Not an electrician but I have one of these. While I have used it to troubleshoot electrical problems on occasion (eg- this thing doesn’t have a power LED but I can tell it’s getting power), it’s far more useful for locating and holding small screws. The field sensing bit is somewhat hit and miss. Mine works on microwave ovens, most transformers, some models of anti-theft gate, an electric tram once or twice, and on one occasion, a laptop WiFi card.