Step 1: AC Measurement
For this project, I used an AC clamp. With an AC clamp, it is possible to measure the current traveling through a wire without physically touching it. Basically it is a simple transformer where the wire of interest acts as the primary coil and the AC clamp is the secondary coil. Most AC clamps are integrated into a multi-meter. I used a stand-alone type for my project. It outputs 10mV per ampere and is intended to be connected to a multi-meter. All you do is multiply the voltage reading by 100 to get the current in the wire. These can be found for $20 or less on Ebay. Mine were made by Steren, model MUL-285. The great thing about using an AC clamp is that I was able to do all of my prototyping without ever turning the power off.