A visual spark at the end of the probe will indicate a defect. With respect to your DC tester, there will also be a pink gentle alarm signal, a drop in output voltage, in addition to an audible signal. In case you are making use of an AC product, a https://www.facebook.com/permalink.php?story_fbid=pfbid0hwBsQpkrcShPxE7GpV7pF3T7dijUVG5UrNcWVTrzp5RzoaFyhP8LoFN2wDg8oxqRl&id=61560512640678&__cft__[0]=AZXE4tuZAVwJ03hH8_b1MtDbAdH1Mq8USHo7Xt_ibv44HgWeMEiGp3zHTWRhZKF_WodEbpjpaKU50ZQUbWjH4Sab8E3cuR2gnMTaoFgdvw5aUlkoFLnBSglwAN4NNKbGjDA2Uoup63QqQC1zXFWYe2UyiqlsuTwU4R_Oz5pG0_J7NKiASgQjSTamC6WMu9xto83aBK_-Ft4B0UNBaiwUav5r&__tn__=%2CO%2CP-R