What Size Wire Do You Need for a 50-Amp Breaker? (Explained)

When installing a new circuit in your home or rewiring an existing circuit, it is vital to choose the correct conductor. Standards are in place to determine which wire sizes are safe and appropriate for various current sizes. So what size wire do you need for a circuit with a 50-amp breaker?

According to the American Wire Standard (AWS), a 50-amp circuit breaker requires a wire of at least 6-gauge as the conductor for the circuit. Using a thinner wire gauge will result in your electrical system not being up to code and can pose a severe safety risk.

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 correct conductor wire choice even more critical when wiring your home electrical system.

x
Why Home Inspections Are Important
What Is The Appropriate Wire Size For a 50-Amp Circuit Breaker?

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 conductor wire is rated up to 55 amps, making it the perfect choice for this circuit.

Electrical conductor wire consists of 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.

The intention of a 50-amp circuit in your home is for use with medium-heavy usage electric appliances. 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 cables 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 some 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.

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 appliance connected to the circuit and totaling the watts. The total watts of the appliances must not be greater than 9600.

Can 6-Gauge Wire Handle 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 current the circuit will be carrying.

6-gauge wire is rated to handle up to 55 amps, which means it has ample capacity to 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 will seldom carry a current exceeding 50 amps, and if this event occurs, the circuit breaker will trip.

The National Electrical Code or 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 be carrying 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.

Can 8-Gauge Wire Handle 50 Amps?

A copper conductor’s conductivity is affected by temperature. Up to a point, the higher the temperature, the higher the 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 used to insulate domestic electrical wiring 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 at 60-Celsius for the 8-gauge wire.

Will 10-Gauge Wire Carry 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 10-gauge bare copper wire can carry a 50-amp load, but the resistance in the cable will cause it to heat up substantially. It is this heat generated by the current that causes a problem for insulated cables. The heat causes the insulation to melt, resulting in shortcircuits and potential shock and fire hazards.

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

Conclusion

The regulations of the NEC and the standards laid out by the AWG are the results of experimentation and testing, taking into account many different factors. The primary goal of these restrictions is to improve the safety of electrical wiring systems in both 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 parameters 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.

Sources

HomeInspectionInsider.com is owned and operated by Hubert Miles is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. HomeInspectionInsider.com also participates in affiliate programs with other affiliate sites. Hubert Miles is compensated for referring traffic and business to these companies.

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.

Recent Posts