Last Updated on October 22, 2023 by Kevin Chen
Image source Polar wire
For a 200A service, you will need a 2/0 AWG copper wire and 4/0 AWG aluminum wire. Keep in mind that the above two figures will depend on the length of the wire. That implies that 2/0 on copper wire will be for the distance of up to 150 feet. The same applies to the aluminum wire- 4/0 should be for up to 150 feet. Beyond 150 feet then you will have to get a bigger wire keeping in mind that there is a direct relationship between the distance are resistance. The longer the distance a wire covers, the higher the resistance.
But that’s not all. There is more that you should know about the perfect wire size for the 200A service. Keep on reading as we break down this information for you in the simplest way possible.
NEC 83% standard
How did we arrive at the 2/0 AG for copper and 4/0 AWG for aluminum wires? Well, it is all about following the NEC’s 83% rule for the wire sizes.
To sum up the rule, ampacity of the wire should not go below 83% of the main supply line. The 83% is considered the maximum safe load capacity of both the wire and the circuit breaker and is usually applied on the service lines that transmit between 100amps to 400 amps.
In our case, we are talking about 200 amps service. When we do the calculation, it will be 200× 83% which will give you 166A
From there, you can go to the American Wire Gauge Table and see where the 166A falls. From the table, it is illustrated that 2/0 will be able to support up to 200 amps hence making it an ideal choice for this service line.
Types of wires: Copper vs Aluminum
Copper and aluminum are the two main materials used as conductors for major electrical applications such as 200 Amps service. When comparing the two, copper is definitely a better conductor. This explains why it has a wide range of applications globally.
Copper has other desirable properties such as flexibility and strength that make it a better conductor than aluminum. However, it is more expensive than the aluminum wire.
In most cases, aluminum will be used only as an alternative. It is lighter and of course cheaper than the copper wire.
So, why the difference in sizes?
As we have already mentioned, you will use 2/0 AWG for copper wire and 4/0 for the aluminum wire if your service is rated 200 amp.
The main difference comes in terms of the conductivity. Copper has a better electrical conductivity rating than aluminum. This means that it has the capacity to carry more electric currents per cross-sectional area than the aluminum wire. At the end of it, copper, which will have a smaller diameter will carry the same load as the aluminum wire.
On the other hand, aluminum conductor has a lower density than copper wire. This implies that the aluminum wire with the same diameter as copper will have more resistance than copper. This is another reason why aluminum wire should be larger than the copper wire.
Thermal issue also comes in handy when it comes to the difference between copper and aluminum conductors. Aluminum has a higher coefficient of thermal expansion than copper. This implies that it is likely to expand more with a slight change of temperature than copper. This expansion can lead to loose connections in case of temperature difference.
All these reasons we have mentioned point out to the main reason why aluminum wire for the 200 amps service will always be larger than the copper wire.
Overview of the 200 amp service
Image source Skycraft supplies
We have already seen that you will need 2/0 AWG and 4/0 AWG wire sizes for the 200 amp service. But what does this service mean?
200 amp service refers to the current capacity of an electric service panel in a building. In this case, the maximum current capacity is 200 amperes.
Remember that the service panel is sometimes known as the main breaker panel and it is main distribution point of electricity.
200 amp service is quite common in residential and even commercial buildings. It is enough to power most electric appliances and devices whose power consumption range from medium to high.
In all the scenarios, the size of the service panel should always match that of the electrical load. And this applies to the wiring used. The size of the wire should match that of the panel.
Consider the voltage drop
While knowing the size of the wire is important, another key factor that you should consider is the voltage drop. This refers to the loss of electrical energy as the current flow through the wire The drop is usually due to the internal resistance that the wire offers to the flow of current.
Voltage drop is directly related to the distance covered. The longer the distance the more the voltage drop. This may end up affecting the performance of a device. To avert this, you need to consider the wire size that you are using on your 200 amp service.
NEC recommends that you should upgrade your wire for any circuit that has more than 5% voltage drop for the feeder circuit and 3% for the branch circuits. You should consider the distance between the source and the load when calculating the voltage drop. From there, you will be able to choose appropriate wire size.
So, what should my wire upgrade look like in relation to the voltage drop? The general formula is always upgrade with every extra 100 feet more. In our case, 2/0 is ideal for up to 150 feet. If you increase the length by 100 feet, then you will upgrade to a 3/0 wire and so on. The same applies to the aluminum wire.
Now that you know the perfect wire size for your 200 amps service, the next thing to consider is taking care of the rest of your circuit. Ensure that you install high quality electrionic components on the circuit.
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