If you need to run an electric air compressor in a location without an electrical outlet, you will need to have a generator accessible. Many job sites will require generators to power various tools they may need, including an air compressor. The generator will need to be large enough to power the air compressor to complete the necessary projects.
What size generator do you need to run a compressor? The size of the generator you use will depend on the specific size and power capabilities. First, Examine the voltage and amperage requirements to operate to determine the working voltage of a compressor. Then Multiply this value by three as it requires upwards of 3 times the power to start.
Because there is such a wide range of air compressors with varying power requirements, the size generator you need will depend on the individual compressor you have. This article will break down the guidelines you should follow in selecting a generator that will power your compressor without choosing too big!
Choosing The Right Size Generator to Run a Compressor
With many options in compressor power outputs, you’ll first need to identify the wattage required to run and start a compressor. These values will then determine how much power is needed from a generator. Compressors typically measure their power output with different levels of horsepower, ranging from 0.5 – 6.5 HP.
The right size generator is the number of watts that slightly exceeds the starting wattage required to turn on and run your compressor. There is no set size for every generator, and the section below will show you how to calculate which will work best for your compressor.
Converting Air Compressor Metrics to Wattage
Because generators are typically characterized by wattage, you will need to determine these values for the air compressor to determine what size and power output you will need.
Most electric air compressors will stay under 2 HP, which operates with 110-120V outlets commonly found in a home. For larger compressors that run on over 2 HP, the outlet will need 220-234V outlets. This voltage impacts the size generator that will be required, with larger horsepower motors requiring larger generators.
After determining the voltage of your compressor, find the amperage. These details should be provided by the manufacturer and will be necessary for calculating the overall wattage. Compressors will often detail both their running wattage and starting wattage for you, but wattage can be easily calculated.
To calculate the wattage of your air compressor, you will need to:
Find the voltage and amperages of the air compressor: You can find these individual values in the manual or detailed by the manufacturer.
Multiply voltage by amperages to calculate running wattage: Wattage is the product of amperage (how strong an electrical current is) and volts (electrical potential that sends a certain amount of force through the circuit). This combination results in your overall electrical power or wattage.
Take running wattage and multiple by 3 to determine starting wattage: Motors need a surge of power to start, and this is often 3x the amount of power that it will need while on and running.
Use a generator that provides wattage greater than starting wattage: Make sure the generator can handle the starting wattage of the compressor so it can successfully start.
Your air compressor instructions should tell you the required starting and running wattages required to run the compressor. If those details are not noted, you can use the steps mentioned above. At least three to five times the amount of wattage is required to start a compressor as is needed to run it. Each compressor will be different, so make sure you note these individual differences.
Generator Wattage Requirements
Generators will provide power for starting watts for a few seconds, while a steady flow of power will meet running wattage requirements while using your compressor. Compressors rely on capacitor start induction motors, which require 3 to 4.5 times the amount of torque during the starting phase.
The generator you choose will need to exceed the starting wattage value of the air compressor to ensure it will start and run. Exceeding the starting wattage will keep the generator in the best shape. If you plan to run multiple tools or appliances simultaneously from the generator, you will need to consider these additional wattage values.
Larger generators are more efficient in providing power to appliances and units that require 240 volts while still providing power to 120 volts, typically by flipping a switch to change circuits. However, most small generators are more effective for 120V use and will be sufficient for most household compressor needs.
Size Options for Generators and Compressors
The specifics of the size generator needed will depend on the power provided by the air compressor. We have pulled together various air compressor variations and the corresponding generator required to start and run it. Unless you need a generator for a wide range of machinery, finding one similar in wattage requirements will save space and money.
While horsepower is not the only important metric used in selecting an air compressor, it is an important measurement of how powerful the machine is and how well it can refill a compressor tank to continue providing air. In addition, the amount of horsepower is necessary to determine how much wattage is required from a generator to start the appliance.
Comparing the HP of Compressors
We will compare different HP compressors and provide both their starting and running wattages. You should choose a generator that slightly exceeds the starting wattage value:
½ HP Air Compressor: One of the smallest air compressors, you will need 2000 starting watts and 1000 running watts. This is suitable for most renovations and home improvements, as well as crafting.
1 HP Air Compressor: 4500 watts must start this compressor, and 1500 watts are needed for running. 1 HP compressors are also solid options for home improvement projects and hobbies.
1-½ HP Air Compressor: 6000 watts for starting wattage and 2200 watts for running wattage. Driving more power than the former will allow for more powerful projects.
2 HP Air Compressor: 7770 watts for starting wattage and 2800 for running wattage. Contractors may benefit from the versatility offered by a higher-powered compressor.
We note the ½ to 2 HP air compressors because these are the power values of those most frequently sold on the consumer retail market. The trend for most of the compressors shows the 3x power needed to start a compressor versus run it off of a generator. Therefore, you will need to calculate the running wattage of the larger compressor and multiply it by 3!
Don’t Skimp on the Generator
It is recommended that you use a generator that can accommodate slightly more watts than your compressor requires. This should be followed for multiple reasons:
Play it safe: If the calculations are slightly off or the compressor reaches the generator’s capacity, you don’t want to lose power because the generator is fully engaged or exceeds wattage levels.
Versatility: To operate multiple appliances simultaneously or have the ability to power bigger machines, purchasing a more powerful generator will prevent you from needing to buy an additional one for more power.
The life span of the generator: If the generator is running at full capacity all the time, this puts more stress on the device and could result in shorter working life. To get the most out of your generator, keep the power output levels below the maximum limits.
