The optimal 50 amp wire size is 6 AWG copper conductors, and 4 AWG aluminum conductors for a circuit breaker rated at 50 Amps for cable lengths less than 100 feet, a typical length for wiring associated with a 50 Amp circuit breaker. 1
Utilizing 8 AWG copper and 6 AWG aluminum conductors is generally not recommended, even though they fall within the 50 AMP to 60 AMP capacity range. This is because, as per the National Electrical Code (NEC), the maximum operational load of an electrical circuit shouldn’t surpass 80% of its capacity.
Consider the voltage drop for cable runs exceeding 100 feet. For a cable run of 200 feet, the recommended sizes would be a 4 AWG for copper conductors or a 2 AWG for aluminum conductors. 2
It’s important to note that the specific kind of circuit breaker does not influence the choice of wire size and type for a circuit breaker. Whether it’s a standard circuit breaker, an AFCI (Arc Fault Circuit Interrupter), or a GFCI (Ground Fault Circuit Interrupter), the same wiring specifications apply.
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.
50 Amp Wire Size & Circuit Breaker Explained
Let’s examine what gauge wire is for 50 amp 220v circuits.
According to the American Wire Gauge system, the correct 50 amp breaker wire size is 6 gauge. The 6 AWG copper wires are rated up to 55 amps, making it a good choice for this circuit.
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.
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 wire size in your home is intended for use with medium-heavy usage electric appliances. Household appliances in this category include electric stoves, ovens, select electric heaters, and hot tubs.
The thickness of a 6-gauge wire size 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 rating, respectively, is typically a solid core cable.
The lower the AWG wire gauge number, the thicker the central core conductor. 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 much easier.
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.
50 Amp Cable Types
For 50-amp circuits, selecting the appropriate cable type is crucial to ensure safety, efficiency, and compliance with electrical codes.
The cable type not only involves the material of the conductor (copper or aluminum, as previously discussed) but also the insulation and sheathing that protect the conductors. Here are some common cable types suitable for 50-amp circuits:
- THHN/THWN: THHN stands for Thermoplastic High Heat-resistant Nylon-coated. THWN is Thermoplastic Heat and Water-resistant Nylon-coated. These wires are commonly used in conduit or other recognized raceways for services, feeders, and branch circuit wiring.
- NM-B: NM-B stands for Non-Metallic Sheathed Cable, Type B. This cable is called “Romex,” after a popular brand. It consists of two or more insulated conductors and a bare ground wire, all enclosed within a non-metallic sheath.
- UF-B: UF-B stands for Underground Feeder Type B. This cable type is similar to NM-B but is designed for direct underground burial (without conduit) and damp or corrosive locations.
- SER: SER stands for Service Entrance Cable, Type SE, Style R. This cable has several insulated conductors (usually three or four) and a bare ground wire. The conductors are encased in an outer sheath.
- SEU: SEU stands for Service Entrance Cable, Type SE, Style U. It’s similar to SER but generally contains only two insulated conductors with a bare ground wire and is used in particular configurations.
- Mobile Home Feeder: This cable is designed to supply power to mobile homes as a service entrance cable. It has multiple insulated aluminum conductors and a bare aluminum ground wire, all encased in a sunlight-resistant outer jacket.
Copper vs Aluminum Wire Comparison
When considering copper versus aluminum wiring for a 50-amp circuit breaker, several key differences need to be taken into account:
Conductivity and Size
- Copper: Copper wire has higher electrical conductivity compared to aluminum. As a result, copper wires can carry more current than aluminum wires of the same size. For a 50-amp breaker, 6 AWG copper wire is generally recommended.
- Aluminum: Although aluminum wire has lower conductivity, it’s a cost-effective alternative. Due to its lower conductivity, a larger aluminum wire must carry the same current as a copper wire. For a 50-amp breaker, 4 AWG aluminum wire is typically used.
Durability and Tensile Strength
- Copper: Copper wire is more durable and has a higher tensile strength. This means it’s less likely to break under stress and can withstand more physical wear and tear.
- Aluminum: Aluminum wire is more malleable and less durable than copper. It’s also more prone to breakage under stress, which can be considered in environments where the wire may be subject to physical strain.
Expansion and Contraction
- Copper: Copper wire has a lower coefficient of expansion, meaning it expands and contracts less with temperature changes than aluminum. This property makes it more stable over time and under different temperature conditions.
- Aluminum: Aluminum wire expands and contracts more with temperature changes. This can lead to loosening connections over time, which can potentially cause overheating or electrical fires if not properly maintained.
- Copper: Copper wire is less prone to corrosion. When it does corrode, the resulting patina still conducts electricity well and doesn’t significantly degrade the wire’s performance.
