I see alot of people measuring power consumption with Kill-a-Watt, UPS readings, or using other devices. All along, I've been measuring my power consumption using a very cheap and simple technique.
I modified a power cable with a 1 ohm 10 watt resistor inline of the neutral wire (not the live wire, because that would be dangerous). Then by measuring the voltage drop over the resistor, you can calculate the current that is flowing and then the power consumed by whatever is plugged into the modified power cable.
Danger aside, I am just wondering how accurate this method would be compared to the other methods especially with power factor taken into account? I'll admit I wasnt paying much attention in physics class during the power factor section =( Are there other things to take into consideration? I measured the power consumption of various lamps and this method seems accurate enough.
Measuring power consumption cheaply using a resistor inline?
Moderators: Ralf Hutter, Lawrence Lee
APFC should keep the power factor well above 0.9 for normal loads (it will be much less in standby). You could try looking up a measured value for your particular PSU (the 80 Plus website is a good resource for that sort of thing).