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

[sanrokumaru]

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.

 

[berkeman]

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.

 

[russ_watters]

A few (up to 10?) percent, though it depends on the transformer. Household appliance transformers often burn 10-20w while idle.