You may be in the market for a shop oriented vacuum cleaner, a table saw, or even a blender. These tools of ours all plug into the wall, magic happens, and the stuff we need to get done gets done.
However, the manufacturers of these products are fooling you into wasting your money on something that isn't truly real: The Power Ratings.
Power is a very important topic in the world of science, engineering, and technology. It takes on different forms, such as mechanical, chemical, thermal, and electrical power. That being said, we will only be concentrating on electrical power. There are three main ways to describe the phenomenon of electricity: Potential Difference, Current, and Resistance. Today we will only concentrate on the first two, and they are more commonly known as Voltage (Volts) and Amperes (Amps), respectively.
When you plug an appliance into a wall, there are two things we are concerned about, the voltage and the current. Where you live makes a difference in these ratings, but most modern electronics are made to work around the world so it is of little concern (check the specs of your device to be sure).
If you live in the United States, you have anywhere from about 110-120 Volts and 10-15 Amps of current available in your standard 2 or 3 prong plug. Powerful devices, such as clothes dryers, plug into special "240 Volt" plugs that also vary a bit.
If you live in Europe, you generally have 220-230 Volts and about half the Amps of current available, although there is no easy answer as so many European countries and regions vary with their maximum current available. Overall, both systems can deliver modern electronics the same amount of power that it needs.
Power (Watts/W) = Voltage (V) x Current (Amps)
This is a very simple yet important equation for our topic. Doing the math, we see out of a standard plug we can get about 1,100 Watts (aka 1.1 kW) to 1,800 Watts (aka 1.8 kW), with about 1,440 Watts being a fair average estimate (120 V, 12 A). So what does this have to do with the Horsepower (HP) rating you will keep seeing on vacuum cleaners and such?
1 HP = ~745.7 Watts
That means from your wall socket, you cannot draw any more than 2.4 HP best case scenario, 1.5 HP worse case, and about 1.9-2.0 HP on average. Any standard appliance or tool that plugs into the wall is inaccurately rated to you if it as advertised than anything more than about 2-2.3 HP.
Now, in their defense, some companies such as Shop-Vac®, place a cutesy asterisked statement on their products, saying: "Peak Horsepower" (PHP) is a term used in the wet-dry vacuum industry for consumer comparison purposes. It does not denote the operational horsepower of a wet-dry vacuum but rather the horsepower output of a motor, including the motor’s inertial contribution, achieved in laboratory testing.
Basically, in a lab with much higher levels of electricity available, they could get the motor in said vacuum to run at a higher power. They advertise it anyway because consumers who don't know any better will assume the higher rated one is superior. In reality, it won't actually matter as you aren't able to draw that much power in the first place. So the cleaner rated at 2.0 HP and the one rated at 3.0 or 4.0 HP will perform almost exactly the same, as the motors cannot draw anymore power than the first one.
This has been a quick public service myTake, helping to make smarter and more well-informed consumers.
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