What Size Wire For 200 Amp Service Underground?

Wondering what wire you need for 200 amp service? We'll help you with this and best practices for installation. We recommend using a licensed professional for this type of work. Take a look below at why you shouldn't tackle this project alone.

What Size Wire for 200 Amp Service Underground

If you are running an underground 200 amp service, then you may be wondering what size wire to use in your installation. We’re going to answer that question for you, however, keep in mind that you may need a permit and that a professional should do the installation.

Wiring 200 amp service must use either #2/0 for copper conductors or #4/0 aluminum or copper-clad wiring. Most electrical contractors use #4/0 aluminum or copper-clad wire. The wire used is determined by the length of wiring and voltage drop. Make sure to follow the code and get the right permits prior to installation. 

Electrical work can be a daunting task if you do not know all of the requirements, codes, and permit rules. You should start by finding out what codes and permits are needed in your area.

This information is provided as our informed opinion and does not constitute actual advice from a licensed professional.

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Wire Size for 200 Amp Service

An underground 200 amp service has a couple of different options, depending on what type of wire you plan on running. You can choose between copper conductors and aluminum conductors.

Copper is the most common conductor for wiring. It works so well because it has less resistivity than other metals. Copper also oxidates less and does not rust. It does produce a green patina, but in the case of copper, it helps protect the metal from further erosion.

For copper wiring with a 200 amp service, you will need to use #4 AWG copper wire. AWG stands for American wire gage, which is the standard for wire gage in the US.

The next option for a 200 amp service, is aluminum, or copper-clad aluminum. If you are planning on using aluminum wiring, keep in mind that it has lower conductivity than copper. To use aluminum with a 200 amp service, you will need to use #2 AWG aluminum wire. Click on the following link to read more about buying a house with aluminum wiring.

Using copper-clad aluminum can be a better choice, and will cost a little bit more.

Video: What Size Wire for Your Electrical Panel

Using Copper Conductors

We suggest using copper conductors if it fits into your budget. Copper is better than aluminum for many reasons. It has been the most widely used type of wire for 200 years and holds up well over time.

If your home has a large load capacity, then using copper will help make sure that everything that your house runs, will hold up to the 200 amp service you are installing. If you are worried about the copper wire turning black, don’t be. It is natural for copper wires to become discolored through the process of oxidation.

Using Aluminum or Copper-Clad Aluminum

Aluminum will work if you are on a budget. It is cheaper than copper, but does not conduct electricity as well, and could be less than ideal if your home has a large load capacity. For this reason, if you are using aluminum, we suggest copper-clad aluminum.

It helps the aluminum conduct better and keeps it from corroding as much. You will spend a little bit more, but you will be happy that you did.

Aluminum expands and contracts with heat, this can cause the wiring to loosen over time, and could eventually cause a fire hazard.

How Many Feet of Wire Are You Running?

You will also need to consider how many feet of wire you will be running. This can be a deciding factor, in whether or not you will use copper or aluminum wire.

While both wires are rated to be used with 200 amp service, copper can be used at longer lengths. This is because it conducts better and does not expand and contract like aluminum.

With long distances, aluminum can interfere with the flow of electricity. There are precautions you can take if you are going with aluminum, such as using copper-clad aluminum and using special copper fittings on the ends of the aluminum wire.

What is Voltage Drop?

When sizing wires for an underground cable is exactly the same as sizing for other household circuits. It is generally based on the total load, or electrical demand, of all the devices on the circuit. However, if the cable run is particularly long, as is the case with most underground runs, you may need to increase the size of the wire to compensate for voltage drop.

Voltage drop refers to a loss of voltage in the circuit from the natural resistance of the wires. A loss of voltage, or impedance, is indicated as a percentage of the total voltage at the power source. Extreme voltage drops means that appliances, and other devices connected to the circuit cannot operate as efficiently as they are supposed to.

For example, if you measure the voltage of a circuit at the breaker box, the standard reading should be 120 volts. Then, if you take another measurement of the circuit at the farthest device from the panel and obtain a reading of 114 volts, that particular circuit has a 5 percent voltage drop.

How Load Impacts Voltage Drop

As the load on a circuit increases, the voltage drop increases, and overload on a circuit will contribute to excessive voltage drop. Put simply, if you have too many loads on a circuit and surpass the standard 80 percent safe capacity, you will be adding superfluous voltage drop. To avoid this, maintain the total load on the circuit to 80 percent or less of the total capacity.

Sizing Conductors

It is recommended by the National Electrical Code (NEC) to use a maximum voltage drop of 3 percent for individual household circuits, or branch circuits. This number is also a good guide for sizing the conductors for an underground run.

Check the Codes

The codes can vary by state, or location, so always make sure that you check your local codes before having any electrical work done. The codes will let you know what AWG wire you should use, for any amount of amps.

While the wire sizes we have provided should be good enough to run your 200 amp service, there may be extra rules that apply to use them in your location.

If you are unsure of how to check the codes, or what they mean, make sure that you have a professional making the final decision. This can save you time and money, by avoiding mistakes early on.

Do You Need a Permit?

You may need a permit to install a 200 amp service. The last thing you want to do is get your operation shut down for not using the correct permits. Most large electrical operations, such as a 200 amp service, require a permit.

You will need a licensed professional to pull your permit. We suggest always using a professional when doing something of this magnitude. Electric work can be dangerous, even if you know a little bit about it. An underground 200 amp service has a lot of power, parts, and work that must be done properly.

Wire Costs for a 200 Amp Service

The costs of installing a 200 amp service is not cheap. You will be spending anywhere from $1,500 to $3,000 for a 2,600 square foot home. The cost will depend on the type of wire you use, whether it be copper or aluminum.

We suggest using copper or copper-clad aluminum if your house has a large load capacity. Paying more for copper wire will help to ensure that you will have no problems in your operation. If the aluminum wire ends up not being able to push the electricity correctly, it will be a costly job of replacing it.

Tips for Installing a 200 Amp Service Underground

Here are a few tips that will help determine what is needed for installing a 200 amp service. These are best practices that you should try to follow.

  • Use a licensed professional. Do not cut corners when it comes to electrical work of this size, always use a professional. Performing electrical work is incredibly dangerous and should only be done by a certified expert.
  • You will need an inspector for a 200 amp service. Since this is a big operation, you will have to have a permit and an inspector.
  • Never take chances with safety. Do not perform any of this work if you are not a licensed professional, this guide is meant to teach you only what is involved.
  • Use special fixtures with aluminum. If you are using aluminum wire, consider using special copper fixtures that are pigtailed onto the ends of the aluminum.

As always, working with electricity requires special caution. It is crucial that you NEVER attempt any sort of electrical work without the necessary experience.

Follow the above best practices, and you will be well underway to getting your 200 amp service, with the correct wiring.

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Related Questions

What is involved in upgrading to a 200 amp service?

Upgrading to a 200 amp service will set you back $2,000 to $3,000. You will need a licensed professional, involvement from the utility company, and a local inspector. This process will also require that you apply for and obtain a permit.

Does underground wire need to be in conduit?

Only direct burial cable can be used underground without conduit. In most cases, you will use a conduit in your underground electric operation. Even with direct burial cable, you will need to use a conduit where it comes up out of the ground and into the box.

Chad Kilpatrick

I'm a writer that is passionate about home improvements, remodeling, and renovating. I enjoy learning new skills and techniques and sharing them with others.

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