A fun curse you get when you spend long enough looking at consumer electronics is automatically figuring out roughly how much power something uses. This is useful sometimes: if you know your laptop sucks down about 8 watts while browsing the web, and you have a 40 watt hour battery, you know you have about 5 hours of battery life. If you know that you only have 50 kilowatt hours left in your prepaid electricity meter, you can estimate whether you need to buy more now or if you can let it slide until tomorrow, by tallying up everything that’s running.

It also makes you develop strange opinions and heuristics. This electric heater pulls 2000W which means it costs about ZAR 2 per hour to run. All the stuff plugged into my desk runs an estimated 150-200W depending on how much computing I’m doing, so that’s ten times less than that. My lights are 4×5W or 20W so that’s ten times less than that. If I decide that, to account for my convenience, I should turn off my lights if I’m leaving the room for more than 10 minutes, I should sleep my computer if I’m leaving the room for more than 1 minute. This is of course, nonsense, the convenience factor here is not fixed, but that doesn’t mean I don’t think about it every time I turn off my lights but leave my PC on.

If you happen to know that the rated power for a single wall plug (in South Africa) is about 3700W, then you also start to see danger where most people do not. Most people learn that the dangerous thing about power strips is that you can plug in too many items and that’s mysteriously dangerous somehow, but the REAL danger with power strips is that they put the full load of everything plugged into them onto a single wall plug. Daisy-chained power strips with 40 cellphone chargers plugged in is relatively safe. A power strip with two electric heaters plugged in is a recipe for disaster, and will pull excessive current in basically any house on earth. That’s how you get house fires.

(Note: in the USA your plugs are rated at only 1875W per plug (or maybe 2500W, depends on the plug), so many appliances such as hair-dryers, heaters and other high-power devices are only safe to use if they are the ONLY item on a wall plug. Multiple-slot extension cords have a much higher risk of exceeding minimum safe levels in this situation compared to countries with higher voltage wall power.)

If you ever find yourself wandering aimlessly through the appliances aisle of your home goods store, muttering about rated versus nominal current and trying to estimate how long per day you actually /run/ a blender and really how many days a year do you use it anyways, is it worth springing for the more efficient one? I’m sorry to say there’s nothing we can do to help you.

Technology Connections at it again with informative videos about my debilitating obsessions.


#are you telling me other people *don’t* wander around hardware stores muttering about whether to spring for the more efficient appliance? #adventures in human capitalism #the more you know #the power of science #domesticity #fun with loopholes

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