markyoung1984 0 Posted March 9, 2008 If a normally closed circuit is a complete un-interrupted circuit, why does it show as 0 on my voltmeter, yet when the circuit is opened the voltmeter registers as 5 volts (which is what should be going through)? Could someone please explain? Thanks in advance Share this post Link to post Share on other sites
cachecreekcctv 0 Posted March 10, 2008 Just wondering if this is an electronic relay, or a set of "dry contacts". If you put your volt meter on an ordinary light switch ( as in your house-115vac), when the contacts are open, you will read your house voltage. When you turn the switch on, and close the contacts, you will not read any voltage on your meter, but, believe me, there is still 115vac on both sides of that switch. Sometimes, when you read voltage through an electronic relay , and not a set of dry contacts, you will read a small amount of voltage. Sometimes you get "bleed through" on electronic relays. Share this post Link to post Share on other sites
cachecreekcctv 0 Posted March 10, 2008 One thing, when contacts are "closed", you can only read voltage when you have both sides. To read DC voltage, with a voltmeter, you must have both Positive and Negative voltage. To read AC voltage, you must a "hot" conductor and also a "neutral" or ground. I have had to prove this many times. Turn on a light switch in your house and read what voltage across the two terminals of the switch. When you open the contacts of the light switch (turn the switch off), you are now reading hot and neutral. Just be very careful. Share this post Link to post Share on other sites
