125 Amp Wire Size and Breaker Guide

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Hubert Miles

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Regarding electrical wiring, the 125 amp wire size and breaker are essential components for a safe and reliable system. Knowing the right wire size and the appropriate amp breaker is critical to ensure that your electrical system is up-to-code and can handle all your power needs.

The 125 amp wire size necessary to carry 100 amps to a 125 amp subpanel at 75 degrees Celcius 200 feet away from the main panel is a 1 AWG copper wire or a 2/0 AWG aluminum wire. The National Electrical Code (NEC) helps set electrical standards to protect against potential overloads, short circuits, and arc faults.

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125 Amp Wire Size and Breaker Overview

With this 125 amp wire size and breaker guide, you’ll be empowered to ensure your system is up-to-date and able to handle all of your electrical needs.

So don’t risk it; take the time to think through your electrical project from start to finish, and you’ll be sure to get the power you need without any safety risks or costly mistakes.

  • Always use the 125 amp wire size specified by the National Electric Code for the amps in your circuit. Be sure never to use a smaller gauge wire than what is recommended.
  • When using a 125-amp circuit breaker, 1-gauge copper or 2/0 aluminum wires must be used as the conductors.

By following these guidelines, you’ll have peace of mind that your 125 amp wire size and breaker are up to code and can handle all of your electrical needs. With the proper installation, you won’t have to worry about arcing or short circuits, which can be a major safety hazard.

Please consult a licensed electrician for more detailed information on the 125 amp wire size and breaker. With their expertise, you can rest assured that your electrical system is up-to-code and safe!

125 amp wire size

What 125 Amp Wire Size You Need

When determining the 125 amp sub panel wire size, there are two types of 125 amp wire sizes: 1-gauge copper and 2/0 aluminum. Both have their own advantages, depending on your individual needs.

1-gauge copper is the most common type of wire used in residential and commercial circuits for up to 125 amps. Copper is the best option and provides superior conductivity, meaning it can efficiently handle higher electrical current demands.

2/0 aluminum is another popular 125 amp subpanel wire size. It costs less money than 1-gauge copper, is lightweight, and has excellent flexibility making it cost-effective for longer distances.

No matter what type of 125 amp wire size you choose, consult a certified electrician for help with the installation and use the size specified by the NEC table for your circuit.

When wiring a 125-amp system, select a 125-amp double pole circuit breaker for a main disconnect. Double pole breakers are rated for 240 volts and provide greater protection against short circuits, arc faults, and overloads.

The wire will have two hot wires, one neutral wire, and one ground wire, regardless if you select 1-gauge copper or 2/0 aluminum.

125 Amp Wire Size for Long Distances

If you’re running a 125 amp circuit for longer distances, such as between two buildings, it’s important to select the correct wire size. For long distances, you’ll need a thicker wire to counteract voltage drop and ensure that the circuit works properly at the end of the line.

CopperAluminumMaximum Distance
1 AWG2/0 AWG200 feet
1/0 AWG3/0 AWG250 feet
2/0 AWG4/0 AWG300 feet
3/0 AWG300 kcmil400 feet
Parameters 230 Volt, Three-phase, 3% voltage drop, 75 degrees C

Aluminum vs Copper Wires

The two main differences between aluminum and copper wires are their resistance to heat and voltage.

Aluminum wires have lower heat resistance so they can be used for relatively high-voltage applications. Because of the lower heat resistance, aluminum wires can heat up more quickly than copper wires, which is why they must be thicker to carry the same voltage.

On the other hand, copper wires are better at maintaining consistent electrical flow at higher temperatures and offer better conductivity than aluminum wires.

Therefore, a smaller wire size can safely carry the maximum current from the main circuit breaker panel to the new sub panel or appliance. Copper wire material is better for branch circuits to lighting, outlets, and household appliances.

The downside of copper wiring is that it is expensive, especially in larger wires that run long distances. This makes aluminum wire a more cost-effective choice for 125 amp feeder wire, despite the thickness of the wire.

When choosing between aluminum or copper wiring, it’s important to consider the purpose of the wiring and the environment in which it will be used.

Copper wires are typically more expensive than aluminum but are better suited for long runs or high-heat environments.

Aluminum is often used as a cost-effective alternative when copper is not suitable. Ultimately, both types of wiring have advantages and a place in modern electrical work.

125 Amp Wire Size FAQs

Understanding the size of the wire is important when it comes to electrical wiring projects. When dealing with 125 amp wir sizes, many questions about its size and usage may arise. These are some frequently asked questions (FAQs) related to the wire size of 125 amps and how to properly use it in any electrical project.

What size breaker do I need for a 125 amp sub panel?

You need a 125 Amp 240-volt circuit breaker for a 125 amp breaker box. The main breaker will supply power and serve as a main disconnect for the new subpanel, giving it its own dedicated circuit.

What size wire is good for 120 amps?

The appropriate wire size is 1-gauge copper, or 2/0 aluminum wire for 120 amps. For distances longer than 200 feet, you should move up to 1/0 copper or 3/0 aluminum wire to counter voltage drop.

How many amps can a 125 amp panel handle?

A 125 amp panel can handle a maximum of 125 amps. According to the NEC code 80% guideline, the maximum electrical load calculation should not exceed 100 amps.

What size wire for 100 amp service 125 feet away?

To deliver 100 amp electrical service to a 125 amp subpanel 125 feet away at 75 degrees C, you need 1 AWG (American Wire Gauge) copper wire or 2/0 AWG aluminum wire. Some important factors can vary depending on the electrical project. A professional electrician should be consulted for any major wiring jobs.

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Hubert Miles

I've been conducting professional home inspections since 2002. I'm a licensed Home Inspector, Certified Professional Inspector (CPI), 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.
DISCLAIMER: The content published on HomeInspectionInsider.com is not professional advice. You should consult with a licensed professional and check local permit requirements before starting any project.
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