A lot of stuff doesn't have a broken physical switch
PCs for example still keep the motherboard connected and powered for USB devices. THere's also a current in every extension cable and multi-gang plug due to the voltage difference along the resistance of the wire.

/uncle worked in a power station
( Grrrmachine the indifference engine, Fri 24 Oct 2008, 8:35, 3 replies)

What about the 30% decrease in power consumption
Is it likely?

/genuinely curious
( LemonEntryMyDearWatson This time, Moriarty, the hand is on the other foot, Fri 24 Oct 2008, 9:00, closed)

Ohm Eye God
no voltage drop. No voltage drop - no power loss.

/grandfather worked in a power station
/doctorate in modelling current distributions in conductors
(ubergeekian, Fri 24 Oct 2008, 10:38, closed)

there'd be *some*
but not very much.

phone chargers etc do warm up quite a bit when they're plugged in.

stupid transformers.
( catness, Sun 26 Oct 2008, 17:58, closed)

Have a look for
the +5v(B) jumper on your motherboard- you could just save yourself... well, very little (500mA @5v maximum). But some!

Also, invest in a "smart" power block that turns the peripherals off whenever the PC goes off- I reckon mine's paid for itself this year (a couple of monitors, some speakers, etc all plugged into it).

Like someone below says, there's no voltage drop in the wire, so there's no current flowing. Power is current x voltage, so there's no power loss from a mains extension just being sat there, unless it's one of the ones with a flashing light (cheap surge protected ones).

Power will, however, be lost along the wire when it's providing power to a load as current is flowing through the wire, and the wire has a resistance. This loss is approximately the square root of FA over a 2ft extension, though a surprising amount of heat can be created inside a long coil of wire carrying AC!

/Degree in Mechatronics, several damaged cable-reels.
( uberdeity Wondered why Owen Lars knew of the term "hell" on, Fri 24 Oct 2008, 17:33, closed)