are quite expensive compared to aluminum and copper-clad aluminum wires. 

You can use 14 wire gauges for your house wiring.

But it is always better to go for the best one, which is 12 wire gauge.

Which wire should I use for the lights?

The 12-wire gauges are the best choice if you have a circuit with lights. 

Due to the weight and thickness, the 12-wire gauges are not as flexible as the 14-wire gauges.

But a 12-wire gauge on a 15 or 20-amp circuit is safer than the 14-wire gauge.

If you want to use 14 wire gauges, it can only carry a limited load of 15 amps.

A 12-wire gauge is better for lights since it has less resistance due to its thickness and large size. 

Besides, 12-wire gauges can carry more current loads than 14-wire gauges without overheating.

So, if you use 12 wire gauges for lights, there will be fewer chances of flickering.

Which one should I use?

Both wires have their purposes.

Just because a 12-wire gauge is stronger and handles more current, it doesn’t mean that the14 wire gauges are worthless.

Both have advantages, but it is always better to use 12-wire gauges since they have more benefits than 14-wire gauges. 

The type of wire gauge depends on which device you want to use and for what purpose. 

If you have a circuit of 15 amps or within it, then you can go for the 14 wire gauges.

But, it is better to use 12 wire gauges if you have 20 amps.

A 14-wire gauge is thinner and, thus, cannot carry huge current loads.

So, using them for heavy appliances or lights with a current load of more than 15 amps. 

The appliances and lights may get overheated and catch fire if the current load exceeds 15 amps.

What happens if I use 14 wire gauge in a 20 amp circuit?

GFCI outlet burn

Using a 14-wire gauge in a 20 amp circuit is not recommended.

If you have 20 amp circuits, use the 12 wire gauges. 

If you forcefully use 14 wire gauges in a 20 amp circuit, the outlets will not perform well.

They may also set electrical fires due to overloading. 

The current will overflow, melt the wire and circuit, and cause a fire hazard. 

A 14-wire gauge is designed for a 15 amp circuit only.

Outlets for the wire gauges

14 wire gauge

In general, you can use 14 wire gauges for a 15 amp circuit and within it. 

Amperages of more than 15 can overload the wire. 

According to the NEC (National Electric Code), a 15 amp circuit can draw only a 12 amp current. 

In that sense, you can use only 8 outlets on a 14-wire gauge.

However, there is no specific information about the number of outlets to be put in a 15 amp circuit.

But eight is a standard number. Using more than eight can overload the circuit and trip it off.

12 wire gauge

If you have a 20 amp circuit, you are allowed to put 12 wire gauges in this circuit. A 20 amp circuit is allowed to draw 16 amps. 

In that sense, you can use only 10 outlets in the circuit. 

As mentioned earlier too, there is no specific number mentioned anywhere.

But, adding 10 outlets in a 20 amp circuit and using a 12 wire gauge is the right thing to do.

Uses of the wires

Though 12 wire gauge is better than 14 wire gauge, you can use both in different circumstances.

12 gauge wire

There is no specific usage of 12 wire gauge anywhere. 

However, they are good for kitchens, bathrooms, outdoor receptacles, and 120V air conditioners supporting 20 amps. 

Depending on the height, you can use a 12-wire gauge up to 70 feet on a 15 amp circuit.

On a 20 amp circuit, you can use up to 50 feet only.

The higher the amp, the lower the height.

14 wire gauge

A 14 copper wire gauge is ideal for lights, fixtures, and lighting circuits connected to a 15 amp circuit.

It would be best to use wires depending on the number of outlets added to the circuit.

A 14-wire gauge is not very flexible. So, it may be difficult for the wire to hold heavy equipment for a long time. 

Besides, a 14 copper wire gauge will measure around 1.63 mm, which means high resistance and overheating due to more current flow.

Common wire gauges

Wire color

Wire gauges come in different numbers and sizes.

Different wires are used for different purposes, depending on how much current is flown. 

Some common wire gauges are:

  • 14 wire gauge
  • 12 wire gauge
  • 10 wire gauge
  • 8 wire gauge
  • 6 wire gauge
  • 2 wire

There are some other gauges too.

And as I said, different gauges have different usages.

Below are some wire gauges and the right amperage for them:

  • 18 wire gauge for low voltage lights and lamp cords in the 10 amps
  • 16 wire gauge for light duty extension cords in a 13 amp
  • 14 wire gauge for light fixtures, lamps, and light circuits in 15 amps
  • 12 wire gauge for kitchen, bathroom, outdoor outlet, and 120V air conditioners in 20 amps
  • 10 wire gauge for electric cloth dryers, 240V window air conditioners, and electric water heaters in 30 amps
  • 6 wire gauge for cooktops and ranges having 40-50 amp circuits.
  • 4 wire gauges for electric furnaces and large electric heaters carrying 60 amps.

Final thoughts

The easiest way to identify a 12-wire gauge and a 14-wire gauge is by thickness. 

The 12-wire gauge measures 2.05 mm, whereas the 14-wire gauge measures 1.63 mm. So, the 12-wire gauges are quite thicker than the 14-wire gauges.

You can also feel the difference by weighing the wires. Since the 12-wire gauges are thicker, they have more mass and weigh more than the 14-wire gauges. 

The 12-wire gauges are stronger compared to the 14-wire gauges. 

So, these are the common ways to learn if the wire is 12 gauge or 14 gauge. 

The 12-wire gauges can be used in 20 amp circuits. But you should not use 14 wire gauges higher than 15 amp circuits. 

Though both wires have their purposes and benefits, 12-wire gauges are considered the best.

Data Source: National Electrical CodeElectrical wiringHome wiring.