This is what I was explaining to a gentleman the other day. I was basically explaining to him that a noncontact voltage tester works off an electrostatic field. Whereas a clamp meter to sense current works off an electromagnetic field. You get an electrostatic field with the presence of voltage and you get an electromagnetic field with current flow. Michael Faraday demonstrated this phenomenon perfectly with a set of compasses placed in the proximity of a conductor that had current flowing through it in the early 19th century. This experiment also helped Michael Faraday discover the relationship between electricity and magnetism. Limited in his understanding of advanced mathematics, he commissioned James clerk Maxwell to write the famous maxwell equations explaining this phenomenon. The unit of electrical capacitance, “the Farad” is named after Michael Faraday. The unit of electrical inductance, “the Henry” is named after an electrical engineer by the name of Joseph Henry.
Well said. The study of electricity is interesting stuff. Under each layer of what you see (and know) there is always another to further explain things. I am still learning after all these years. Thank you for watching and thank you for the comment.
@@takingmeasure thank you for posting this video and your comment, sir! Yesterday I registered for my first class at the local community college to start my 4 year journey in obtaining my electrical engineering degree from Mississippi State University’s Bagley college of engineering.
Why doesn't the neutral wire activate the tester? If I measure voltage with DMM between neutral and hot I get 120V. If I reverse the test leads, I still measure 120V. i.e. both hot and neutral carry alternating current.
The neutral is a grounded conductor. Grounded wires are designed to have a low resistance path to the ground, which means they are essentially at the same potential as the ground itself. Therefore, there is no potential difference (voltage) between the grounded wire and the surrounding environment. As a result, a non-contact voltage tester will not detect any voltage on grounded wires because there is no electric field emanating from them. Put in simple terms: the electrostatic charge is not allowed to build.
Most Non-Contact testers only test AC voltages so you have to find DC voltage Non-Contact testers and also look into "insulation line break tester modes" to find a break/open in a wire harness or wire. Try making a YT lesson about using a DC non-contact tester and using the insulation line break mode to test wires, test relay contacts and test leaf type switch contacts because visually the contacts might look closed but won't have current passing through the switch contacts which the insulation line break tester will detect there is a BREAK
