How to use
Voltage testers and volt meters are two different things. A meter will provide a an indication of the exact voltage and type AC or DC. A tester on the other hand simply provides an indication of presence of power with little to no indication of how much or type.
AC power is what is provided by most power companies in the world. DC is a type of power provided by batteries and DC power supplies. If your tester or meter has provisions to check for AC and DC, you should check for BOTH. If AC power is present and you are have set your meter to test for DC power, your meter will indicate 0 volts. You can see this can be a dangerous condition. Most simple testers will not care if AC or DC power is being tested and the types that use neon lamps will usually glow differently for AC and DC power.
When setting up for testing voltage, you must test across the power source (or in "parallel") or load (such as a light bulb), as opposed to "in series" with the power source. Across would be from the + to - post of a battery, into the slots of an outlet, etc. "In series" is when the tester would be completing a circuit - such as testing across an open switch.
First, check the meter's operation by testing a known good power source by following the next steps. Set the meter for the type power to be tested. Choose AC if unsure. Next, set the meter for the highest voltage range supported. Make sure this range is higher than the expected voltage, otherwise damage to the meter may result. Connect the probes to the power source. Read the meter. If the meter moved only slightly, adjust the range of the meter to the next lower value. You can keep adjusting downward as needed to get the most precise reading possible - but do not set the range to a value less than the voltage present. A 0-300 volt scale is the lowest to measure a 240 volt outlet - switching to a 0 - 150 volt scale will damage the meter. The 0 - 150 volt scale would be fine for measuring 120 volt outlets.
If the meter did not move, change the type from AC to DC. and repeat. If it still does not work, the meter is not working correctly (if testing a know good source) or there is no power present (if the meter worked on a known good power source).
May 12, 2012 |
Measuring Tools & Sensors