What size circuit breaker do I need for my generator? (Explained) – HomeApricot (2023)

The size of the circuit breaker is not universal. Different electrical instruments and machines require different sizes of circuit breakers. However, the most common switch sizes are 15, 20, 30, 40, and 50.

However, you will find circuit breakers up to 6000 amps. But the question is what size breaker do you need for your generator. We have researched this topic and found several answers. It mainly depends on the capacity of the generator, but most standard sizes will satisfy the needs.

We will look at different wattages and suggest which breaker size is suitable for which wattage. Also, there is a shortcut to determine the size of the switch.

In short, it will be a one part overview where you will find everything about breaker sizing and generators. In fact, you can find the perfect size breaker for your generator.

What size breaker do I need for my generator?

You will need a 40-50 amp breaker for your generator if it comes standard size. Generators have different power capacities. Let's say you have a 2500 watt generator; In this case, a 30 amp breaker would be an excellent solution. Varies from device to device and depends on performance.

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What size circuit breaker do I need for my generator? (Explained) – HomeApricot (1)
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3500 watts:

If your generator is rated at 3500 watts, you will need a 30 amp 2 pole breaker. A 30A breaker can support a generator with more than 3500 watts.

This is why you should go for a 30A circuit breaker for your 3500 watt generator. No need to use a larger shredder. In this regard, also try to avoid size 20 or 25 switches.

5000 watts:

A 5000 watt generator requires a 35 amp breaker. This is a standard and safe size for this type of generator. You should avoid the advice if someone tells you to use a 30 amp breaker for 4500 to 5000 watts of power.

35 AMP is just the right size for your 5000 watt generator. So make your choice wisely and use the recommended breaker size.

5500 watts:

If you have a 5500 watt generator, you can choose a 35 amp breaker or a 40 amp breaker. However, you cannot use a 30A breaker. it will not serve its purpose.

However, for a 5500 watt power generator, a 35 amp breaker will suffice.

7500 watts:

The 40 amp 2 pole breaker is the perfect match for 7500 watts. That means if you have a 7500 watt generator you should use a 40 amp circuit.

8000 watts:

If you decide to use a standard size breaker like an 8000 watt generator, you should use a 45 amp size breaker. However, it is also possible to run generators up to 8000 watts with a 30 AMP breaker.

If you want to live safely, you should go for a 45 amp breaker.

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9000 watts:

If you buy a 9000 watt generator you should use a 50 amp breaker. It really is a perfect size. If you choose a 45 or 30 amp breaker, you won't be able to run a massive generator.

That's why you need a 50 amp breaker for your 9000 watt generator.

9500 watts:

A 50 amp breaker is the best option to run a 9500 watt generator. No need to use a larger shredder. You can easily run a 9500 watt generator with a 50 amp breaker. Therefore, it is the standard switch size.

10000 watts:

A 10,000 watt generator has to deliver enormous power. So you can't use a 30 or 45A breaker to operate it. That is why you need a 50 amp breaker for your 10000 watt generator.

12000 watts:

If your generator is running at 12000 watts and running on 240 volts, you should go for a 50 amp breaker. It's the right size breaker you can safely use with your generator.

13000 watts:

If you are purchasing a 13000 watt generator, it may be recommended that you purchase a 50 amp breaker. The main reason is high efficiency. And we know that a 50A breaker can easily handle up to 15000 watts of power.

That's why you need a 50 amp breaker.

What size circuit breaker for portable generators?

A 30A circuit breaker is the best choice for portable generators.. Portable generators are usually powered by standard power. It's not like a massive powerhouse. Therefore, for portable generators, you can use a 30-amp breaker.

As we have described, a 30A breaker can accommodate a generator of up to 8000 watts. If you have a 3500 watt portable generator, you can still use the 30 amp breaker. You don't have to go for the bigger switches.

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On the other hand, if your portable generator is only 500 or 1000 watts, you can use a 15 amp breaker. That being said, if you have a larger portable generator, go for a large circuit breaker. Conversely, if you have a small portable generator, you should use a 10-15 amp breaker.

What is the generator switch? Do the generators have circuit breakers?

The generator circuit breaker is a safety device that maintains proper current flow and controls voltage.. Connect the generator to the network or power source; The generator switch disconnects the mains if necessary.

It is mainly used for safety purposes and to reduce short circuit accidents. For this reasonGenerators have circuit breakers. Significantly, the generator is a power station.

Works with electricity. Sometimes you can get the high voltage that it can't stand; the circuit breaker then disconnects the generator from the grid and reduces the risk of short circuits.

How is a breaker sized for a generator?

To size a breaker for a generator, you can follow these steps.

Read the user manual:

Read the entire owner's manual that came with your generator. Try to know the exact KW and the lag factor. This is your first step in sizing a breaker for a generator..

Get the rated current:

Now you will get the exact rated current and power. You must divide the rated current by the power factor. You can get the rated current from the generator specifications. You need to know the current rating to determine the size of the switch.

