In defense of the wiggy, I never use the wiggy to measure voltage. I simply use it to feel for the buzz. Small buzz = 120 Big buzz = 240. If I'm only changing devices (receps or switches), I'll use my Fluke lighty up thingie. If I want to measure actual voltage, I take out my Fluke 87 or T5-600. The Knopp brand wiggy is small and fits in my bags nicely, unlike either of my Fluke products.