What is the Correct Wire Size for 80A Breaker and Load?

Electrical Technology

How to Determine the Suitable Wire Size for a 80A Breaker and Load Circuits Based on NEC?

An 80-amp breaker is typically used for high-demand devices such as large air conditioning units, electric vehicle chargers, and heavy-duty appliances. Proper wire size selection is crucial for safety, efficiency, and compliance with the National Electrical Code (NEC). In this article, we’ll guide you on how to determine the correct wire size for an 80A breaker, based on NEC standards.

According to NEC, the recommended wire size for an 80-amp circuit is #3 AWG copper or #1 AWG aluminum. However, factors such as voltage drop, distance, temperature, and insulation type also play a role. For specific projects, always consult a licensed electrician to ensure compliance with NEC and local regulations.

Related Post: What is the Suitable Wire Size for 70A Breaker and Load?

Factors Affecting Wire Size for an 80A Breaker

When determining the wire size for an 80-amp breaker, consider these factors:

Voltage Drop: As the length of the wire increases, so does the voltage drop. For wire runs longer than 50 feet, it’s advised to increase the wire size to minimize the voltage drop and ensure efficient power delivery.
Temperature Rating: The ampacity (current-carrying capacity) of the wire depends on the temperature rating of the wire’s insulation. For example:
- At 60°C (140°F), #3 AWG copper wire can carry 85 amps.
- At 75°C (167°F), it can handle 100 amps.
Wire Insulation Type: Common wire insulation types include THHN (Thermoplastic High Heat-resistant Nylon-coated) and THWN (Thermoplastic Heat and Water-resistant Nylon-coated). These materials provide better heat tolerance, which affects ampacity.

Table of Contents

Toggle

What is the Correct Wire Size for an 80A Circuit?

According to NEC Table 310.15(B)(16), the correct wire size for an 80-amp breaker is:

#3 AWG copper
#1 AWG aluminum

However, these values can be affected by the temperature and distance of the wire run. Copper wire is generally preferred for its higher conductivity and lower resistance compared to aluminum.

Both #3 gauge copper and #1 gauge aluminum conductors have the following ampacities at different ambient temperatures.

- 85-Amps at 60°C (140°F)
- 100-Amps at 75°C (167°F)
- 115-Amps at 90°C (194°F)

These values based on NEC Table 310.15(B)(16) illustrate that #3 AWG copper or #1 AWG aluminum is suitable for an 80A breaker. It is good to consider both ambient temperature and conductor material while selecting the wire size to counter the voltage drop.

Good to Know:

The correct wire size for an 80A breaker is #3 AWG copper or #1 AWG aluminum.
An 80A breaker is typically used for large, single appliances as a dedicated circuit.
In 120V circuits: Use 4-2 with ground wire for 80A breaker and load circuits.
In 240V circuits: Use 4-3 with ground wire for 80A breaker and load circuits.
In 240V with neutral: Use 4-4 with ground for 80A breaker and load circuits
You may use A 80A, 240V breaker as dedicated circuit for single unit only.
For long-distance runs (over 50 feet or 15.25 meters), consider upgrading to a larger gauge wire to compensate for voltage drop. The NEC recommends adding 20% more ampacity for every 100 feet (30.50 meters) of distance.

Selecting the Correct Wire Size for an 80A Breaker

Continuous Load Circuit

The NEC mandates that continuous loads should not exceed 80% of the breaker’s rating. For an 80-amp breaker:

80A × 80% = 64A

This means the breaker should not be loaded with more than 64 amps continuously. On the other hand, If your equipment has a Minimum Circuit Ampacity (MCA) of 64A, and you want to find the right size of breaker for 64-Amp continuous load circuit, the breaker should handle 125% of the load current amperes.

64A × 125% = 80A

Thus, a #3 AWG copper wire or #1 AWG aluminum wire can carry the necessary current up to 64-Amp safely.

Non-Continuous Load Circuit

For non-continuous loads, such as short-term operations, the breaker can handle the full 80 amps without any derating. In this case, both #3 AWG copper and #1 AWG aluminum wires are adequate for the load.

Good to Know: Always consider voltage drop in long run and ambient temperature when selecting the wire size.

How Many Amps Can an 80A Breaker Safely Handle?

According to NEC guidelines, an 80A breaker can safely handle:

64A for continuous load circuits (80A × 80% = 64A)
80A for non-continuous load circuits

This complies with NEC sections 210.19(A) and 215.2.

Good to know:

Use an 80A breaker for 64A continuous load circuits or maximum 80A non-continuous load circuits.
If the load circuit is greater than 60A, it will require a disconnect switch due to the absence of outlets and switches rated for 80A. (NEC 625.23 – 2011).

How Many Watts Can an 80A Breaker Hold?

To calculate the wattage for an 80-amp breaker, use the formula:

Watts = Volts × Amps

120V Circuit:

A 1-P, 80A breaker on a 120V circuit can hold:

80A × 120V = 9,600W … (maximum)
- Continuous load: 80A × 80% = 64A
- Safe Load: 64A × 120V = 7,680W

240V Circuit:

A 2-P, 80A breaker in a 240V circuit holds:

80A × 240V = 19,200W
- Continuous load: 80A × 80% = 56A
- Safe Load: 64A × 240V = 15,360W

You can safely connect up to 15,360 watts of load on a two pole, 80A breaker in a 240V circuit. As a result, you may only use a single load up to 80A per 90A breaker (NEC 210.23) or multiple load circuits in the subpanel where the total load amperes doesn’t exceed 80A.