Right Switch Size:

Now you know the correct size of the switch. Let's see that the nominal current is 50 AMP and the power factor is 0.8. In this case, the perfect switch size would be 59/0.8 ​​equals 62.5. That means you can use a 65 amp breaker.

These are the three simple steps to sizing a breaker for a generator. You can follow these steps and ideally get the correct size for your switch.

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How to install a switch for a generator?

If you are having trouble installing a circuit breaker on your generator, you can follow our tips and make it easier. There will be no more confusion and fighting.

Open the control panel:

First the panel opens. You can use a screwdriver and open all the screws first. But the fact is that you need to turn off the power, and then open the screws.

Look for the change option:

After opening the generator, you will see a part where you need to place the switch. It looks like a toggle option, but it should be empty.

Some generators are equipped with appropriate information signs to help you find the correct location.

Place in the desired position:

Now take your new switch and place it in the desired position. You can follow the instruction manual of the circuit breaker. Then you need to connect the wires.

There may be two different colors of wires. One can be red and the other is black. Connect them to the generator leads.

Connect the wires:

If you connect the cables correctly, you're done. It's time to close the opening window. Make sure you position the opener perfectly.

Restart the generator:

It's time to restart the generator. After that, your generator and circuit breaker are ready to go. You can run the generator and enjoy the service.

Here are the easy steps to install the circuit breaker on your generator. Nothing is difficult or complicated. If you still find it difficult, you can get help from a generator technician.

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It would be better to go to a local electronics store and ask the buyer to install the breaker. However, when you buy a new generator, in most cases the manufacturer will offer you a free service.

If you are an expert and know how to install a switch, you can follow these steps.

final thoughts

The perfect size of the circuit breaker depends on the current rating of the generator. But 30 amps might be the best size you need for your generator. However, you can easily calculate the size of the breaker by dividing the current rating by the power factor. You can follow our steps and calculate the size.


What size breaker do I need for my generator? ›

A circuit breaker on the generator protects the outlet, generator cord, inlet box, inlet box wiring, and the transfer switch from an overload. On most generators, the outlet is a 30-Amp or 50 Amp 120/240-Volt outlet and connects to a 30-amp or 50-amp 120/240-volt inlet box receptacle.

How do I choose a circuit breaker for my generator? ›

There are a few different criteria to consider when selecting a circuit breaker including voltage, frequency, interrupting capacity, continuous current rating, unusual operating conditions and product testing.

What size breaker do I need for a 7500 watt generator? ›

Watts divided by Volts equal Amps. Therefore, 7500/240 = 31.25amps on each 120 volt hot leg. We protect these circuits with 30 amp breakers.

What size breaker do I need for a 10000 watt generator? ›

10,000 Watts divided by 240 Volts equals 41.6 Amps. This unit requires a 50 Amp breaker.

How many amps are needed for a home generator? ›

The size of the generator is based on the type of appliances, equipment, pumps, air-conditioners and other electrical devices requiring power. Your service panel is normally rated at 200 amps @ 240 volts and the average home uses approximately 140 to 160 amps of 240 volts power to operate everything at the same time.

What size generator do I need to run my house during a power outage? ›

Most homeowners, however, will use a generator somewhere between 3,000 and 6,500 watts. You might also consider how prone your home is to power outages. If you live in an area extra susceptible to power loss, you should be more conservative with your estimate.

Does it matter if you use a 15 or 20 amp breaker? ›

You should never just upgrade from a 15-amp breaker to a 20-amp one just because the current one is tripping. Otherwise, you may burn your house down via electrical fire. To help you understand why this is so dangerous, you need to know what the circuit breaker is for.

Can you wire a generator directly to breaker panel? ›

Through Breaker Box: You can connect the generator with the breaker box. Use a separate breaker with a wire to connect the generator. When needed, the main breaker will cut off the power supply to the generator. To the Main Electrical Panel: You can also wire the generator to the main electric panel.

What size breaker do I need for a 5500 watt generator? ›

So, 5500 watts / 220 volts X 0.80 = 20 amps. If you have a 30-amp breaker, you should have plenty of amps to handle the element, associated electronics (which typically only draw a few hundred milliamps), and probably a couple March or Chugger pumps, too.

How many amps can a 12000 watt generator run? ›

Our powerful 12,000-watt generator provides up to 9 hours of run time on a full tank of gasoline.
Gasoline Starting Watts15000W
Gasoline Starting Amps at 120V125A
Gasoline Starting Amps at 240V62.5A
Gasoline Running Amps at 120V100A
35 more rows

Can I plug my 30-amp generator into a 50 amp? ›

Fortunately, adapters make it easy to hook your 30-amp cord to a 50-amp outlet (or vice versa), plug into a generator, or connect to a home outlet.

Can you use a 30-amp generator with a 50 amp? ›

The simple answer to your question, ignoring the many other worthwhile discussions that must be had, is yes. If you install a 50A inlet and buy a 30A generator you can use a suitable cable to plug it in.


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