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100 Amp Sub Panel Wire Size? (All You Need to Know)

Generally, a 100 amp service panel can provide power for a medium-sized home that includes multiple 240 Volt electronic appliances and air conditioning units. 

In today’s article, we will discuss the wire size for the 100 amp sub panel and every other thing that you need to know. 

Determining the wire size for 100 pumps up panel is very important because this will help you to provide the proper power electricity output through the wire.

Generally, when you plan to set up a 100 amp sub panel as a conduit circuit you will need to make sure that you choose the right type of wire for the circuit so that it can handle up to 24,000 watts of electricity at 240 volts.

Generally, it is recommended to use #4 copper wires for a 100amp sub panel. Below is a brief discussion on the Ampacity and gauge of 100 amp subpanel wire size: 

Ampacity: 

When running the subpanel, you should never put the circuit under 100% ampacity. It is ideal to wire the circuit to hit 80% ampacity. Generally, the #4 AWG has 85A ampacity but should conduct at most 68 amps.

Gauge: 

When choosing the wire for a 100 amp subpanel, you need to make sure that the wire gorge is sufficient for the amperage of the sub panel. Generally, a 100 amp sub panel requires #4 copper wires or #2 aluminum wires.

100 amp sub panel wire size:

Generally, the wire that is suitable to run a 100amp subpanel is #4 copper wires or #2 aluminum wires. You should make sure that the wire you are using to run 100 amps up panel should be sufficient to the amperage of the sub panel to provide you with proper electricity flow.

Generally, wiring is one of the most essential parts of electrical work that is being done to ensure proper power supply throughout the house. You need to choose the right type of wire for your electrical sub panel.

Because choosing the wrong wire may not be able to suit the electric flow and cause a lot of nuisances. In addition to that, you should always follow the NEC rule when choosing the wire for a sub-panel.

The NEC rule provides us with the proper guideline regarding any electrical work and eases the effort. Generally, the NEC rule indicates that the wire should not hit more than 80% of its electric supply.

Considering that, you need to follow the rules and regulations properly to power your house using a 100 amp sub panel. There is a variety of wires available to use in a 100 amp sub panel.

However, the ideal and recommended wires for the 100amp sub panel to power up a medium-sized house is the #4 AWG or #2 AWG aluminum wire.

Generally, these two wires have the amperage and Gauge rating that is ideal and suitable for the sub panel. When installing the #4 AWG copper wire in the sub panel, you should take the necessary steps to secure the wire from any unwanted occurring.

The wire must go inside a minimum of 1.25 inches, and schedule 40 or 80 PVC electric conduits for underground service.

However, some people recommend using the #2 AWG aluminum wire for the 100 amps sub panel because it has a lower conductivity than copper wires. In addition to that, the aluminum wiring requires a larger diameter wire.

That is why you’ll need a #2 gauge wire for both aluminum and copper-clad aluminum wire to power up a 100 amps sub panel easily.

Following the NEC or national electric code, the rule is important when installing a 100 amps sub panel in your house because the NEC rule will be able to provide you with the right sized wire and amperage it to operate with the sub panel.

Below is a brief discussion on what the NEC rule describes when it comes to choosing the right sized wire for a 100 amps sub panel:

NEC code for wire size: 

Generally, there are a few factors that are needed to be determined when you choose the wire size for the 100 amps subpanel. The National Electric Code for the Wire used in 100 amps subpanel should hit 80% of the requirement.

Generally, the 4 AWG can handle 85 amps of power supply. It is highly recommended to maintain maximum loading for any branch circuit that should not be more than 80% of the ampacity.

In addition to that, you might need to increase the amps by 20% for every 100 feet of distance from the sub-panel because the voltage can inevitably drop in the circuit.

Following the NEC rule for the 100 amps, the sub-panel will help you to determine the right type of wire for it.

Wire size for 100 amp sub panelDistance/Length of wire
#4 AWG wire100 feet away
#0 AWG wire150 feet away
#3 AWG wire200 feet away
2/0 AWG copper wire400 feet away

How to determine a 100 amp sub panel wire size?

Generally, it is important to choose the right size wire for the electrical works so that the wire can help you to provide proper electric output to your house.

If you do not choose the right sized wire, it can cause a burn to the circuit and even damage to the household appliances as well. Generally, most people tend to have a 100 amp sub panel in their house which can provide them with 24,000 watts at 240 Volt.

However, using a 100 amps sub-panel, you can run all the household appliances for a medium house, including a central air conditioning unit.

That is why it is important to choose the right size wire for a 100 amps sub panel. However, in the United States, the AWG gauge system is used to determine the wire size.

However, the wire size can range from 0000 with 230 ampacities to the smallest of 40 AWG with less than 0.1 ampacities.

Generally, some factors are considered when it comes to choosing the right sized wire for the sub-panel because due to temperature the length of the wire can vary.

In addition to that, you also need to keep in mind the distance because there is a chance that the voltage can drop when coming inside the circuit.

Below is a brief discussion on a few factors that are needed to determine for 100 amp subpanel wire size: 

Temperature: 

Temperature is one of the most common factors that is determined when choosing the wire for 100 amps sub panel. Generally, due to temperature changes, the effectiveness of the wire can change. 

Distance: 

Another thing that you need to keep in mind when considering the wire size for 100 amps sub panel is the distance because when you connect the wire from the sub panel to the circuit there should be some voltage drop in the circuit. 

NEC rule: 

The best way to determine the wire size for a 100 amps subpanel is to follow the NEC rule. Generally, the NEC rule provides you with all the necessary information that is required to select the wire for 100 amps sub panel.

Why Is wire size important?

The wire is considered one of the most effective and important parts of electrical works. Whenever you do any electrical job, you need to make sure that you choose the right type of wire so that it can provide you with maximum output.

In addition to that, the wire helps to provide the electrical flow smoothly from one place to another, so that electrical issues can be reduced.

Generally, we run a variety of appliances in our homes. Below is a brief discussion on why is wire size important in electrical works: 

Ensure uninterrupted electric flow: 

One of the main reasons why the wire size is important is because the wire runs large and small household appliances. That is why to ensure uninterrupted electric flow, the wires need to be precise. 

To avoid high resistance: 

Due to high resistance, the wire can generate heat and turn into a fire risk. That is why the wire needs to be accurately measured. 

Safety reasons: 

Finally, the last and most important thing about the wire size is the safety reasons that ensure some safety when electricity flows through the wire.

Sub panel wire size & Amp rating chart:

Amp ratingAluminum wire gauge size (AWG)Copper wire gauge size (AWG)
125 amp1/01/0
100 amp1/02
60 amp36
50 amp46
40 amp68
30 amp810
20 amp1012

Final thoughts

Generally, it is highly important to ensure the right sized wire in every electrical work so that the electricity flow can be uninterrupted between the circuits and the sub panel. In most cases, you need to use a #4 AWG copper wire or #2 aluminum wire to run a 100 amp sub panel.