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US apppliance power limits

Discussion in 'General Electronics Discussion' started by headingwest, Sep 26, 2012.

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  1. headingwest


    Sep 26, 2012

    I'm designing an appliance controller and need to rate my triacs. What is the maximum amperage for a domestic appliance in the US on a standard circuit?

    It's easy in Australia, you can have a maximum 2400W on 240V = 10amps.

    But I can't find the same guidelines for the US.

    Thanks for your help.
  2. GreenGiant


    Feb 9, 2012
    depends, there are circuits that go all the way up to 100A plus, those are rare though, and for anything 50 or above you need a special plug

    Though the triacs should be rated at the amperage you are going to be drawing through them, not the max amperage of the circuits
  3. BobK


    Jan 5, 2010
    Typical wall outlets in the U.S. are either 15A or 20A. I think any appliance with a normal plug is actually limited to 1500W or about 14A. Now if you are talking about an electric stove or dryer that is likely to be the 50A range that G.G. mentioned.

  4. CocaCola


    Apr 7, 2012
    As has been said, the normal outlets in the use are 110-120V @ 15A, there is the optional 110-120V @ 20A circuits, these 20A circuits are generally only found in new construction in kitchens or garages, VERY few older houses have them... Thus 1500W as Bob stated is about the max for any universal plug in item... But, do note that even 1500W is technically pushing it as very few houses have dedicated lines and share the same 15A circuit across multiple sockets... Thus as anyone in the US can likely tell you using items like hair dryers that do draw upwards of the max will and can be very annoying as they trip circuits that are shared all the time... The 15A and 20A 110-120V sockets share a common plug design in most cases just rated higher, dedicated 20A appliances will have the plug switched up...

    When you get into fixed (or generally fixed) appliances like stoves, cloths dryers, water heaters or other potentially power hungry devices dedicated 220-240V lines will be run, these will range anywhere from 10A to upwards of 100A as GG stated, dependent upon the device... When you get into these higher voltage lines there are multiple plug and socket designs with many of them being dedicated to a particular Amp range so it's easier to identify... These are generally only installed on a needed basis...
  5. headingwest


    Sep 26, 2012
    OK, interesting. That means a single standard appliance (toaster/microwave/kettle/coffee maker/hair dryer) that you buy off the shelf could potentially use the full power of a standard circuit @15A.

    In Australia your toaster/microwave/kettle/coffee maker/hair dryer is limited to 10amps and runs on a 20amp circuit so 2 appliances running at the same time.

    Thank you, my question is answered.
  6. CocaCola


    Apr 7, 2012
    Yep, and many do, or at least push the limits real close...
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