Review on Supco M500 Insulation Tester: Reliable Megohmmeter for Accurate Measurements, Includes Soft Carrying Case, 0 to 1000 Megohms by Brian Summers

I use them at work and love them. Lightweight, easy to use and reliable. This won't go into the finer details of the resistance measurement, but will tell you where the weak points are in the circuit. The lower trip point on the scale of this meter is 20 megohms, which is well above the levels I've seen in circuits that operate without tripping overloads or breakers. All of the problematic circuits I've diagnosed with my expensive Fluke test tool have shown less than 1MΩ from line to ground. Still, I love this meter because it's so light and compact. I also like that I can attach the alligator clips and have one hand free to wiggle the wires in the conduit for intermittent problems while I press the test button with the other. So far I haven't been able to misdiagnose an engine with this gauge, but when in doubt I usually use my Fluke 1507. You'll love this vixen.