What Wire Size for 50 Amp Breakers? (Explained)

Standards are in place to determine the safe wire size for 50 amp breakers. Whether you are adding a new circuit or need to rewire an old circuit, it’s important to get the right wire size for your needs.

According to the American Wire Standard (AWS), a 50 amp circuit breaker requires a 6-gauge copper wire. For long wire lengths, a larger wire, like 4-gauge aluminum wire, is often more cost-efficient. Using the right wire size helps prevent overheating and reduces the risk of electrical fires.

Current or amperage flowing through a conductor generates heat. The amount of current a wire can withstand before it gets too hot depends on the type of metal used as a conductor and the thickness of the wire.

The current flowing in a 50-amp circuit is considerably high, making the correct conductor wire choice even more critical when wiring your home electrical system.

wire size for a 50 amp breaker
What Wire Size for 50 Amp Breakers? (Explained) 6

Wire Size for 50 Amp Breakers Explained

According to the American Wire Gauge system, the appropriate wire gauge to use in conjunction with a 50-amp breaker is a 6-gauge wire. The 6-gauge copper wires are rated up to 55 amps, making it a good choice for this circuit.

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Electrical wires have three parts, the plastic sheath, the insulation around the metal conductor, and the conductor wire itself. When a wire is measured to establish the gauge, only the thickness of the metal conductor is measured. The metal conductor is the only section that will carry the current.

A 50-amp circuit in your home is intended for use with medium-heavy usage electric appliances. Household appliances in this category include electric stoves, ovens, washing machines, dishwashers, electric heaters, and hot tubs.

The thickness of a 6-gauge wire is 0.1620 inches or 4.115mm, but the wire gauge is generally clearly marked on the cable’s outer sheath. The central core of wires for 15, 20, and 30-amp circuits, 14, 12, and 10-gauge, respectively, is typically a solid core cable. The lower the AWG wire gauge number, the thicker the central core conductor becomes. Thick wires are not flexible, which poses problems when threading the cable through ducting.

A stranded core is typically used in thicker gauge wires to add flexibility to the cable. This flexibility makes installing the thicker gauge wire through ducting or conduits a much easier task.

The American Wire Gauge system standardizes the ratings for conductors with a copper conductor core. Some circuits contain an aluminum core conductor wiring, which changes the wire gauge required for a 50-amp circuit.

If your circuit wiring has an aluminum conductor, you need a wire of at least 4-gauge for compatibility with a 50-amp circuit breaker.

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You can use aluminum where cable weight and cost are factors since the aluminum cable is significantly lighter and cheaper than the copper equivalent. Many older homes use aluminum wiring, but most modern homes use copper core wires which are 61% more efficient for electricity transmission.

Certain appliances in the home require dedicated 50-amp circuits to which no other appliances are connected. The electric water heater in your home is a prime example of this type of appliance.

50-amp circuits have a current limit and limit the number of watts the circuit can support. The total watts for all the devices and appliances connected to the 50-amp circuit must not exceed 80% of the calculated wattage.

Most 50-amp circuits in a home utilize 240 volts instead of 120 volts for circuits that power smaller appliances.

The calculated wattage of a 50-amp circuit is 12000 watts at 240 volts. The maximum wattage allowed on the circuit is 80% of this total, which for a 50-amp circuit comes out to about 9600 watts. You can check you are not exceeding this limit by checking the watts of each household appliance connected to the circuit and totaling the watts. The total watts of the appliances must not be greater than 9600.

aluminum wires lg
What Wire Size for 50 Amp Breakers? (Explained) 7

6-Gauge Wire Size for 50 Amps

When installing an electrical circuit in your home or extending circuits, it is prudent to stay within the safety standards recommended for the electrical current the circuit will carry.

6-gauge wire is rated to handle up to 55 amps, which means it can handle a 50-amp current or a 50-amp circuit breaker without issue. For this reason, the Amerian Wire Gauge system stipulates a 6-gauge wire for use on a 50-amp circuit.

A 50-amp circuit seldom carries a current flow exceeding 50 amps; if this event occurs, the circuit breaker will trip. There is less resistance in a 6-gauge wire for fewer than 50 amps, meaning the electrical cable stays cooler and safer.

The National Electrical Code (NEC) puts a circuit breaker’s maximum continuous current capacity at 80% of its rating. This regulation means that a 50-amp circuit should only carry a maximum continuous load of up to 40 amps.

This 40-amp load is well within the limitations of a 6-gauge wire rated at 55 amps.

Distance and Voltage Drops

Electrical flow over long distances causes a significant voltage drop. You can offset the voltage drop with a larger gauge wire. Many electricians will use a 4-gauge aluminum wire for longer distances to reduce voltage drops.

While you can run a 6-gauge wire up to 188 feet, copper wire is more expensive per foot than aluminum wire. Therefore, most electricians will opt to run larger gauge aluminum wire instead.

For example, a 6-gauge wire size for 50 amp sub panel 100 feet away is sufficient. Here is a 240-volt distance and wire size for 50 amps.

Wire GaugeDistance
4 AWG218 feet
6 AWG188 feet
8 AWG152 feet
10 AWG128 feet

4-Gauge Wire Size for 50 Amps?

As stated above, copper wiring is best for 50 amps, but it can be expensive. It’s cheaper to use a larger gauge wire. A 4-gauge aluminum or copper-clad wire can safely handle the higher voltage, is lightweight, is more flexible, and will save money.

8-Gauge Wire Size for 50 Amps?

A copper conductor’s conductivity is affected by ambient temperature. Up to a point, the higher the temperature, the higher the flow of current the wire can handle.

An 8-gauge wire can handle a current of 50 amps at a temperature of 90 Celsius or 194 Fahrenheit. This temperature would be sufficient to melt or compromise the insulation around the conductive core, which is why the AWG works according to the 60 Celsius standard. Up to this temperature, the 8-gauge wire can carry 40 amps.

This temperature aspect is the reasoning behind placing a limit of 40 amps on an 8-gauge wire in the domestic electrical wiring environment. The PVC insulation typically insulates domestic electrical wiring and has a melting point of 70 Celsius or 158 Fahrenheit.

The melting point of the insulation gives a 10-Celsius temperature window on the rated current draw at 60-Celsius for the 8-gauge wire.

10-Gauge Wire Size for 50 Amps?

There is a difference between the current load that a bare copper wire can carry and an insulated copper wire of the same gauge.

A thinner wire, like a 10-gauge copper wire, can carry a 50-amp load, but the electrical resistance in the cable will cause overheating. The heat generated causes the insulation to melt, resulting in short circuits and potential shock and fire hazards.

The NEC stipulates that all electrical wiring must be insulated for domestic purposes. Consequently, the maximum current rating for insulated 10-gauge wire is 30 amps.

Conclusion

The regulations of the NEC standards for wire size for 50 amps are laid out by the AWG are the results of experimentation and testing, considering many different factors. The primary goal of these restrictions is to improve the safety of electrical wiring systems in domestic and commercial applications.

After reviewing the locations and circumstances under which the wiring is implemented in our dwellings, these regulatory bodies build safety buffers into their recommendations.

Staying within the wire size for 50 amps given by the NEC and the AWG ensures your electrical system will be safe and capable of delivering reliable power to your home.

The requirement to stay within code is to use a 6-gauge wire on a circuit with a 50-amp breaker installed.

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Hubert Miles

I've been conducting home inspections for 17 years. I'm a licensed Home Inspector, Certified Master Inspector (CMI), and FHA 203k Consultant. I started HomeInspectionInsider.com to help people better understand the home inspection process and answer questions about homeownership and home maintenance.
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