I just wired a blue LED on a breadboard with the anode to an Arduino Uno's 3.3V rail and the cathode to a 220 ohm resistor to ground. Then I measured the current consumption using my Fluke 87-V and it was 1463 microamps.
Here's the strange part: I then added another blue LED, exactly the same type, in parallel to the first one. This, too, was using a 220 ohm resistor. I expected the current consumption to double to 2926 microamps or so. Instad, the measured current consumption was 2121 microamps. Can anyone explain this?
Update: Just added a third blue LED, same type, in parallel, 220 ohm resistor, and the current drawn is now 2681 microamps. Wtf?
Update 2: I just switched my Fluke to the mA range and now I get 5.41 mA drawn with 3 LEDs in parallel. With two in parallel on the mA range I get 3.61 mA and with just one I get 2.02 mA. All measurements in DC mode of course. So I assume my Fluke is broken since it gives different readings on the uA and mA modes?