The wattage of a generator is the amount of power it can generate. But what are generator starting watts or running watts? How do these parameters affect the performance of the generator? How do these terms impact the generator size selection while making a purchase? In this Generator Starting Watts vs Running Watts comparison guide, let us see everything you need to know about a generator’s starting and running watts. After reading this guide, you will understand the importance of these wattage ratings in your buying decision.
A Brief Note on Generators
A Generator is an electromechanical device that produces electricity with the help of a mechanical source such as an internal combustion engine. As the engine works, it rotates the rotor of the alternator. This action causes the rotor to create a rotating magnetic field in the stator. As a result, it induces a voltage in the windings of the stator and produces electricity in the form of alternating current. There are different types, shapes, and sizes of generators such as Stand-by generators, portable generators, inverter generators, etc. to name a few. We can also classify Generators based on the fuel they use to operate. The three most popular types of fuels are Gasoline, Propane, and Natural Gas. Regardless of the type of generator, the important specification that you must focus on is the power output of the generator. Different manufacturers have different names for power-related terms. You will see/hear terms such as rated watts, peak watts, starting watts, and running watts. Here, the terms Rated Watts and Peak Watts are usually associated with the generator while the terms Starting Watts and Running Watts are associated with the device or appliance that we want to power using the generator. But we often use them interchangeably. In the next section, we will see more information about Generator Starting Watts vs Running Watts.
What is the Wattage of a Device?
Before understanding Starting Watts and Running Watts, let us quickly take a look at the wattage of a device or appliance and also how to calculate it. In the U.S., the typical household supply is 120V AC. There are ways to get 240V (and there are some large appliances that run on 240V), but for this discussion, we will stick with 120V. When you plug an electrical device such as an electric iron into an outlet, it draws some currents to operate and we call this the amperage of the device (as we measure it in Amperes). Now, if the electric iron draws 10 Amperes (we can also represent it as 10 Amp or simply 10A), we can calculate the power in watts (also known as the Wattage of the device) by multiplying the voltage and the current. As the supply voltage, in this case, is 120V, the wattage of an electric iron is 120V × 10A = 1,200 Watts (or simply 1,200W).
Generator Starting Watts vs Running Watts
Now take a refrigerator as an example. When you turn it on, the power draw by the refrigerator is two to three times more than what it requires to operate normally. As the voltage is fixed at 120V, there is a huge surge in the amperage of the refrigerator, just for a couple of seconds. The power that motor-based appliances need while starting (or when you turn them on), is often known as Starting Watts of the device. It is also known as Surge Watts, as this high power draw is just for a short period. Once the refrigerator starts and the motor (or the compressor in this case) stabilizes, the power draw drops to a much more normal value. This, we call the Running Watts of the device. Running Watts of a device is the power it needs while operating or running normally. We said all “motor-based” appliances have Starting Watts. Is this true? Yes. Devices such as air conditioners, refrigerators (or freezers), heat pumps, water pumps, washing machines, dryers, dishwashers, garage door openers, etc. all have some form of a motor in them. Coming to tools, most power tools also have motors in them. Electric Drills, Saws (Circular, Miter, Table, etc.), sanders, air compressors, etc. all have motors. When you start any of these motor-powered devices, there will be a surge in the power for two to three seconds as the motor tries to start to pick up the pace. This power will be two to three times the running watts (or even more). The reason for this high power draw is the high surge current (also known as inrush current) that the motor draws to start from a stop position. Once the motor reaches its ideal speed (ideal in terms of its operating conditions or settings), the current falls quickly and remains more or less the same. This concept of “surge” current applies only to motors and therefore, all motor-based devices. So, in the previous example of electric iron, when we say 1,200 watts, it is the running watts of the iron and there are no starting watts in this case. Similarly, other devices and appliances such as light bulbs, heaters, microwave ovens, coffee makers, toasters, TV, Speaker systems, computers, etc. do not have starting watts but only running watts.
