Single wire, somewhere, if I read my instructions right, for AC as well as DC. For AC, that often translates into the panel.

Do you have one (clamp meter)? The good ones are spendy. I needed a DC-capable one to put together a power budget for the WRX, and I finally found one for $50 at Sears. The selector knob is a bit rough, but it seems to work. Oh, for a Fluke!