Why is it that we use voltages and watts more often than amperages? 9v batteries, 12v car battery, 1000W Microwave oven. But amperages not so much, even though its “half” of what makes power, A*V=W. What property of amperes makes it so “unnecessary” to be aware of?

Bonus: how many amps and volts does a typical 1000W microwave use?

  • ggtdbz@lemmy.dbzer0.com
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    1 day ago

    USian here. My refrigerator expects (and is legally required to have) a dedicated branch circuit of fifteen or twenty amps with nothing else on it.

    Does any fridge use 1,800W? Even at peak? A small freeze-dryer? I’m holding off on making cheap jokes at the expense of American cuisine, your fridge might be legally over provisioned for some reason, but it’s not drawing this much power. My entire house idles at about 1.1~1.5A, or about 250~350W, if nothing is running but the absolute essentials. And that’s a relevant number for me, I do solar! I do batteries! Every little bit counts. Fridge is the most important thing to power, and literally everything else comes after.

    During the financial meltdown/pandemic people ran their fridges for eight or less hours a day because there was just not enough diesel. That’s the time we decided to splurge on solar. If you want more fun anecdotes, during that time I was waiting in line for 3-4 hours for fuel, and then bribing the attendant more than the value of the fuel to let me fill over 20 liters. Not fun times. And I’m someone who was lucky enough to be able to pay his way through the worst of it.

    I’m in Lebanon. I too count my blessings. It’s not culturally mandatory to strand your kids at 18 here, nor culturally accepted to have them dodge bullets at school. So you know. Even at the peak of people being harassed by Hafez’s secret police, people were not getting snatched on the street en masse. I don’t have the mental scaffolding to even begin to grapple with your reality my dear. Using the gas because the microwave is unavailable until tomorrow, temporarily stealing my neighbor’s water, angling for favor with feudal lords’ bureaucrats… Problems yes, but problems I understand.

    I hope I’m not being too mean here, the US still fascinates me in a way no other potential new home does, even with everything happening right now. How’s that for perspective.

    • xuv@lemmy.blahaj.zone
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      2 hours ago

      US electrical requirements for fridges are somewhat overprovisioned for food safety requirements, the fridge is the most important thing to power as you say. It’s easy to not notice when your fridge has lost power and US food safety law says that 4 hours in a fridge without power is unsafe, so the circuit is arranged where the breaker should never turn off in normal operation. (This is a relatively recent addition to the electrical code, most older houses will have the fridge on a mixed circuit, but that’s the reasoning)

      I’m not sure what the typical current draw for a US fridge is but they are much larger than you’re used to. The fridges currently for sale have around 18 to 30 cubic feet interiors (most houses I’ve seen have the larger end of that range), and current draw increases with size. Peak draw for refrigeration is about 4x the typical running draw so I imagine the larger ones do come close to that 15 amp rating when they turn on.