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Niki, you said "As I noticed, all the 120V machines/tools in USA have a maximum of 15A that is 1800W."
While a 15A circuit is the most prevalent standard circuit in the USA there are 20A circuits that are, uh, not uncommon. They are quite frequently found in commercial and industrial facilities and sometimes in residences for kitchen and garage use where higher amperage equipment might be used. The connectors for 20Amp cicuits are, well differnent. Where the normal 120V 15A outlets NEMA type 5-15 have parallel vertical slots and the plugs have parallel vertical blades, the NEMA type 5-20 20A plug has one blade vertical and the other blade horizontal. The 20A plug is used for equipment drawing in excess of 15A but less than 20A, and can only be plugged into a 20A outlet.
But the 20A outlets have one vertical slot and one slot that is a "T" and thus will accept both 15 and 20Amp plugs, allowing you to mix loads using multiple lower amperage devices or use a single 20Amp device.
There are also plugs for higher amerage 120V circuits defined but I rarely see them used. Since 220V is commonly available and runs at lower currents it makes more sense from a wiring gauge point of view to use them where higher power loads are used. For the record, In the US. homes ARE wired for 220V, but mostly to permanently installed and wired equipment such as cooking ranges and ovens, water heaters, air conditioning and heating. We also use 220V outlets and plugs for portable air conditioning and heating equipment and electric clothes dryers.
Unfortunately the original power decision was made for the US to use 120V in residential appliances and the standard stuck. IIRC they were trying to pick a voltage which was non lethal but it turned out that it can be. In Europe they chose 220V at a later time and that turned out to be a really better choice, if ever so slightly more lethal. I have wondered whether any studies have been done to find if there are more accidental electrocutions from 220 vs 110 in corresponding countries of similar economic standards (such as USA vs. UK or France).
Certainly some of our power tools would be less limited in power if 220V/15A were the standard branch circuit here.
Of course Europe made the choice of 50 Hz as the standard line frequency which in my limited thinking is inferior to 60 Hz...
Induction motors run slower, light flicker and TV flicker is more obvious, linear power supplies are bigger and heavier. Of course the last two are more or less moot these days of digital TV and switching power supplies.
While a 15A circuit is the most prevalent standard circuit in the USA there are 20A circuits that are, uh, not uncommon. They are quite frequently found in commercial and industrial facilities and sometimes in residences for kitchen and garage use where higher amperage equipment might be used. The connectors for 20Amp cicuits are, well differnent. Where the normal 120V 15A outlets NEMA type 5-15 have parallel vertical slots and the plugs have parallel vertical blades, the NEMA type 5-20 20A plug has one blade vertical and the other blade horizontal. The 20A plug is used for equipment drawing in excess of 15A but less than 20A, and can only be plugged into a 20A outlet.
But the 20A outlets have one vertical slot and one slot that is a "T" and thus will accept both 15 and 20Amp plugs, allowing you to mix loads using multiple lower amperage devices or use a single 20Amp device.
There are also plugs for higher amerage 120V circuits defined but I rarely see them used. Since 220V is commonly available and runs at lower currents it makes more sense from a wiring gauge point of view to use them where higher power loads are used. For the record, In the US. homes ARE wired for 220V, but mostly to permanently installed and wired equipment such as cooking ranges and ovens, water heaters, air conditioning and heating. We also use 220V outlets and plugs for portable air conditioning and heating equipment and electric clothes dryers.
Unfortunately the original power decision was made for the US to use 120V in residential appliances and the standard stuck. IIRC they were trying to pick a voltage which was non lethal but it turned out that it can be. In Europe they chose 220V at a later time and that turned out to be a really better choice, if ever so slightly more lethal. I have wondered whether any studies have been done to find if there are more accidental electrocutions from 220 vs 110 in corresponding countries of similar economic standards (such as USA vs. UK or France).
Certainly some of our power tools would be less limited in power if 220V/15A were the standard branch circuit here.
Of course Europe made the choice of 50 Hz as the standard line frequency which in my limited thinking is inferior to 60 Hz...
Induction motors run slower, light flicker and TV flicker is more obvious, linear power supplies are bigger and heavier. Of course the last two are more or less moot these days of digital TV and switching power supplies.
Loring in Katy, TX USA
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