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What Size Wire Do I Need for 400 Amps? (Quick Answers)

If you notice that your breakers and lights are dimming, there must be some issue with the electrical service. Additionally, you may also notice your outlets making a buzzing and cracking sound. 

If all the answers for the mentioned problems are positive, then it’s time you should upgrade your electrical system to 400 amps. It may be proven helpful for the issues you are facing. 

However, if you are wondering how much wire you need for 400 amps service, then you are at the right door. We are going to have a detailed discussion on this topic. So, to find all your answers stick with us till the end. 

What size wire do I need for 400 amps?

For 400 amps you will need 1000 kcmil. This is the amount of wire you’ll need when you use an aluminum wire. Additionally, if you are planning on using copper wire a 600 kcmil of wire is enough. Using the right amount of wire is necessary otherwise, it may lead to many risks.    

Usually in the old homes 100- amp electrical panels are used. The electrical service’s amperage is the amount of current  flowing through the wires. 

In the past, heavy-duty appliances weren’t used frequently. However, that has changed over the decades. Therefore, many homes have started using 200-amp services.      

400 amp service underground:

You need to use a 400 AWG wire for your 400 amp service that is installed underground. However, keep in mind that 400 amp services are only recommended for those homes which have a large amount of electrical needs. 

To run the appliances that are used regularly such as washer, water heaters etc. 

These regularly used  appliances can be run on a 200-amp panel without any issues. You do not need to upgrade or change your service unless you see visible signs. These signs include cracking switches, burning wires, breaker tripping etc.    

Therefore, you will need to use 400 AWG ground wire.  

400 amp 3 phase service:

For 400 amp 3 phase service, you will need a minimum of 600 kcmil-gauge wire. 

Before you upgrade to a 400 amp service, you will need permission from your electrical service provider. In some cases, you may also need to pay some upfront fee for the upgrade. 

However, in other cases it can be done for free. This depends on the area you live in. So, do your research before you plan any upgrade. 

Keep in mind that homes that have Saunas, hot tubs and other heavy-duty appliances need 400-amp services. These appliances require much more power than the average appliances.  

Aluminum wire for 400 amp service:

For 400 amp service you will need to use 270 amps of aluminum. Before you switch to 400 amps, check if your house already has 400 amps service. 

Usually, a home that has 400-amps service will show 400 amps. You can check the main breaker. It will show you a figure that ranges in between 50-400 amps.   

Copper wire for 400 amp service:

For 400 amp services you will need to use 355 copper amps. If you are in need to upgrade your electrical service then be sure to contact someone professional. Apart from that you may also need permissions from the local authorities. 

Additionally, it is important to use  the right amount of wires otherwise it may lead to various accidents.  

How much does 400 amp service cost?

A 400 amp service will cost around $2,000-$4,000. It’s better to keep in mind that the higher the amperage goes, the higher the cost will be. In case you are lucky, then your labor cost may be around $500-800. However, in other cases, the entire thing can round up to be a $3,000 cost. 

For the new electrical panels and wiring you’ll need to spend at least $600 to $2500. Additionally, replacing your old circuit breaker and fuse box will cost $2000 at most. 

The average cost that you’d need to spend on an electrician would be $2400. By now you must realize, the labor cost is the most expensive part when it comes to installing a 400-amp service.       

Do homes need 400 amp service?

Homes that have heavy-duty appliances, saunas or hot tubs need to have 400-amp electrical service. The homes that usually need more air conditioning and heating than average need to have a 400-amp service.  

However, the homes that have an average electricity usage can run with 200-amps without any issues. Any average 3-bedroom home would run using 200-amps. 

Additionally, before you choose to upgrade to 400-amps electrical service, make sure you need it. If you are not using equipment that requires a large amount of energy then you do not need to upgrade to 400-amps. 

Does wire size affect amperage?

Wire size does matter. When the diameter of the wire is larger it provides more area for the electrons through the circuit. Wire gauge is directly related to how many amps are going to pass through it. 

However, the distance that you are planning to cover can also have an impact on the gauge of the wire. Keep in mind that choosing the right sized wire is vital to install your 400-amps service properly. 

What happens if you use the wrong wire size?

Using the right sized wire for upgrading or installing a 400-amps electrical service. However, here are a few things that can happen if you use the wrong sized wire: 

Can cause unexpected fire Hazards: 

When you use a wrong sized wire it can lead to heat resistance. And later this can lead to causing a fire. 

Keep in mind that each cable is specifically made to accommodate  a certain amount of voltage. Therefore, if you use a wrong sized wire it will not be able to take the load of the electricity. 

As a result, the wires may end up melting due to heavy current flow. Other than that, short circuits can also occur. 

Can cause damage to appliances:      

Using an inappropriate sized wire can cause damage to your appliances. For example, an amplifier can get damaged when an inadequate amount of current flows through it. Therefore, if you are using a wrong sized wire, there’s a higher chance that your amplifier will not respond. 

It will not respond because it will not be receiving the right amount of voltage that it requires to perform.       

Final thoughts

For 400-amps you will need to use 1000 kcmil wire. However, you may also use 400-AWG wire. Before you plan on upgrading to 400-amps electrical service, make sure you need it. Additionally, be sure to choose the right wire or else it can lead to accidents and also damage your appliances.