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What Size Wire For 200 Amp Service Underground?

Installing a 200 amp service water ensures your home has enough amperage and voltage to power all of your home’s devices. 

But many places require you to get a permit before installing a service wire. And because of the risks of electrical shocks and fires, many people have to use a professional electrician to install your 200 amp service wire. It’s crucial to use the proper size of wire for your service wire. 

Keep reading to learn more about the proper size wire for your 200 amp service. We’ll also explain amperage and what amp you’ll need for your home.

What Is Amperage?

There are two types of measurements to define the strength of an electrical current-voltage and amperage. It’s important to understand these two measurements if you’re working with electricity. Mishandling electricity can lead to dangers such as electrical shock. 

Amperage is the measurement of the volume of electrons in an electrical current flow. Amps (short for amperage) are more dangerous than voltage, which measures the pressure that makes the electrons flow.

If this sounds confusing, think of it like this. If you have a flowing river, amperage will define how much water is in the river. And voltage would describe the river’s steepness – pitch. 

When a river has a low amperage and a high voltage, it would be small and flowing almost vertically, like a waterfall with a slight trickle. If a person comes into contact with this type of electrical current, it will give you a jolt, but it wouldn’t be harmful.

Now picture a very deep river with a lot of water. Although the current is moving slowly, you can still get pulled underwater and drown. So, if you come into contact with an electrical current with very high amps but very low voltage, you can be at risk of serious injury due to electrical shock. 

The chart shows the dangers of different amps by electrical shock.

  • 1 to 5 mA: Slight feeling of electrical shock that’s not painful
  • 6 to 30 mA: strong shock that’s painful and causes loss of muscle control
  • 50 to 150 mA: severe painful shock that can cause severe muscle reactions that can lead to respiratory arrest and potential death
  • 1,000 mA to 4,300 mA: stops the heart, causes nerve damage and high risk of death
  • 10,000 mA (10 amps): severe burns, cardiac arrest, and death

As you can see, placing a 200 amp service underground must be done with extreme caution to prevent the risk of serious injuries or death. 

Average Amp Range For Residences

The circuits in your household outlets supply 15 to 20 amps (15,000 to 20,000 mA). The more amps you have, the more power you have to use multiple devices simultaneously.

Standard homes have 100 amps. But for larger homes or homes with central electrical heating or air conditioning, you’ll need 150 to 200 amps.

Older homes may have the capacity of 80 amps, which is rarely enough to power a bunch of devices and a central heating and air conditioning system. 

What Size Wire For 200 Amp Service

Installing a 200 amp service requires the use of the correct wire gauge. And if you’re doing the installation yourself, you will have to get a permit first. Some locations may require you to hire a professional electrician to obtain the permit for you. Again, it’s best to check with your local building department for information.

For a 200 amp electrical service, the gauge you’ll need will depend on the type of wire used, the length of wiring, and the voltage drop. 

Copper wires use a #2/0 AWG (American Wire Gauge) copper wire. In contrast, 3″ conduit covering copper-clad or aluminum wires require #4/0 AWG. This chart shows standard wire sizes by amp and wire type.

Service (Amps)Copper (AWG)Aluminum/Copper-Clad Aluminum
10042
11031
12521/0
15012/0
1751/03/0
2002/04/0
2253/0250
2504/0300
300250350
350350500
400400600

When to Use Copper Wiring

Copper wiring is more popular because the material is more resistant to heat, and it doesn’t rust or oxidize if it gets wet. Although copper wires can be thinner, it’s also more expensive.

The number of feet of wire you’ll be running can also affect whether you’ll want to use copper, aluminum, or copper-clad aluminum. Copper is the better choice for long lengths due to better conductivity and lesser contraction.

When to Use Aluminum

Aluminum is another popular choice because of its affordability, flexibility, and it’s more lightweight. However, this material has a lower heat resistance and can rust when it’s wet, so it needs an antioxidant coating on the connection terminals.