In the context of a Generator
When you are browsing generators (either online or in brick and motor stores), the first thing you need to look at is the output power of the generator. This is where the confusion begins. With most generators, you will see two ratings associated with power. The first thing is the Rated Watts. This is the power output of the generator (obviously in watts) that it produces for the normal operation of all the appliances. It is also known as Continuous Watts or Running Watts. Another rating is the Surge Watts, which is also known as Peak Watts or Starting Watts. It is the short burst of high power that the generator can provide to start motor-based appliances. Usually, a generator’s Starting Watts or Peak Watts rating will be more than its Running Watts or Rated Watts.
Importance of Generator Starting Watts and Running Watts
Before connecting any motor-based appliance to a generator, the important thing you need to check is if the generator can provide the necessary surge power or not. For example, you calculated the total power requirement for all the devices you want to run is around 5,000 watts. There are a couple of motor-based appliances here (a refrigerator and a water pump). Without considering the Starting Watts of these two devices, you came up with a total power consumption of 5,000 Watts. If you bought a 6,000-Watt generator based on this calculation, then you are in trouble. There will be a circuit breaker that monitors the current through the receptacles. But if the surge current (while you start the refrigerator or the pump) is more than the rating of the circuit breaker, then the breaker might trip. If you don’t take surge power or Starting Watts of a device into consideration, then you can damage the appliance, the generator, or in the worst case, start a fire. So, always take the Starting Watts (peak or surge power) of the device or appliance for calculating the size of the generator. In a later section, we will see a simple procedure to calculate the power capabilities of the generator.
Wattage Reference Guide
As a bonus, we are listing the running watts and starting watts of some common household and workshop devices, appliances, and tools. Note that these numbers are just the typical values for a particular product and the actual values will vary from one product to other. Another important thing you need to note in this table is that the column referring to the Starting Watts is actually the additional wattage of the device that it requires while starting.
What Size Generator Do I Need?
We made a dedicated guide on how to calculate the size of the generator. But on a brief note, you can calculate the power requirements and essentially, the size of the generator with the help of the Running Watts and Starting Watts of all the appliances. Assume you want to power a few incandescent lamps, a refrigerator, a microwave oven, a 43” LCD TV, and a small portable air conditioner with your generator. The following table indicates both the starting watts and running watts of all these devices. These are just typical values. From the above table, we can easily calculate the total power consumption of the electrical appliances or devices. Just add the running watts of all the devices and also add the largest starting watts value. In this example, the total power is 300 Watts + 600 Watts + 1,000 Watts + 80 Watts + 900 Watts + 2,700 Watts = 5,580 Watts. So, you should pick a generator that can provide a Peak power of 5,580 Watts and running power of 2,880 Watts. We explained in detail the steps you need to follow in selecting a proper generator size in the “How Do I Calculate What Size Generator I Need” guide. Check that out for more information.
Popular Generators with their Starting Watts and Running Watts
In the previous section, we saw that both Starting Watts and Running Watts of both the device or appliance and the Generator are equally important. As a bonus, we collected some of the popular portable generators along with their Starting Watts and Running Watts.
Conclusion
Portable Generators are very handy devices during emergencies. They can provide electricity to you and your family during power outages. While “home” generators are mainly used for power backup during blackouts, we can also find generators in camping, construction, and work sites. 8,750 Watts (Natural Gas) 7,000 Watts (Natural Gas) Regardless of the setting (home, RV, or work), the purpose of the generator is to provide electricity without depending on the grid. When you are browsing for generators, you will come across important specifications associated with the power output of the generator. The two common terms are Starting Watts and Running Watts. These two values indicate the power capabilities of the generator for starting motor-based devices and normal running of appliances. In this guide, we saw the basics of Generators and a brief note on wattage (and how to calculate it). After that, we understood the terms Staring Watts and Running Watts and the importance of Generator Starting Watts vs Running Watts. Later, we saw a table listing the peak power (surge power or starting watts) and continuous power (rated power or running watts) of some common household and workshop devices, appliances, and tools. By using the Generator Starting Watts and Running Watts, we saw how to calculate the size of a generator. As a bonus, we listed some popular generators with their power ratings. We hope that this guide on Generator Starting Watts vs Running Watts could help you understand the importance of these power ratings while purchasing a generator. If you feel we missed something or want us to add anything, do let us know in the comments section. It will not only help us but also other readers. Comment * Name * Email * Website
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