- Aluminum: Aluminum wire is more susceptible to corrosion, especially when in contact with certain metals, leading to galvanic corrosion. This can increase resistance and potentially lead to overheating.
- Copper: Copper wire is generally more expensive than aluminum wire due to its higher conductivity, durability, and the overall cost of the material.
- Aluminum: Aluminum wire is a more cost-effective option and is lighter in weight, which can reduce overall costs in applications requiring large amounts of wiring.
- Copper: Copper wire is easier to work with due to its flexibility and tensile strength. Its connections are generally more secure and less likely to loosen over time.
- Aluminum: Special care must be taken when installing aluminum wire. It’s essential to use connectors compatible with aluminum and to ensure connections are tight to compensate for the wire’s tendency to expand and contract.
50 Amp Circuit Uses
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.
Residential Use Cases:
- Electric Ranges and Ovens: Many electric ranges and ovens require a 50-amp circuit to accommodate the high power needed for heating elements.
- HVAC Systems: Some high-capacity air conditioning units or heating systems demand significant power and may be connected to a 50-amp circuit.
- Electric Dryers: While many dryers can operate on a 30-amp circuit, some high-capacity or fast-drying models might require a 50-amp circuit.
- Hot Tubs and Saunas: Heating elements and pumps for hot tubs and saunas often require a lot of power, making a 50-amp circuit a common requirement.
- Electric Vehicle (EV) Chargers: As EVs become more common, homeowners might install Level 2 chargers that require a 50-amp circuit to reduce charging time.
- subpanels: In larger homes, a 50-amp circuit might feed a subpanel that distributes power to a specific area or set of appliances.
Commercial Use Cases:
- Commercial Kitchens: Restaurants and other food service businesses often use 50-amp circuits for high-powered cooking appliances like commercial ovens, grills, and deep fryers.
- Power Tools and Machinery: In workshops, garages, and industrial settings, 50-amp circuits may be required for heavy-duty power tools, machinery, or motors.
- Data Centers: Some equipment in data centers, like high-capacity servers or HVAC systems to cool servers, might require 50-amp circuits to handle the power load.
- Medical Equipment: Certain medical equipment in clinics or hospitals might require a 50-amp circuit due to their high power needs.
- Event Spaces: 50-amp circuits might power large speakers, stages, or lighting systems for live events, concerts, or conferences.
- HVAC Systems in Commercial Buildings: Large commercial buildings often have extensive heating and cooling needs, and 50-amp circuits may be used for large HVAC units or systems.
NEC 80% Rule For 50 Amp Circuits
A 50 amp wire size circuits have a current limit and limits 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 50a wire size 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.
Related reading: 70 Amp Wire Size: Breaker & Wiring Gauge Guide
6-Gauge Wire 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 AWG system stipulates a 6-gauge wire for use on a 50-amp circuit.
A 50a wire size 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.
What Gauge Wire for 50 Amp Circuits?
Electrical flow over long distances causes a significant voltage drop. You can offset the voltage drop with a larger gauge wire. Many electricians 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 a 50 amp sub panel 100 feet away is sufficient. Here is a 240-volt distance and wire size for 50 amps.
4-Gauge Wire Size for 50 Amps?
As stated above, a copper conductor is best for 50 amps but can be expensive. It’s cheaper to use a larger gauge wire. A 4-gauge aluminum or copper-clad wire size can safely handle the higher voltage, is lightweight, is more flexible, and will save money.
8-Gauge Wire Size for 50 Amps?
Copper wiring conductivity is affected by ambient temperature. Up to a point, the higher the temperature, the higher the flow of current the wire can handle. Let’s discuss can 8 gauge wire handle 50 amps.
An 8-gauge wire size 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 wire size 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 with 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 AWG copper wire size, 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.
Wire Gauge for 50 Amp FAQs
Will 8 gauge wire carry 50 amps?
While an AWG wire can carry a 50 amp load a shorter distance, it’s best to use a 6 gauge wire size for 50 amps. 8 gauge is better suited to carry 40 amps.
What size wire do I need to run 50 amps 100 feet?
To run 50 amps 100 feet, you will need to use 6 AWG (American Wire Gauge) wire.
What size wire do I need for a 50 amp underground service?
You must use a #4 AWG copper wire for a 50 amp underground service to account for distance and voltage drop.
Will 10 gauge wire carry 50 amps?
No, a 10 gauge wire is not suitable for carrying 50 amps. The American Wire Gauge (AWG) system indicates that a 10 gauge wire is only suitable for carrying up to 30 amps.
What wire for 50 amp breaker?
6 AWG copper wire is typically used for a 50 amp breaker.
What wire size for 50 amps 240 volts?
6 AWG wire size is best for 50-amp 240-volt appliances and subpanels.
Related reading: 80 Amp Wire Size: Breaker & Wiring Gauge Guide