What Size of Generator Do I Need To Run An Inverter Welder?

An inverter welder is a key machine to have in your home and on a construction site. Whether you are looking to weld your garage gate, weld fittings of your greenhouse, or are a contractor at a construction site with a demand to weld different metallic structures; an inverter welder is what you need. The question may be, what size of generator do I need to run an inverter welder.

You can solve most construction and maintenance issues related to metalwork with an inverter welder. It is an easy-to-use machine ideal for both novice and skilled users. Because of its portability, an inverter generator requires a portable power source which is a generator.

So, how do you choose the right size to power your inverter welder? It is a common question to anyone looking to invest in an inverter welder.

The right size generator you will need to power an inverter welder will depend on the welding’s power, among other factors. The inverter welder has several in-built properties that are only suitable with a particular size of a generator or the welder’s optimal performance.

Read on to learn how to choose the right size generator for your inverter welder.

When looking for the best size generator for your inverter welder, there are several aspects that you need to put into considerations; they include:

  • The generator power
  • The maximum amperage of the inverter welder
  • Width of the electrodes you wish to use
  • The compatibility of the generator with the welder machine

Generator Power

You need to know how much power the generator produces to match your inverter welder’s power requirements. Most generator manufacturers indicate the power output of their specific units in the technical passport.

This makes it easier for buyers to tell the power output of these machines. While looking at the technical passport, you should be careful not to confuse kW and kVA units (kW is the active power, and kVA is the rated power).

Additionally, you should also check the starting and running wattage of the generator. It is important to note that the ideal generator’s power will be subject to the power needs of the inverter welder you intend to run.

You should choose a generator that has 30-50% power above your inverter welder. This is because constantly using a generator at its maximum may not deliver a constant power supply.

Therefore, the best generator for an inverter welder should have a wattage of about 1.3 to 1.5 times higher than the welder’s required wattage.

If the wattage of the inverter welder is no provided, here is how to calculate it;

Wattage = Input voltage (of the welder) × Output Amp

Maximum Amperage Of The Welder

It is the maximum current that should run the inverter welder. The generator you are going to settle for should have more amperage than what the welder requires. Even so, the input voltage and amperage of the inverter welder are determined by the welder’s versatility.

Here is an easy analysis to follow;

  • Welders that require 16Amp current need a starting wattage of 3500W
  • For 22Amp current, they will need a starting wattage of 4900W, while 27Amp circuit current will require a minim of start-up current of 6kW.

For inverter welders with low amperages, such as 90Amp, they will require a starting wattage of about 3000W.

Knowing the amount of current required to keep your inverter welder running will help you make the best choice of a generator for your welder. You can find the inverter welder’s voltage and amperage figures on the user manual or on its data plate.

Width Of The Electrodes You Will Be Using

The diameter of the electrodes you will be using will determine the minimum power that the generator should deliver. Here is how to match your electrode and minimum generator power:

  • An electrode of 2mm is compatible with a generator that produces a minimum of 2.5kW
  • 3mm is consistent with a minimum of 3.5kW
  • 4mm electrode should be coupled with a generator of 4.5kW and above.

To determine the minimum power required to run the inverter welder, you should add a 0.5 on the electrode’s diameter.

The Inverter Compatibility

It would help if you ascertained that the generator you are settling for is compatible with the inverter welder. The unit should come with compatible output sockets for connecting your inverter welder. For a domestic inverter welder, you need a generator that has 220V outlets.

However, for heavy-duty usage, you will need a generator with a high voltage output 380V-this with a 3 phase voltage that comes with matching types of outlets.

 It is also important to factor in whether you will be using the generator to only power your inverter welder or use it alongside other electrical appliances.

Sometimes you may wish to recharge your smartphone or even laptop when your inverter welder is running, and if this is the case, you need to be careful when selecting your generator.

Voltage spikes can damage sensitive electronics. It would be best if you went for one that produces a clean sine wave, and it should have a total harmonic distortion of less than 5%.

You can also use the total harmonic distortion level to determine the quality of the generator you are investing in. A quality generator for running an inverter welder ought to have a power output with a low total harmonic distortion (THD).

The leading generator manufacturers in the market have specifications on their passports about their products’ THD ratings. Generally, generators with a rating of less than 6% THD are considered to produce relatively clean power, ideal for inverter welders.

Generators with more than 6% THD levels are deemed risky to running inverter welders; such units are regarded as inferior quality.

If you are using the inverter welder frequently, you should go for a generator with an Automatic Voltage Regulation (AVR) technology. Such generators can be costlier than ordinary ones. However, they have superior voltage regulation and output as well as clean power.

