A visible spark at the conclusion of the probe will suggest a defect. With respect to the DC tester, there will even be a purple light-weight alarm signal, a drop in output voltage, as well as an audible sign. For anyone who is using an AC product, a blue corona https://www.facebook.com/permalink.php?story_fbid=pfbid02ga1XQfg67Uu6MdqsATSBwtcNsHo4NQDiNfcTq2b7h1KonJ7PrW4GBAQR5Jv4Afxcl&id=61560512640678&__cft__[0]=AZUJEtzJpmKmFo0QnUsEoydHoQ__PTGaobtygjrDWFjnm51uJUxM0nJamc_6KMQ5zKhDNBTehfmLE6SXLnJVsIVMplBnJLEt0XFAvkIl64nAs_N5C9s7HvLcOSJ6lYeDsOWU1bm_OdN4zmW6k1P7WA5hl7r0C81z0yQAHW-fgd4c5Qj9aqp75tR2DxVy_Y876Lc4N5Nc5O-uE6jOdb8MO6_S&__tn__=%2CO%2CP-R