Wire Size for Underground Feed of 200 Amp Service

Are you getting ready to install a 200-Amp service and need to know what size wire you are going to need?

In this guide, you will learn:

• What a typical 200-amp service wire size requires
• National Electrical Code (NEC) Rules for services
• Why voltage drop needs to be figured into sizing
• And more!

Before installing an electrical service, it is important to be sure that the correct gauge wire is used for the size of the panel.  As an electrician, I can't express how important it is to have the proper size wire and the proper grounding.  It is not only a matter of performance but also a matter of safety!

This guide is to be used just as a guideline for wire sizing.  A licensed electrician should be the one to size the panel due to the factors that needs to be considered. They also know all the national and local electrical codes that need to be followed and permits that need to be obtained.

200-Amp Service Wire Size According To The NEC

When installing a 200-amp panel, the National Electrical Code requires a minimum of a #2/0 AWG for copper wire. If you are using aluminum, or copper-clad wire no smaller than a #4/0 AWG must be installed.

These service wires will run from the electrical meter box to the main power panel that will supply power to the rest of the house. As a homeowner, you are responsible for having the meter box installed and the service entrance wires run into the main electrical panel.

SERVICE RATING (AMPS)	COPPER CONDUCTOR (AWG)	ALUMINUM OR COPPER-CLAD (AWG/KCMIL)
100	4	2
150	1	2/0
200	2/0	4/0
250	4/0	300

What Size Ground Wire for A 200-Amp Service?

A 200-amp service must have a #4 AWG copper wire or a #2 AWG aluminum wire running from the grounding electrode system to the main power panel.

There will be a green screw that needs to be installed called the main bonding jumper.  This bonds the panel to the neutral/ground bar. It is important to note that youDO NOT use a main bonding jumper if the panel being installed is a subpanel.

Copper Conductor	Aluminum Or Copper-Clad Aluminum	Copper Grounded Conductor	Aluminum Or Copper-Clad Grounded Conductor
2 or smaller	1/0 or smaller	8	6
1 or 1/0	2/0 or 3/0	6	4
2/0 or 3/0	4/0 or 250	4	2

***above table is in AWG/KCMIL

How Many Wires For A 200-Amp Panel?

For a standard home electrical panel there is a total of 3 wires installed from the meter base. Typically, a cable is used but it is acceptable to pull individual wires.

Two are the ungrounded or hot conductors, these are typically red or black in color. Each one carries 120 volts, providing the panel with the ability to power 240 volts. The third is the neutral wire and will terminate on the neutral/ground bar.

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What's The Difference Between Copper And Aluminum For 200-Amp Service?

The size of your conductors for a 200-amp panel depends on the material of the wire. The most common are copper, aluminum, and copper-clad aluminum. Here are the pros and cons of each type:

Copper Wire

Pros

• High Conductivity -Can be run longer distances with less voltage drop allowing for smaller gauge
• Flexible -thinner stands of copper allowing for easier bending
• Heat/Corrosion Resistant - doesn't expand and contrast in the heat making it more of a durable installation, it does oxidize but that doesn't affect the performance

Cons

• Higher Price -it is more expensive to install
• Heavier -it is more complex to install due to its weight

Aluminum Service Wire

Pros

• Easier Installation - lightweight and easily installed quickly, larger gauge but still lighter
• More Affordable -Lower cost than copper wire

Cons

• Corrosive - Requires antioxidant coating on any bare wiring, corrosion can create fire hazards
• Susceptible to Heat - any temperature change can cause the wire to expand and contrast creating loose connections which can lead to fire hazards
• Special Parts -any connectors, screws, lugs, terminals must be aluminum rated
• Longevity -may need to be replaced sooner than copper due to corrosion or damage

Copper-Clad Aluminum Wire

Pros

• Cost Savings - Cost less than copper but more than aluminum
• Light Weight - lighter than copper but just as durable
• Corrosion Resistant -Does not require antioxidant coating

Cons

• Durability - softer, more susceptible to damage
• Conductivity - lower conductivity than copper

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Other Things To Consider For 200-Amp Panel Wire Size Installation

#1. Type of Conduit for 200-Amp Conductors

Service entrance cables should be installed in a conduit to protect them from damage.

For underground service the minimum is a 1.5-inch schedule 40 or 80 PVC conduit.

A 200-amp panel using three 2/0 AWG, it is recommended to use a 2- or 2.5-inch conduit for easier pulling.

#2. Voltage Drop And Why Length Matters

Voltage drop can be easily explained as the voltage is less at the end of a run than it is at the start. As wires get longer, the resistance increases causing the voltage to drop. This is called impedance. To counter the dip in voltage the wire gauge size must be increased.

The NEC recommends a 3% voltage drop or less on branch circuits or feeder cables to ensure proper performance.

For example, if you start with 120 volts at the beginning of the run you shouldn't have less than 116.4 volts at the end.

The tables below list the AWG size at 100- and 200-amps vs the length of wire to maintain a 3% or less voltage drop.

