How much electricity do those little black transformers use even if they are not attached to a device?

I am talking about those little black, block-like dc transformers that run all sorts of little electronic devices. I understand that they draw power even if the device is not attached to it. I am trying to figure out how much electricity I use a year each year since i have ten or so plugged in all the time, thanksHow much electricity do those little black transformers use even if they are not attached to a device?For the small ones it is such a tiny amount that it is difficult to even measure with ordinary equipment. Larger, regulated ones (like for a laptop) do have easily measurable current draws during idle time, but even this power consumption is pretty insignificant and will amount to only a few pennies worth of power each month. You can easily save more power by remembering to always turn off the lights when you leave a room than you can by worrying about the parasitic power of the wall warts.



WKHow much electricity do those little black transformers use even if they are not attached to a device?These little power devices, commonly called wall warts or wall bugs, don't supply a lot of power and don't draw a lot even when in use. When they are not in use, they do still draw some current, but with no load their impedance goes up and the draw on your electricity becomes very minimal.



If you have a lot of them and want to know what the total draw is, plug them into a plug strip (string two or more together if you have to) and measure the the draw with a clamp on ammeter. You could measure the draw with and without load to see what the difference is. Maybe you could borrow the ammeter or find somebody that will do this for you. It's not a big job. You do need a cord that will let you clamp around just one wire to get a reading. You can actually buy this kind of cord and clamp on ammeters are lower in price than they used to be.