Most homes use 15 or 20A breakers. Therefore, most homeowners must identify a suitable wire size for their 15A breaker. Even though only five amps separate 15 and 20A breakers, they are not interchangeable.
In other words, a cable that supports 15A breakers won’t necessarily work on a 20A breaker. Keep this in mind before you undersize your wires. Finding the correct wire size for 15A breakers is no different from finding the wire size of any application.
What Size Wire Is Needed For 15 Amp Breaker?
A 15A breaker has a rating of 15 amps. 14AWG can withstand 15 amps.
Therefore, you wouldn’t be wrong if you decided to wire a 15A breaker with 14-gauge cabling. This method sounds so simple that it may raise suspicions among some homeowners. They are accustomed to consulting licensed electricians when buying electrical wiring.
And that habit is not bad. Anyone can find the correct cable size for a 15A breaker. Electricians stand out because they consider other factors when selecting the wire size.
The breaker size is not the only relevant variable. A qualified contractor will also account for the distance, ambient temperature, setting, etc. You should only rely on online tables when you can’t access a contractor.
Some people may encourage you to use 12AWG instead of 14AWG, which makes sense. 12AWG carries 20 amps.
In other words, it is more than capable of withstanding the demands of a 15A circuit. People use 12AWG wiring in 20A circuits. Where possible, you should install the thickest conductors you can find.
The objective is to lower the resistance, which, in turn, prevents overheating. But if the thickest conductors are the safest options, why do people use 14AWG instead of 12AWG?
12AWG is the best option. However, the price of the cable concerns them. Thicker wires are more expensive than their thinner counterparts.
If that wasn’t the case, everyone would purchase 0AWG for every application to eliminate overheating concerns. Homeowners with 15A circuits prioritize 14AWG because they want to limit their wiring expenditure.
Why spend more money on 12AWG when 14AWG is more than adequate for the task at hand? Additionally, 14AWG is more flexible. Like the price, stiffness tends to increase with thickness.
14AWG conductors are lighter and easier to handle than their 12AWG counterparts. But if that is true, why do some homeowners choose 12AWG for 15A over 14AWG?
First of all, they can afford it. If you have the financial strength to buy 12AWG, you should do so. Even though 12AWG is stiffer and more challenging to install, those inconveniences shouldn’t stop you from enjoying the versatility of the wire size.
Speaking of versatility, 12AWG gives you more room to breathe. A 15A breaker is supposed to trip when the current flowing through the 14AWG wire exceeds 15 amps.
But if things go wrong and the 15A breaker fails to respond, the 14AWG cable will overheat, starting a fire. This is where 12AWG shines. It can withstand more current than 14AWG without overheating.
With all those factors in mind, which wire size is the best for you? You can’t really go wrong with either option. Your pocket will decide. If you can afford it, buy 12AWG. If you want to save money, 14AWG is perfectly acceptable.
Although, if you prefer 12AWG to 14AWG, you might as well upgrade your system from 15A to 20A.
15A Breaker Wire Size Compatibility
Keep in mind that the data above doesn’t account for factors like distance, material, and temperature that influence a wire’s ability to carry electricity without overheating.
What Does Code Say About It?
The NEC expects 14AWG conductors to withstand 15 amps. Therefore, they do not oppose the idea of 14-gauge cables accommodating a 15A breaker.
Does Distance Matter While Choosing Wire Size For 15A Breaker?
For Copper Wire,
Distance is the one variable consumers rarely consider. They are smart enough to recognize the importance of the temperature rating and material, but not distance.
They forget that distance influences length, and the length is directly connected to the resistance a current encounters as it passes through the conductor. Longer wires are more susceptible to overheating because they have more resistance.
This encourages some homeowners to use 12AWG instead of 14AWG. You can lower the resistance and voltage drop by using a shorter cable. But what if that isn’t an option?
What if the conductors are expected to cross a long distance to reach their destination? Your only option is to use a thicker wire, such as 12AWG, that can deliver the power you need without overheating or plaguing your applications with debilitating voltage drops.
Don’t be afraid to raise the gauge, especially when you need longer wires. Admittedly, longer cables with higher gauges are more expensive. But that expense is worth it to prevent overheating, and significant voltage drops.
Voltage Vs 15 Amp Wire Size
Things To Consider To Determine Correct Wire Size For 15 Amps Breaker
In an ideal situation, you would ask an expert to select wires for your 15A breaker. But if this isn’t an option, and you have to choose the cables yourself, the following factors will influence your decision:
1). Try to select the thickest wire you can find. Any conductor larger than 14AWG can withstand 15 amps. Naturally, thicker lines have their limitations. For instance, they are more challenging to install. But if you have the means, wire sizes greater than 14AWG are the best option.
2). The material plays a critical role. I want you to know that aluminum’s conductivity is just 61 percent of copper’s conductivity.
Therefore, aluminum and copper wires are not equal. You can’t replace 14AWG copper with 14AWG aluminum on a 15A circuit. 14AWG aluminum can withstand fewer amps than 14AWG copper.
Therefore, if you want to replace 14AWG copper with aluminum, aim for 12AWG. Otherwise, the 15A circuit may overwhelm your 14AWG aluminum lines, especially when a surge occurs.
3). Distance and wire size go hand in hand. Because copper is more conductive, it can cross long distances while keeping the voltage drop and resistance in check.
12AWG copper wires can traverse 52 feet on a 20A circuit, whereas aluminum lines of a similar size are restricted to 33 feet.
4). The setting matters because copper is more robust than aluminum.
Therefore, you can trust copper to survive the wear and tear exerted by rugged environments. Admittedly, aluminum can deliver the same stability and durability if it has sufficient protection. But armored aluminum cables are expensive.
Remember that many people use aluminum because it is cheaper than copper. Spending more money on armored aluminum cabling is pointless when you can buy copper alternatives that are not only more durable but also more conductive.
5). Laypeople that perform their own wiring tend to gravitate towards aluminum because the material is lighter and easier to install.
Wire Size For Double Pole 15 Amp Breaker
14/2 is a suitable wire size for a 15A double pole breaker.