Generators will generally offer their rated power versus their maximum power, as generators should not be run at the maximum output for more than 30 minutes at a time. Rated power is the amount of power that a device can deliver consistently and under normal working conditions.
Generator sizes will vary depending on residential or industrial use. They are typically measured in kilowatts (1 kW = 1000 watts). Residential generators can be as powerful as 50kW to power an entire house, while industrial generators offer significantly more power options, upwards of 3 megawatts! Most compressors will stay under 10,000 watts with a medium-sized generator.
Why Use A Generator to Run a Compressor?
Generators are used to provide a power source when no electrical outlets are available or offer additional power when greater power needs must be met. There are multiple reasons why you should look into a generator to run a compressor:
Remote or outdoor work: Often brought to job sites or areas far from your house, you can work on any compressor project if you have a generator to supply power nearby. If the generator is large, it may need to be transported on a cart.
Power outage: In the event of a power outage, a generator will allow you to keep working with a compressor regardless of electrical power source status. This is often used for homes in the event of power outages or emergencies.
Greater power requirements: If you need more wattage than your electrical system can provide, a large generator can give you the additional power.
Standby and Portable Generators
Generators come in two varieties, standby and portable.
Standby generators are typically designed to serve as backups for a home if you need more power during an outage. They are automatically hooked up and will provide power if your main circuits fail to do so.
A portable generator is powered by gas or propane and can be taken anywhere for use. The level of portability will depend on its size. These are necessary when electrical power is not accessible, and, in most cases, you will be using a portable generator to power your compressor. These compressors are used for both residential projects and industrial job sites.
The alternative to using a generator to run a compressor is to opt for a gas-powered air compressor. This will eliminate the entire need for electricity and provide you with power from a gas-powered engine instead. You would need to compare the cost and feasibility of using a gas device versus traditional electric models.
Safely Running a Generator with a Compressor
Any gas-powered or electrical device should be operated safely to yield desired results for power and prevent any accidents or injuries. Safety precautions should be taken with each device, especially when used in conjunction with one another. More risks are presented when you operate electrically powered tools and gas-powered engines simultaneously.
When using an air compressor, these are the necessary precautions and risks you should be aware of:
Electrical shocks: Make sure the compressor is properly plugged in, or there could be the risk of electrocution. You may also damage the equipment when these electrical problems occur. Make sure you properly follow manufacturer guidelines for plugging into a generator.
High-pressure air: When in contact with the body, a great injury may occur. Always wear appropriate personal protective equipment when operating.
Dispelled debris: Working with highly pressurized air leads to the opportunity for flying debris and objects. Be mindful of where compressed air is directed, especially concerning nearby people and surroundings.
Noise: Air compressors are very loud, so make sure you wear ear protection. This, coupled with a generator’s noise, can be very unpleasant and cause hearing loss.
It would be best to be mindful of these risks, especially when you add a generator into the mix. This is because you add another layer of danger when operating a gas-powered machine. The two can be used very safely together, but you must take precautions.
Generator Safety
To use a generator safely, you should always:
Work outside: Because portable generators are gas-powered, they emit harmful chemicals and gases, including carbon monoxide (CO). Inhaling these fumes can be very dangerous, leading to sickness (and, in severe cases, death). In addition, indoor areas do not ventilate well and could be contaminated without knowledge as CO is odorless.
Keep the generator dry: As you will be attaching electrical devices, you could risk electrocution or shock if the generator is wet. Therefore, you should properly dry the generator and not use it in rainy conditions.
Check fuel requirements: Fuel levels and composition may vary from generator to generator. Make sure you read the instructions and requirements fully before putting fuel into the generator and starting it.
Refuel while off: Make sure you turn the generator off before you put more fuel in. Vapors from the gas could contact heat or electricity and lead to a fire or explosion.
Use acceptable extension cords: If you need to use an extension cord from the compressor to the generator, you will need to make sure it is compatible with the wattages. Longer extension cords will weaken the current and typically only work with lower wattages. Please make sure they are compliant not cause damage to either device.
While the combination of safety guidelines you should follow for using a compressor and a generator is somewhat lengthy, they must remember for proper use. Most of these rules apply to electronic and gas-powered devices, making them easier to follow. However, reviewing safety guidelines before use is recommended.
When working with powerful equipment such as these, be sure to wear protective clothing and some form of ear protection. Especially if exposed to these sounds for extended periods of time, you could experience issues related to hearing loss. In addition, if using a loud generator and compressor, these increased sound levels can be even more severe.
Sizing a Generator For Your Compressor
There is no single answer for exactly what size generator that will work with your compressor.
Fortunately, the simple wattage calculation of volts x amperages will give you all the necessary information you need to find a properly sized generator. You can find these electricity measurements on the air compressor and use them to make your generator purchase.
These are the top things to remember when choosing a generator for your compressor:
Always account for starting wattage: You will need to have at least 3x the amount of wattage to account for a surge in power needed to start the compressor. After that, it will run at its running wattage, which is much lower.
Go for more wattage than you’ll need: You should always err on the side of caution and choose a generator that offers slightly more wattage than the compressor requires. This will ensure proper starting and function.
Choose a compressor for many projects: Unless you only need a generator for a compressor, consider getting a more powerful one that will allow for future appliance use or simultaneous running of devices.
A generator can make any compressor project accessible from all locations. Its portability and ease of use will allow you to complete projects, whether for hobbies and crafts, home improvement use, or larger contractor needs.