HPWC installed on lightly used 100amp subpanel. How to measure total current draw? So my model S arrives end of this week (yay) and I got an electrician out to install my HPWC the other day on an existing 100A subpanel in my garage... Based on my rough calculations, i figured that the subpanel was highly underutilized, and I'd easily be able to draw 40A to charge the car at night... However I have dual chargers and was hoping to make partial use out of them by setting up the charger DIP switches to 64A. I actually had the electrician run 100A wire and 100A breaker as well (in case of future upgrade), so technically the hardware is there to support up to 80A charging. As I understand from a previous thread, the maximum intermittent load I can draw for household items (intermittent) while the car chargers draw 64A would be 100A - (64A continuous, which is considered 80A intermittent) = 20A intermittent load. So, I got myself a clamp-on ammeter attachment (Fluke i400) which reads up to 400A AC and clamped it around the leads coming into the subpanel (the thick red, black and white wires toward the top of the image). The subpanel looks like this: From reading, I believe this is called split phase wiring, but not entirely sure. In any case, when I take current readings from each wire, each of them reads a different number of amps (thankfully quite small by the looks of it when measured late at night). The question I have is, should I simply add them all up to determine the total current being used by the panel or just the red and the black? Note: The thick black and red wires coming out of the 100A breaker set near the bottom of the image go to the HPWC.