A copper wire will be a smaller gauge than aluminum because aluminum is not as conductive or heat resistant.

It should be noted that temperature can affect voltage drop as well.

200A SERVICE WIRE SIZE	MAXIMUM DISTANCE
Copper 2/0 AWG	50 Feet
Copper 3/0 AWG	100 Feet
Copper 4/0 AWG	150 Feet
Aluminum 4/0 AWG	50 Feet
Aluminum 300 kcmil	100 Feet

#3. 1-Phase Versus 3-Phase

Homes are set up for single phase power.  Three phase power is something to consider if you are wiring a shop and have equipment that has a larger amp draw. The difference is three-phase power has 3 hot conductors instead of two.

Three phase power is more efficient than single phase power therefore requiring smaller wires for the same amperage.

Keep in mind that three phase power must be coordinated with the utility company.

Does 200-Amp Wire Size Require Grounding?

Every home requires a grounding electrode system. Simply put it is the grounding system that attaches the ground in the panel to a conducting object that is in direct contact with the earth.

The length that each one has to be in contact with the earth, is dependent on which style is used.

Ground Rod or Pipe Electrodes

Ground rods are the most common grounding electrode used in residential situations. Ground rods can come in a variety of materials; they can be stainless steel and copper, or zinc coated steel.  No matter what the material it is made of it must be no less than 5/8 inch in diameter.

A pipe electrode must have a galvanized outer surface or be metal coated to protect against corrosion. The pipe cannot be any smaller than a trade size of 3/4 inch.

When using either of these electrodes they must be in contact with the earth for no less than 8 feet.

Ground Ring

Ground rings are not typically used for residential purposes but are allowed. It is exactly what it sounds like, a ring of bare copper wire encircling the structure.  The wire must be no smaller than 2 AWG and be in direct contact with the earth for no less than 20 feet.  It also must be installed no less than 30 inches below the surface of the earth.

Metal Underground Water Pipe

Underground water pipe is allowed to be used as a grounding electrode providing it is in direct contact with the earth for a minimum of 10 feet.  If it is not electrically continuous you can place jumper wires on sections that may be insulated or have insulating joints to make it so.

Supplemental Electrodes

It may seem odd to have done all this grounding and still need to have more, but if one of the previously listed electrodes has a resistance to earth of 25 ohms or more, you must install a supplemental electrode.

If installing an additional ground rod, it must be within 6 feet of the original one.

No matter which electrode is used for supplemental purposes it must be bonded to the original electrode using no less than a 6 AWG copper wire or a 4 AWG aluminum wire.

Are Permits Needed For 200-Amp Service?

While the National Electrical Code sets the basis for all electrical codes, your local codes can go above and beyond what the NEC says.

Local ordinances can adopt and alter the NEC to the requirements of the area. A local electrician will know what these codes are and ensure your 200-amp service is sized and installed appropriately.

Before you begin any work, you will need to pull a permit for the work being done. Utility companies will not install the meter base until the electrical inspection has been passed.  After inspection has been passed, you will be able to obtain a Certificate of Occupation.  At that point power will be able to be connected to your house.

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What Is The Average Installation Cost For 200-Amp Service ?

The average cost to upgrade or install a 200-amp service is around $750 to $2,000.  Of course, there are many factors that play into this price.  The cost of wire is continuously fluctuating as well as the cost of labor in your area.

If you have to completely install a new panel, breakers, and wiring the cost can go up to an average of $4,500.

Frequently Asked Questions

What Size Copper Wire Do You Need For a 200-Amp Service?

For a 200A service wire, you will need to install a 2/0 AWG copper wire with a #4 AWG ground.

What Size Wire Do I Need For A 200-Amp Service 200 Feet Away?

To maintain less than a 3% voltage drop 500 kcmil wire should be ran for a 200A service wire. To make sure you get the wire sized properly have a licensed electrician do it.

How Many Wires Do I Need For A 200-Amp Service?

For a standard 120/240 volt residential 200-Amp panel, you need 3 wires. Two wires will be the hot conductors and one will be the neutral wire. A ground wire will be installed separately.

How Far Can 4/0 Wire Run?

A 4/0 wire should not be run any further than 250 feet to maintain less than a 3% voltage drop.

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Final Thoughts

When installing a 200-amp panel there are multiple factors to be considered from the wire material, the length of wire, to the temperature of the area it will be installed in.

A general rule of thumb is if you are installing a 200-amp panel you will need to use a 2/0 AWG copper wire or a 4/0 AWG aluminum or copper-clad wire.

If you are running the wire a short distance, it is your preference as to what type of wire you install.  If you have a longer run it is suggested to go with copper wire due to its conductivity and heat resistance helping to combat voltage drop.

Overall, it is recommended to have a professional electrician size and install your service.  They are familiar with how to size the wire in accordance with the local and national codes and the proper permits that will be required for the project.

I hope you enjoyed this Home Inspector Secrets guide!

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