Arkansas HVACR NewsMagazine November 2019

S tate, National, Chapter News Tech News

Now, this is a hypothetical situation, but you will notice that the poor connection is AFTER the contactor coil in what we call the common circuit in 24v controls. It doesn’t matter WHERE in the circuit resistance is added, whether before the switch (in this case a thermostat) in the line side or after the switch on the load side. It could even be in common or in the switch itself. Anytime additional resistance is added to a circuit it results in voltage drop when the circuit is intact. When we disconnect wires to test voltage or test voltage with a circuit that has an open switch we can create confusion and observe “ghost” voltage. In reality it is simply extreme voltage drop caused by additional resistance in Bryan is a lifelong learner, proud technician and advocate for the HVAC/R Trade. This article originally appeared at https://www.hvacrschool.com/beware-ghost- voltage/?utm_source=TechTips&utm_campaign=32 73296894- RSS_EMAIL_CAMPAIGN&utm_medium=email&utm _term=0_608fe06f1d-3273296894-64230413 Many thanks to David Stephenson, NW Chapter President, for pointing out this article. If you have articles that you think will benefit your friends in HVACR, just drop us a note at news@arhvacr.org . We’ll get it published. series with the load. — Bryan Orr ( Founder / Podcaster / Dad of 10 )