What Size Wire for 200 Amp Service?

When it comes to electrical wiring, using the right size wire is crucial. The size of wire you use determines the amount of current it can safely handle. 

If you are looking to install a 200 amp service wire or breaker in your home, the minimum size of wire you will need is 4/0 awg copper wire, or 350 KCMIL if the wire length is over 100 feet.

Using the wrong size wire, say 2/0 copper or 4/0 gauge aluminum wire, may cause circuit overload, tripping breakers, and electrical hazards.

KCMIL or MCM is a gauge used to measure wires that are larger than 0000 or 4/0 awg wire.

Warning: Never try to install a 200 amp service wire or ground wire if you are not a qualified electrician

It is purely the work of an electrician who understands wire sizing, NEC code and electrical safety.

Keep on reading to learn more about the 200 amp wire size and uses.

Areas where you can use 200 amp wire size

A 200 amp wire is a heavy duty electrical wire used in areas that require high current flow. Below are some areas where you can use the 200 amp gauge wire.

Residential electrical service: A 200 A wire is used to connect the residential service panel to the main service lines. It can deliver enough power required to run large appliances and electronic devices.

Electric motor charging stations: As electric vehicles become popular, the demand for high power charging stations is increasing. 200 amp wire is used to supply the required current for quicker charging of vehicles.

Commercial and industrial electrical systems: Large commercial and industrial buildings often require more power than residential houses.

A 200 amp solid wire size is used to supply power to the machinery, lighting, and HVAC systems.

Solar panel system: Solar panels generate direct current that needs to be converted to alternate current before use.

A 200 amp wire is used to connect the panels to the inverter, which converts the DC to AC that can be used in the house.

Ground wire: A home that uses 200 amp breaker will also require the same ground wire for earthing.

Are Permits Needed For 200 Amp Service?

Yes, a permit is necessary before installing 200 amp service. Electrical work of this nature requires a permit. It is essential to consult with your local building department or relevant authority to determine the specific permit requirements for your location.

Getting a permit will ensure that the electrical work is done safely and in compliance with the applicable codes. It also allows for inspections to be conducted to verify that the installation meets the standards.

When planning to upgrade to a 200-amp service or any other significant electrical work, it is always recommended to contact a licensed electrician who is familiar with local regulations. He can guide you through the permit process and ensure that the installation is standard.

How to determine the right size wire for 200 amp service

In order to get the right wire size for your 200 amp electric service, there are some factors you must consider.

These include the NEC 83% rule, voltage drop rule, type of wire used and whether it is surface or underground wiring.

National electrical code (NEC 83%) rule

The NEC 83% rule is a guideline set by the National Electric Code (NEC) for determining the maximum load a circuit can handle.

According to 2017 NEC 310.15(B)(7), the maximum load a 200 amp circuit should carry must not exceed 83% of the circuit’s capacity. This is to ensure safety and to prevent overloading.

Note: This 83% rule only applies to single-phase services rated between 100 to 400 amps.

Therefore, 83% of 200 amp is 240.96 amp. You can get this by dividing 200 amp with 83% or 0.83.

If you check the wire gauge ampacity table, you will see there is no 240.96 amp there, so we use the next closest ampacity, which is 260 A.

The 260 amp circuit will require a 4/0 gauge for maximum performance. So the perfect size wire for 200 amp service is 4/0 awg.

Voltage drop rule

Voltage drop is the loss of voltage that occurs when the current flows through a conductor because of its resistance.

The voltage drop rule helps to account for voltage loss when running a long distance service wire.

Let’s say you are to install a 200 amp electrical service 100 feet away from the main panel. The law requires you to increase the amps by 20% on every 100 ft distance.

Here is the formula: Power (Watts) = Current (Amps) × Voltage (Volts)

200 amp wire 100 feet away = 260 A x 1.2 = 312 A. 

Now, let’s look for a wire with 312 A ampacity. If you check the wire size chart above, you see that the 350 KCMIL wire is perfect for 200 amp service 100 feet away. That’s because it has a 312A ampacity.

Type of wire used

Copper and aluminum are the most common wires used in electrical installation. The one you use determines your wire size.

Copper wires are better conductors of electricity, thou more expensive but can handle very high current.

On the other hand, aluminum wires are more prone to corrosion and require larger sizes to handle the same amperage. You should weigh their pros and cons before making your choice.

Watch this video to learn how to install a 200 amp circuit.


As you can see from this article, the correct wire size for 200 amp service is 4/0 awg. Avoid using the wrong size wire for the installation.

If you cannot do it yourself, call a licensed electrician. He will be in a better position to apply all NEC codes, permits and safety practices.

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About mariaelectricals

Hi, I am Emmanuel Nwankwo, a commercial electrician and the founder of mariaelectricals.com. I established this blog to share my decades of work experience in electrical installations and repairs.