Looking at my electric bill, there’s a section saying “this percent came from [ex: Air conditioner, major appliances (fridge, oven), etc]”. How do they know that?
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All electric motors have a locked rotor amperage printed on the information plate. This is the amperage it draws when power is going to the windings (the sitty still part) but the rotor isn’t moving (the spinny part) off the rotor were rusted in place, the motor would draw locked rotor from the time power was applied until it was shut off (with larger motors that would be when the breaker trips) the compressors in most residential air conditioning systems have locked rotor amperages easily around 100 amps. Refrigerators and such, can be around 30 to 50. When you turn it on, the rotor isn’t moving. The electric field produced in the windings has to get it moving and that happens very fast, but for a split second it draws locked rotor amps. Then it will run at around 10-20 amps until it shuts off. Your furnace blower will draw 40-50 or so locked rotor amps as well for that split second. Then it will run at around 8 amps until done. Fan motors in refrigerators will draw a comparably small locked rotor amperage (maybe 10) so when they see a big spike (home a/c starting) of around 150 amps, followed by a 20 minute period of around 25 amps, they know your air conditioner is running, because virtually nothing else anyone has at their home would share that profile. A spike of around 60 amps, followed by a 20 minute draw of around 10 amps, tells them you have a refrigerator or freezer running for the same reason. The commenter who’s being told to get rid of their garage fridge, it would be because they see that profile either at two different times at intervals that don’t make sense for one appliance, or because they see it happen again while the first one is already running. For other appliances, if they aren’t cooling they’re probably heating. Toasters, electric ovens, etc draw high amperage continuously but have no spike when they start. Dishwasher’s and such draw lower amps but also have no spike. But all of those won’t be turned on for hours at a time like lights or tv’s. So they get labeled as “other appliances”
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