Aluminum wires require a larger size gauge since it’s less conductive than copper. In addition, aluminum-clad in copper does not need the same antioxidant coating on the terminal ends.

Beware the Voltage Drop

And when you have to run the cable underground over long distances, you can experience voltage drop – when the circuit experiences a voltage loss. 

Voltage drop – impedance – listed as a % of the voltage total on the power source can cause your appliances and the other things powered by circuits to have minimal power. The standard reading for circuits in the breaker box should be 120. 

If a circuit reads less than 120, that breaker is experiencing a voltage drop. When you put too much load on a circuit, and it exceeds 80% voltage, you can experience a superfluous voltage drop. The NEC (National Electrical Code) recommends a maximum drop of 3% and keeping the total load to less than 80%.

Costs for 200 Amp Service

Pricing for installing a 200 amp service placed underground will vary by factors like location, material costs, and permits. How much work is necessary will also play a role in the prices.  

Most installations of 200 amp service require running the service wire, a meter base, conduit, and the electric panel to control the 200 amp service.

You can expect to pay between $1,600 and $6,100 for the total costs of installing the entire 200 amp system. The average median is around $3,700, based on the following:

  • Amp panel – $500 to $4,000 ($2,000 median)
  • Amp meter base – $100 to $650 ($450 median)
  • Service wire – $1,000 to $1,500 ($1,250 median)

How To Determine Your Electrical Amp Needs

To determine your needs regarding how much amperage your system will need, follow these steps. You may want to write these numbers down to manage your calculations. 

  1. Multiply the square footage of your house by 3 watts (how much power your lights and receptacles use)
  2. Add an additional 1,500 watts per small kitchen appliance or laundry room circuit.
  3. Add wattages for additional appliances using individual circuits (dryers, water heaters, range, window air conditioners).
  4. Combine all three totals from steps 1 through 3 with the first 10,000 watts at 100% and 40% for all remaining watts.
  5. Add in the wattage of the central A/C or the heating unit (whichever is higher).
  6. Divide the total by 230 to get your home’s amperage needs.

To demonstrate this math, let’s show a house with a square footage of 3,000 feet with a central heating and air conditioning unit.

  1. 3,000 x 3 = 9,000
  2. 4 x 1,500 (three small appliances in kitchen plus one circuit for laundry room) = 6,000
  3. Dryer – 5,500 + water heater – 5,000 + dishwasher – 1,200 = 11,700. Then add 11,700 to the first two numbers (9,000 + 6,000) = 26,700.
  4. Allot 10,000 of the 26,700 goes at 100% = 10,000. The other 16,700 goes at 40% = 6680 watts. 10,000 + 6,680 = 16,680
  5. Add 4,000 for the central air wattage = 16,680 + 4,000 = 20,680.
  6. Divide 20,680 by 230 = 89.91 amps. Therefore a 100-amp service would suffice. 

Tips for Installation of 200 Amp Service

Installing a 200 amp service should not be a DIY attempt if you have little to no experience with electrical work. Improperly installing electrical wires can lead to dangers like electrical shocks, electrical fire hazards, and short circuits. 

Here are some helpful 200 amp service installation tips. 

  • When choosing an electrician to install your service, it’s crucial to do your research to ensure the person you choose is licensed, experienced, and certified.
  • You will need an inspector to check your service installation and permits before you can begin. In some cases, your contractor may have to obtain these permits for you.
  • When using aluminum wires, it’s better to pigtail copper fixtures to the ends of the aluminum pieces. 
  • And you should never work on electricity without turning off all power using the breaker box. Be sure to check the wiring for power before beginning any work. 

Conclusion

Choosing the right size wire for an underground 200 amp service is crucial for getting the proper power to the circuits to run all of the stuff in your house without overloading the circuits. Aluminum and copper-clad aluminum should be #4/0 AWG, while copper wire should be #2/0.