Good to know: An 80A breaker can handle a maximum of 9,600W and safely 7,680W in a 120V circuit. Similarly, it can handle a maximum of 19,200W and safely 15,360W in a 240V circuit.

Related Post: What is the Correct Wire Size for a 40A Breaker and Load?

Suitable Cable Types for an 80A Breaker

When selecting a cable for an 80-amp breaker, the material and insulation type play key roles in ensuring the safe and efficient operation of the circuit. Below are the suitable types of cables for an 80A breaker:

Copper Wire:

- THHN (Thermoplastic High Heat-resistant Nylon-coated): THHN, suitable for both dry and wet environments, can withstand high temperatures of up to 90°C or 194°F. It’s commonly used in residential and commercial wiring.
- THWN (Thermoplastic Heat and Water-resistant Nylon-coated): This wire is ideal for wet locations, offering resistance to water and heat.

Aluminum Wire:

- XHHW (Cross-Linked Polyethylene High Heat-resistant Water-resistant): This insulation is highly durable. Hence, making it suitable for underground installations and high-temperature environments.
- USE (Underground Service Entrance Cable): This cable, designed for direct burial, is suitable for outdoor applications requiring moisture resistance.

MC (Metal-Clad Cable):

- MC Cable: Used in commercial and industrial settings, MC cables consist of copper or aluminum conductors inside a metal sheath, providing enhanced protection and flexibility in tough environments.

SE (Service Entrance Cable):

- Type SE Cable: Primarily used for delivering electrical power to residential and small commercial service panels, SE cables come with a rugged outer covering suitable for outdoor installation.

Applications of 80A Breakers

80-amp breakers are typically used as dedicated circuits or multiple circuits that require higher power levels. These breakers are common in both residential and commercial applications where large, power-hungry appliances and systems are used. Below are some key applications:

Main Panels in Homes: An 80-amp are used in the main electric panel to supply power to a single sub-circuits e.g. water heater element, dryer, electric stoves etc. or use to feed power to multiple branch circuits and outlets.
Subpanels in Workshops or Garages: 80A breakers are often used to feed subpanels in areas where multiple power-hungry tools or appliances are run, such as workshops, garages, or large home additions for better power distribution management.
Electric Vehicle (EV) Chargers: EV chargers, especially those rated for faster charging, often require higher amperage. An 80A breaker is suitable for high-powered Level 2 or Level 3 EV charging stations.
Air Conditioning and HVAC Systems: Large central air conditioning units, commercial HVAC systems, or heat pumps typically need 80-amp breakers to ensure sufficient current flow for startup and continuous operation.
High Power Lighting: An 80A breaker are commonly used for lighting fixtures and lighting control systems for large power lighting circuits such as concert venues, stadiums, and theaters.
Electric Furnaces and Water Heaters: High-powered electric furnaces, large electric water heaters, and tankless water heaters demand significant current. Hence, 80-amp rated breakers are suitable for these installations.
Commercial Kitchen Equipment: In commercial kitchens, electric ovens, large stoves, and other heavy-duty equipment frequently require dedicated 80-amp circuits to handle the high power demands safely.
Welding Equipment: Welding machines, especially in industrial settings, often require 80-amp circuits due to their high power consumption during operation.
Motors & Inductive Loads: Compressors, pumps, submersible and large inductive loads such as motors need high amperage to start and run the circuit. An 80-Amp dedicated circuit are used for such types of loads.
Data-centers: 80A circuits are used for high amperes date centers equipment and devices such as servers, inverters and fan cooling system.
Hot Tubs and Spas: Larger hot tubs or spas with advanced heating and jet systems may require 80A circuits to manage the power draw efficiently.

Good to Know:

Ensure the ampere rating of a receptacle does not exceed that of the branch circuit.
The calculations for breaker and wire sizes above apply only to purely resistive load circuits, such as lighting circuits.
For inductive loads like motors or HVAC systems, refer to NEC Article 440, especially sections 440.22 and 440.32. If unsure, consult an HVACR contractor or licensed electrician.
An 80A branch circuit requires #3 AWG copper wire or #1 AWG aluminum wire, according to NEC Table 310.15(B)(16) (formerly 310.16) and section 210.24.
An 80A breaker can support a 64A continuous load and an 80A non-continuous load, per NEC sections 210.19(A), 215.2, and 230.42(A).
It’s against code to use smaller wire gauges, like #4 or #6 AWG, instead of #3 AWG with an 80A breaker.
According to NEC 210.21(B)(3), it’s permissible to use two 40A or 50A outlets on an 80A circuit if there are multiple receptacles and only one is used at a time. The total load must not exceed 80A, such as when breakers feed branch circuits in a subpanel.
When installing an 80A circuit, dedicate it to a single appliance with a maximum load of 64A. Drawing more than 64A continuously will overheat the circuit and could cause serious injury or fire hazards.
Always consult a licensed electrician to ensure compliance with NEC standards and to verify the correct wire size for your specific installation.