Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Do transformers (110V-220V) drain much power?

  1. Dec 15, 2006 #1
    Hello everyone

    I have a 110V hardware plugged in at home (we use 220V) by way of a step down transformer and I was wondering if transformers 'use' more power than usual. I don't want a nasty electircal bill.

    Because even when the hardware is 'off', the transformer itself is still on. It still hums. I am wondering if the transformer is constantly pulling power out of the wall socket 24/7 if I leave it on.

    Any help will be greatly appreciated. Thanks all.
  2. jcsd
  3. Dec 15, 2006 #2


    User Avatar

    Staff: Mentor

    Yes, transformers are lossy. You can feel the transformer to see that it is warm, even with no load attached. It's best to unplug it when not in use.
  4. Dec 15, 2006 #3


    User Avatar

    Staff: Mentor

    A few (up to 10?) percent, though it depends on the transformer. Household appliance transformers often burn 10-20w while idle.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?