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Right Wire Size For 100 Amp Service 150 Feet Distance

Wires come in different shapes and sizes. According to your needs and the situation, the size varies. It might create a huge mess if you can’t choose the right wire for your work. However, you don’t need to worry, we got you covered.

What is the right wire size for 100 Amp service 150 feet distance?

You should get 2/0 AWG Copper wire or 4/0 AWG Aluminum wire for single-phase circuits. And, 1/0 AWG Copper wire or 3/0 AWG Aluminum wire if you have three-phase circuits. For these wires, the average voltage drop should be 3%. But it varies according to source voltage.

You asked and we delivered. However, there’s much more to it. Sit tight as we guide you through the details.

Calculating Wire Size For 100 Amp Service 150 Feet – Factors To Consider

Choosing the right wire size for your amp can be a huge hassle. Similar to picking 12-2 wiring for lights. Especially, if you don’t have adequate knowledge about electrical calculations. 

This is why you need to know some key factors before choosing a wire-

For example, the right type of conductor, voltage for your source, minimum voltage drop, the installation method of your circuit, number of phases, and so on.

Let’s briefly discuss these topics, shall we?

Type of Conductor

Now in order to choose the right wire gauge size, you need to know about conductor type. If you have some knowledge about conductors, you know that not every conductor has the same conductivity. However, two of the most popular and practical ones are copper and aluminum. 

Copper has a higher conductivity than aluminum. But it also costs more. Aluminum is very lightweight and easier to work with as it’s flexible. Both have their own characteristics, but you need to choose the one that fits your needs.

If you want to pursue an expansion of 150 feet for your 100 amp service-

We recommend you to get 2/0 AWG Copper wire or, 4/0 AWG Aluminum wire for single-phase. For a three-phase power source, 1/0 AWG Copper wire or, 3/0 AWG Aluminum wire can be used. 

To make your a little easier for you, here are our top picks for these wire sizes:

Spartan Power 2/0 AWG 20 Foot
4/0-4/0-2/0 Aluminum SEU Cable 600V Service Entrance Wire (50FT)
1/0 Gauge 1/0 AWG 10 Feet Black + 10 Feet Red Welding Battery Pure Copper

These wires should meet your needs if you want to extend your line to 150 feet.

Source Voltage

If you’re expanding your electric circuit, keep the source voltage in mind. Source voltage for households and industries may differ from place to place.

We refer to 120V as the standard source voltage in the US and Canada. However, industries might have a different source voltage.

Number of Phases

You may get confused hearing the word ‘phases’ associated with electricity. But it’s really a very simple term to understand. The number of phases in electricity refers to the distribution of load.

Usually, you’ll see two types of phases: single-phase and three-phase. For a single-phase circuit, you’ll require three wires. Whereas, for a three-phase circuit, you’ll need four. One of these should be a ground wire.

To identify what phase you’re using, take a look at the number of wires. 

Single-phase is usually seen in households and three-phase in industries. A three-phase circuit can accommodate higher loads better.

Voltage Drop

This might be somewhat of a geeky thing for you to understand. However, it’s an essential piece of information that you should know. 

When connecting a place at distance to the source via conductors, there’ll be some resistance in the electric path. That would cause the source voltage to drop. Even when you’re extending wiring with a junction box.

As the wire gets longer, the source voltage drops by some margin.

Usually, a voltage drop from 1 to 5 percent is alright (3% is calculated as optimal). However, you should ensure that the voltage drop doesn’t exceed 5% by any means. 

To measure the voltage drop, you could use a voltmeter. For such long wires, it’s better to get a professional to do this for you.

In that case, choose the wire wisely. If the wire diameter isn’t capable enough to carry the load, the voltage drop would be high. 

Installation Method

Sometimes the wire size may vary depending on the installation method you’re using. This can have some impact on the resistance that your circuit may encounter.

Typically you will find some common installation methods. The installations can be in a raceway (conduit or tray), buried in the earth, in a cable, or even in the open air.

The methods do depend on what wire you’re using. Contact a professional regarding how you should install your wiring. Otherwise, excessive overheating or other electrical accidents could occur.

What If You Choose Oversized Wires?

Well, if you’ve planned for future expansions, you may use oversized wires. This means the wire’s diameter is greater than you need.  

This won’t become a dealbreaker in terms of the current expansion plan. Only, if you maintained the rest of the things perfectly.

You shouldn’t see any significant changes in the performance of your circuit. Whereas, the only benefit you may encounter is a reduction in voltage drop. Although, anything below 5% is fine in the first place.

What If You Choose Undersized Wires?

If you use wires that are smaller than required, you may end up with bad news. Burning all of your devices, mainline, shed, and even your house or industry as well. Even one damaged outlet can ruin the others.

So, how does this work? When you choose smaller wires, you’re exposing the wires to greater resistance. This can result in excessive heat. 

This heat can melt the wire insulation pretty easily. You might end up burning the whole place down to ashes. Be careful while choosing the right wire size for your expansion.


Question: Is aluminum wire safer than copper?
Answer: Both copper and aluminum wires are safe to use. However, according to the U.S. Consumer Product Safety Commission (CPSC) reports, homes with aluminum wiring are more likely to have fire hazard conditions than those with copper wiring.

That does not mean that aluminum wires aren’t safe or should be avoided.

Question: Is maintaining less than 5% voltage drop mandatory?
Answer: Voltage drop is basically a loss of the voltage coming from the main 100 amp service panel. The higher the voltage drop percentage, the more inefficient the whole path will be.

For good and consistent performance, it’s recommended you keep the voltage drop below 5%.

Question: Single-phase vs three-phase. Which is better?
Answer: Single-phase circuits are seen in households and three-phase circuits in industries. However, you may use a three-phase circuit at home too.

It actually boils down to how many devices you’ll be putting through these circuits. If you want something that can handle higher loads, go for a three-phase circuit. Otherwise, single-phase circuits should be fine.


With this, we have reached the end. We hope that this article has helped you with new information and answered your question, “what is the right wire size for 100 Amp service 150 feet distance?”

If you want a hands-on understanding, try contacting a professional regarding any help.

Best of luck with your future endeavors!