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What Is 400 Amp Service and Do You Need It [Explained]

It’s a very pathetic feeling when you see your light is dimming. Or your electronic devices aren’t working properly. Or your circuit gets warmer and you are worried about any fire hazard. This is when you need to upgrade your electric services to 400 amp. 

What exactly is 400 amp service?

400 amp service refers to the capacity of your home electric service. The current that flows through the whole electric circuit is mostly measured in amps. Most old households have 100 amps electrical panels. But the new and large ones need the 400 amps service. And there are many specifications from which you can choose. 

You might be still pretty dizzy about these matters, and pretty much confused also. That’s why I have mentioned the important parts regarding this very issue. 

That’s why relax and let’s start! 

400 Amp Service: Specifications 

The term 400 amp service means the capacity of your home electric service. The capacity is actually measured by the amp. This also means that the current flows through the wire. 

So, in simple terms, the whole 400 amperage current flows through the wire and its maintenance is the 400 amp service.

Making an upgrade on your electrical panel service may seem like a big deal. That’s why it might not be an idea that comes to your mind in the first place. 

But you might be facing problems like dimming light repeatedly. Moreover, breaker tripping, extension cords making weird noises can be issues too.

In these cases, you surely need to upgrade your electrical service. Or you should give it a thought. 

To upgrade your electrical panel 400 amp service can be the best option nowadays. But you first need to know the detailed specifications of 400 amp. 

Here are some general specifications of 400 amp that you should know- 

Current 400-500 A 
Rated Input Current27.4 A. 
Input Voltage 41r Voltage AC. 
Input Power 7.3 KVA 
Duty Cycle 75% 
No Load Voltage75 Voltage ,DC 
Frequency 50/60 
Power Factor 0.93 
Efficiency80-85 % 

These are the most common specifications of 400 amp service. You can choose from various companies or various products. There are several products in the market. 

You might get confused choosing one. That’s why I have gathered the most recommended products on the market- 

Cooper B-Line 324 N, 400ACheck Current Price
Siemens WEP4411 400ACheck Current Price

These 400 amp service or welding machines are top-notch in the market.

Why Do You Need 400 Amp Service?

In the past, we didn’t need to calculate our electrical service. That’s why most of the old homes have a 100 amp service. 

Plus nowadays most of the common homes have 200 amp service. Because they don’t need to use that many electrical appliances. 

But with time, we are now using a lot of electrical appliances. We use appliances like heating and cooling appliances, huge pool appliances and so on. 

These appliances give huge pressure on the electrical outlet and also the whole maintenance system. 

To avoid these and any hazards in the household, upgrade your electrical service to 400 amp. But before upgrading your home electrical service you need to decide if you need an upgrade or not. 

For that, you need to calculate your electrical needs, as well as check for symptoms.

How to Determine If You Need 400 Amp Service?

A 100 amp service is generally good for powering up a small or moderated household. It’s even good for a single bachelor living house. Plus it can easily power up some small range water heaters or clothes dryers. 

A 200 amp service will handle the same load as a 100 amp service. But you can easily attach some more devices. For example, you can add devices like heating or cooling equipment for small or medium-sized houses. 

A 400 amp service is recommended for a larger household. If you have a larger house with pools and other electrical appliances, choose 400 amp service. 

This service is mainly recommended for an electric heat load of over 20,000 watts. But this much info might not be enough to know if the upgrade is needed. 

That’s why try the below two methods as well-

Calculate Your Electrical Needs 

To calculate your electrical need you need to check some specific things. Here are some steps you need to perform- 

  • Determine the wattage capacity of all lights and general electrical appliances. And add them together. 
  • Add all the wattage ratings of all outlets together. 
  • Determine all the larger appliance wattage ratings now. 
  • Add the whole wattage rating together and convert the whole ratting to amp. 
  •  Be sure to deduct the 20% buffer. Because you can’t think of 100% accuracy to your electrical panel service. 

It’s best if you hire an electrician to calculate your household electricity service and capacity. 

Look for Some Symptoms 

You need to test your light switch after you see some obvious symptoms. Just like that, you don’t need to upgrade your electrical service unless you see some symptoms. 

Sometimes you may not even notice the symptoms easily. That’s why I have pointed out the obvious signs-

  • The breakers of your electrical circuit are tripping. 
  • The lights get dim, especially when you plug in more devices or turn on more lights at a time. 
  • You can also hear a buzzing sound at the outlet of the switch. 
  • Ware or outlet or other switch can get warm, specially when adding more devices at a time. 
  • You will even notice some burning smell of plastic coming from the wire or outlet 
  • You might notice appliances or other devices that work strangely or aren’t fully powered. 

Seeing these symptoms in your home appliances or your electrical outlet or circuit? If so, you should consider upgrading your electrical service to a 400 amp service.

You now know why you should upgrade your home electric service to 400 amp. But read along to know how you can upgrade it.

How to Upgrade to 400 Amp?

If you calculated your home electrical usages, you have done a complicated thing. But upgrading to 400 amp is more complicated. 

In most cases, there can be one easy way to upgrade the house amp service. That’s by submitting a request to the local electrical service provider. Once they get the request, they will upgrade your service.

Other than this way, the upgrade is actually free. Because you can hire a third party. This third party is basically a contractor with experience, and skill for upgrading the electrical service. 

After hiring the contractor, he will inspect and evaluate your house electrical service. This way he can identify what tools are needed for the upgrade. 

The contractor will also fix the cost that you’ve to pay for the upgrade. If you’re okay with it, your contractor will begin his work. 

But before that, the contractor needs the approval of your local electrical service provider. This is mainly for the panel location. 

It’s better to hire a contractor than to do this job yourself. Because this way you’ll be confident that your electrical service upgrade followed all the local codes. 

You can also get some breakers as they might be needed. Here are some recommendations for it as well:

Schneider Electric, QO120, Circuit BreakerCheck Latest Price
Homeline Single-Pole Circuit BreakerCheck Latest Price

What Is the Cost of Upgrading to 400 Amp?

The average cost of upgrading to 400 amp is $1500-4000. You might think it’s way too high. But you should think of the safety of your house. 

The total cost includes the panel at around $500. This is along with the other cost and 8 to 10 hours of labour. 

The total installation cost is mainly based on setup. In some cases you might install two 200 amp panels. One remains as the main panel. And the other one remains as the substitute panel for the home. 

In this case the panel cost will be reduced. But on the other hand, the labour cost will increase. 

If you set up a 400 amp, the labour cost will reduce. But the main panel cost will be much higher than two 200 amp panels. 

As a result, you can see the cost varies. Just how the cost for installing an interlock kit for your generator also varies. That’s why the choice is yours; which way you want to upgrade to 400 amp service!


Question: What size of wire is needed for 400 amp service?

Answer:  400 amp wire service needs a wire of 1000 kcmil. This is in case the wire is made with aluminium. But in the case of copper wire, you need 600 kcmil.

Question: How to tell if I have 400 amp service? 

Answer: You’ll see the electrical service’s amperage rating through your main circuit breaker. You must see the panel box’s main breaker switch. This way you’ll come across a figure where there’s a range that goes from 50 to 400 amps. If your house’s electrical service is upgraded to 400 amp, you’ll see the figure is at 400.

Question: How many amps do a 3-4 bedroom house need?

Answer:  Nowadays there are modern 3-4 bedrooms in our houses. This type of house needs around 100 amps to function properly.


That’s all from me. Hope now you know all about the 400 amp service and its specifications. 

You can now hopefully avoid the overwhelming fire hazard. Also, ensure the safety of the house by upgrading to 400 amp service. 

Best of luck with your new 400 amp electric service!