I need some knowledgeable sparky to help me understand a situation I found at an inspection yesterday. It was an exterior electric receptacle with the normal hot/ neutral/ equipment ground that is found in an everyday receptacle. The receptacle tested as dead when using a standard 3 prong tester—no lights at the tester at all. My electric sniffer then indicated that both the hot and neutral wires were both hot when it was plugged into the hot and neutral slots separately. What kind of wiring configuration could produce a scenario such as this? And why did the tester not light up at all. It is a tester I have used in the past successfully and used it at today’s inspection without any glitches.
Those sniffer testers are extremely sensitive .
The wire feeding the Receptacle could be picking up enough induced voltage from another line to give you a signal.
Could be induced or sometimes called, phantom voltage. Even an expensive DMM can be fooled. Best way to test to know for sure is with a solenoid style (Wiggy) tester.
I have written extensively about the problems associated with high input impedance testers in articles and in this forum so I will not go into much detail. The long and short of it is this - use a low input impedance tester such as a Wiggy for most of your tests. You will consistently get meaningful results. If you are interested in understanding why that is, you can participate in one of my free online classes or read the articles I have posted on my website.
I often answer the original question without looking at all the other replies. I’m glad to see I’m not the only guy out there using - and recommending - a Wiggy®! It is a tool that an electrician cannot live without. To me, not having a Wiggy would be like not having a screwdriver or a pair of shoes.
I spent many years working as an electrician while working on my electrical engineering degree and many years after that working as an electrical contractor and engineer. Over the years, I’ve owned just about every type of electrical test equipment that man has thought to make. The Wiggy has been my main troubleshooting tool in every phase of my career. Several of my Wiggys are more than 30 years old and still work like brand new.
To be sure, I still use a VOM (Simpson 260MP), oscilloscopes and other test equipment when the need arises but when it comes to power distribution troubleshooting and inspections, I have yet to have anything come up that I could not check reliably with a Wiggy.