Can I Connect 14 Gauge Wire To 12 Gauge Wire?

When planning out the electrical wiring in your home or replacing old wiring, you may have a number of questions. The main one being, can you mix gauge wiring on a single circuit? More specifically, can you connect 14-gauge wire to 12-gauge wire?

While this is possible, it is not recommended in order to prevent overloading. Also, the gauge wire depends largely on the size of the breaker that supplies it.

For example, if the amp capacity of your breaker is 20 amps, you should only use 12-gauge wire, and if it’s 15 amps, the entire circuit should be 14-gauge. While you can use 12-gauge on a 15-amp circuit, it’s not recommended, and you should never use a 14-gauge wire on a 20-amp circuit.

This may sound like a lot of information to digest; however, we’ll examine the reasoning behind this further and outline some other common electrical mistakes to avoid making as a homeowner.

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When shopping for electrical wire, I’m sure you’ve noticed that they come in a wide variety of sizes and types. While different types of wire are intended for different uses, understanding the right size wire, or gauge, you need is essential to making the correct choice.

Electrical wire is given its size specifications by the American Wire Gauge (AWG) system. Wire gauge refers to the physical size of the wire and is rated using a numerical designation.

This designation is in opposition to the diameter of conductors. More specifically, the larger the diameter of the wire, the smaller the gauge number. The most common sizes include 2-, 6-. 8-, 10-, 12-, and 14-gauge wire. The wire’s gauge will determine the amount of current that is permitted to pass through it safely.

When it comes to the electrical current, this is measured using ampacity. There is a maximum safe carrying capacity for every wire gauge on the market. Refer to the table below for the amperage capabilities of standard non-metallic (NM) cable:

Your circuit breakers and fuses offer good protection against the possibility of overheating or overloading wires, but they do not provide complete protection. Both devices are constructed to sense overloads in the current and will react by tripping or “blowing” before the wires reach a dangerous point of overheating.

It’s important that you safeguard against exceeding the amperage rating as both your fuses and circuit breaker are not completely foolproof. The potential for danger is presented anytime you plug an appliance or device that will draw more power than what the wire gauge is capable of.

For example, if your space heater is rated for 20 amps and you plug it into a 15-amp circuit that has been wired with 14-gauge wires, this poses a significant hazard. If your circuit breaker happens to fail or operate incorrectly, your heater is going to draw more power than the wires can handle. This will effectively heat the wires and could end up melting insulation nearby or setting any other surrounding materials ablaze.

However, on the other hand, it is perfectly safe to plug appliances that have a lower electrical load into circuits with a higher amperage rating and heavier gauge wires. It will simply draw only the current that is necessary and nothing more.

Now that we have a better understanding of wire sizing, amperage capacities, and why wire gauge is so important, let’s dive further into this question.

In order to prevent overloading or to overheat the wires, it is always recommended to use the same gauge wire throughout a circuit. Also, take special care to ensure that you’re using the correct gauge for the number of amps in the circuit. You can refer to the table above as a general guide.

Also, don’t simply proceed by visually looking at the wires. It’s important that you know their particular amp capacity and, contrary to logic, the smaller the gauge, the thicker the wire will be.

The amp capacity for 12-gauge wires is 20 amps. While you can technically use 12-gauge wires on 15-amp circuits, it is not recommended because of the greater cost of a larger size wire. Also, keep in mind that the amperage capacity for 14-gauge wires is 15 amps, and you should never use 14-gauge wires on 20 amp circuits because the wire will catch fire or melt before the breaker ever trips.

The gauge of wire you use depends on what exactly is on the circuit you’re connecting to. For instance, if you have both lights and outlets, you should use a 12 gauge. Or, if you are unsure of which gauge to use, then a 12 is a great choice as you cannot really go wrong with it.

However, a 12 gauge wire is not as flexible as a 14 gauge, and it is a little bit more expensive. But if you want to err on the side of caution, then 12 gauge is always a safe choice, especially if it’s on a 15 or 20 amp circuit.