{"id":49,"date":"2010-05-27T10:37:09","date_gmt":"2010-05-27T15:37:09","guid":{"rendered":"http:\/\/blog.richmond.edu\/physicstrawick\/2010\/05\/27\/vampire-power-unplug-the-cable-box\/"},"modified":"2010-08-30T08:18:23","modified_gmt":"2010-08-30T13:18:23","slug":"vampire-power-unplug-the-cable-box","status":"publish","type":"post","link":"https:\/\/blog.richmond.edu\/physicstrawick\/2010\/05\/27\/vampire-power-unplug-the-cable-box\/","title":{"rendered":"Vampire power: unplug the cable box!"},"content":{"rendered":"

The other day I became curious about how much power was being used by various electrical appliances in my house.\u00a0 In particular, I was curious about “standby power<\/a>” or “vampire power”: the electrical power drawn by devices when they are idle or even completely turned off.\u00a0 So I stole<\/strike> borrowed a digital multimeter from work, connected it to an extension cord (had to cut open the cord), and voila–my own power meter<\/a>!\u00a0 To get the power usage in Watts, I measure AC current (amps, rms) and multiply by 120 volts.<\/p>\n

The results surprised me!<\/p>\n

First, the good news: the little power supply that I use to recharge my cell phone is actually quite efficient.\u00a0 With no phone plugged into it, it draws only 0.0009 amps, for a power consumption of about 0.1 Watt.\u00a0 At 10 cents per kilowatt-hour, that works out to about 10 cents per year.\u00a0 I still unplug it when not in use, just out of habit, but leaving it plugged in clearly wouldn’t ruin either me or our planet.<\/p>\n

Next, the bad news. \u00a0 Many other power bricks were very inefficient, drawing 4 to 6 Watts even when hooked up to no load!\u00a0 Other appliances clearly have similarly inefficient power supplies inside them, like my Braun coffee maker, which draws 3.5 Watts even when it’s turned off–all to run a stupid little LCD clock which I’ve never even bothered to set to the correct time.\u00a0\u00a0 Other losers were a boom box (6.8 watts when off) and a pair of computer speakers (7.9 watts when off).<\/p>\n

Why are some of these so bad?\u00a0 The answer, unfortunately, seems to be just bad design.\u00a0 Old style power supplies often use transformers to step down the voltage from the 120 volts in a standard outlet to the handful of volts needed for the appliance.\u00a0 These are the large, heavy black bricks that often feel warm to the touch when they are plugged in.\u00a0 By contrast, the small power brick for my cell phone feels very light; it uses silicon-based electronics instead of the heavy iron-core transformer, and is much more efficient.\u00a0 When the phone isn’t plugged in, the power supply doesn’t feel warm at all.<\/p>\n

But the single worst offender was my cable box, made by Motorola and supplied to me by Comcast.\u00a0 When it’s on, it draws 35 Watts.\u00a0 But when it’s off, it still draws 34.5 watts!<\/strong> That’s costing me an extra $30 per year, for absolutely no benefit to me.\u00a0 That’s\u00a0 unconscionable!<\/p>\n

The solution is simple: I have now put several of the worst offending devices on power strips with off switches.\u00a0 Now when they’re off, they’re really off.\u00a0 \ud83d\ude42\u00a0 With a small amount of effort on my part, I should easily be able to save about $70 per year, which of course also reduces my carbon footprint and is generally good for the planet.<\/p>\n

Do you have a story or question about “vampire power” you’d like to share?\u00a0 Leave a comment and let me know.<\/p>\n","protected":false},"excerpt":{"rendered":"

The other day I became curious about how much power was being used by various electrical appliances in my house.\u00a0 In particular, I was curious about “standby power” or “vampire power”: the electrical power drawn by devices when they are idle or even completely turned off.\u00a0 So I stole borrowed a digital multimeter from work, … Continue reading Vampire power: unplug the cable box!<\/span><\/a><\/p>\n","protected":false},"author":21,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-49","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/blog.richmond.edu\/physicstrawick\/wp-json\/wp\/v2\/posts\/49","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.richmond.edu\/physicstrawick\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.richmond.edu\/physicstrawick\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.richmond.edu\/physicstrawick\/wp-json\/wp\/v2\/users\/21"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.richmond.edu\/physicstrawick\/wp-json\/wp\/v2\/comments?post=49"}],"version-history":[{"count":0,"href":"https:\/\/blog.richmond.edu\/physicstrawick\/wp-json\/wp\/v2\/posts\/49\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.richmond.edu\/physicstrawick\/wp-json\/wp\/v2\/media?parent=49"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.richmond.edu\/physicstrawick\/wp-json\/wp\/v2\/categories?post=49"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.richmond.edu\/physicstrawick\/wp-json\/wp\/v2\/tags?post=49"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}