First off, I'm not a professional electrician. I'm just a DIY homeowner who'd rather spring for the proper tools than to pay a pro to do a mundane rewiring job. When I purchased this item (the Fluke 2AC Voltage Tester), I had a couple DIY tasks in mind. The first was the need to replace a pull-chain switch on a closet ceiling lamp. Since I've never had to do this in that particular closet before, I wasn't sure which breaker switch controlled the power. Because the existing switch was broken in the off position, I couldn't very well depend on the lamp to tell me whether the power was still on or not, so I moved to Plan B  a voltage tester. I didn't need all the bells and whistles the pros use. I just needed something to tell me if a wire was hot or not. This was a perfect solution. It's got the perfect level of sensitivity for a job like this. I even pre-tested it by placing the tip against an appliance power cord that I knew had current running through it, and sure enough, the device lit up as it should. That allowed me to proceed with confidence when I repaired the pull-chain switch. Worked perfectly. The closet is now as well lit as ever.