Other factors to consider in the selection of generator for powering an inverter welder are;

  • The fuel source for your generator: Generators used to run inverter welders are either fueled by diesel or gasoline. Among the two, gasoline-fueled generators are ideal for lighter loads. Gasoline generators have motors that generate a high-quality voltage that has the least power surges. This explains why gas generators are preferred for domestic welding needs, and they are expensive. On the other hand, diesel-powered generators are for big workloads and can power inverter welders for longer hours than the gasoline models; they are powerful generators. Do not go for a diesel-powered generator if your inverter welder is for domestic use. If your power demands are 10kW, then it’s beneficial to buy a gasoline-fueled generator.
  • Does it come with a fuel display? Low fuel levels can negatively affect the power supply of your generator. In a worse scenario, if the fuel runs out while your inverter welder is powered on, it may damage the welder and the generator. However, this can be avoided by a fuel meter or display that will display the fuel level and alert you when you need to refill the generator.
  • Level of maintenance required: The superiority of a generator rests on its maintenance status. A generator that demands high maintenance levels will no perform to your expectations if it is not serviced regularly. The best option should be a high-performance generator that requires low maintenance levels.
  • Portability: How portable is the unit? An ideal generator for an inverter welder should be mobile. This means it should be lightweight and have the features of being movable, have flexible handles, and if the unit is heavy, having non-flat tires will enhance its movability.


Is A Small Generator Ideal To Run Your Inverter Welder?

While an inverter generator may be powered by small generators such as one with 5kVA, it is not advisable. Here is why you need a considerable big generator for your inverter welder;

  • Running your inverter welder on a small generator means that the generator will struggle to maintain the high power required by your inverter welder. Such struggles may lead to power spikes, which can be the origin of the generator’s frequent shutting down or, worse, damage your welder.
  • Low power output can be frustrating to the user since the welder will not be working optimally.
  • With a small generator, you cannot rely on it to power other tools alongside the inverter welder; otherwise, it may further the above challenges.

While buying a big generator may be expensive for you, the right size or a generator with more power output than what your inverter welder consumes will reduce the risks of damaging your inverter welder.

The Do’s And Don’ts Of Using A Generator To Run An Inverter Welder

  • Before starting up or shutting down the generator, ensure the welder’s power lead is disconnected from the generator. It will safeguard your power tools from damages caused by power fluctuations.
  • Ensure the generator has an adequate amount of fuel whenever it is running. The generator should not shut down because of low fuel when the inverter welder is connected.
  • Keep the generator in its best state by ensuring that it is serviced frequently.
  • Ensure you are using quality power cables; heavy-duty are recommendable.


Frequently Asked Questions

  1. Are inverter welders any good?

Inverters’ efficiency gives them the ability to generate a more stable arc compared to conventional welding machines. Therefore, inverter welders are good. They are more stable and efficient.

  1. What size generator would I need to run an inverter welder at 120 amps at 120V?

It is advisable to use a generator that produces up to 1.5 times more output voltage than the inverter welder’s input voltage you want to run. Thus, an inverter welder with an input voltage of 120V can be comfortably powered by a generator producing up to 180V.

However, a 168V generator would still power; this is 1.4 times higher than the welder input voltage. In terms of wattage, you will have to get the product of 120amps × 120V= 14,400 watts. To comfortably power such an inverter, you will need a generator that produces 14,400 × 1.5 = 21,600 watts.

  1. Can I repair an inverter welding machine by myself?

With the high voltage and currents in an inverter welder, you cannot repair such units by yourself if you are not a certified technician. Even so, there are various tutorials online that you can keenly follow to do some minor repairs on your inverter welder.

  1. Why my welder won’t strike an arc?

Their many reasons can lead to this; however, the main reason could be unclean or unclear connection points between the welded metal pieces and the welder. Other issues could be polarity, poor wiring, and poor work lead clamp connection.

The solution is to clean the connection points where you want to arc and clamping. Remove rust, paints, and any debris on these points.

Secondly, check on your connections and ensure that the wires are in a good state and the wiring is okay; provide the grounding is also okay. Lastly, check on polarity; this is the positive and negative pole connection.

Final Thought

There are numerous sizes of generators that are compatible with different inverter welders.

However, before rushing for any of the generator models, check on the wattage of your inverter welder first. This will guide you on narrowing down to the ideal size of generator for powering your inverter welder.

You can choose a gasoline or diesel generator based on your workload, whether you are doing heavy/commercial welding services or domestic.

A gasoline-fueled generator is suitable for domestic welding needs since it produces high-quality power with minimal surges, and it is also perfect for power needs of up to 10kW.

On the other hand, a diesel generator is suitable for large-scale welding needs. It can run for long hours, generate high voltage power, and diesel is also more affordable when compared to gasoline.

Knowing your needs will help you make the best choice of a generator for your inverter welder.







About Steve Stuart

Steve Stuart is an electrical engineer who developed interest on generators during his school years. After school, he became a generator enthusiast. This is after encountering power supply problems at the area of residence where he lived. Power would be on and off and so food would go bad and the room heater would go off especially during winter. After trying the different generator brands for several years, Steve now provides information on the available brands and products in the market today. Based on his experience, he gives the do’s and the don’ts when it comes to generator use.

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