Does the Voltage or the Amperage Kill You?
I hear the following phrase a lot It's the amperage that kills you not the voltage While there is truth to the statement it is sort of like saying “it's the size of the vehicle not the speed that kills you when it hits you”… OK so that's a pretty bad example, but hopefully, it […]
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3 Phase Voltage Imbalance
Keep in mind when reading ANY article about electrical theory or application is that it only scratches the surface of the topic. You can dedicate years of your life to understanding electrical theory and design the way many engineers do and still know just enough to be dangerous.  In HVAC we rarely need to have a […]
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Beware of “Ghost” Voltage
Disclaimer: Ghost voltage is a term used by techs to explain a phenomenon where they measure voltage they don't expect or when the voltage they see doesn't do the work they expect. More advanced techs know how to use the Lo-Z (Low impedance) mode on their volt meter if it has one to help eliminate […]
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Does a Motor Draw More or Less at lower Voltage?
Have you ever noticed a blower motor rated for 120V draws about twice the amperage of  the same horsepower motor rated at 240V? This is because motors are rated in Watts or Horsepower and according to Watts law Watts = Volts x Amps. In order to keep the Wattage output the same at 120V, it draws […]
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Multimeter Categories
Testo 760 Category IV Multimeter I was standing at a booth at the HVAC Excellence Educators conference, and an instructor walks up, grabs a meter, and asks me, “What's the difference between a category 3 and a category 4 meter?” Well, I really wasn't sure, but I knew that the category 4 meter is rated […]
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Testing Run Capacitors the Smart (and Easy) Way
When testing a run capacitor, many techs pull the leads off and use the capacitance setting on their meter to test the capacitor. On a system that is not running, there isn't anything wrong with this test. However, when you are CONSTANTLY checking capacitors as a matter of regular testing and maintenance, that extra step […]
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