What Does a Positive Reading Mean on a Voltmeter

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A voltmeter is i of the near useful devices for home electrical testing, when used correctly. Earlier using a voltmeter for the start time, learn how to set the device correctly, and test it out on a depression-voltage circuit such equally a household battery.

This article describes how to test for voltage. You lot may also be interested in using a multimeter to test for current and resistance.

1. ane

   Set your device to measure voltage. Virtually voltage-measuring devices are actually multimeters, which can test several aspects of electrical circuits. If your device has a knob with several settings, set it to one of the following:^[1]

   • To examination the voltage of an Air conditioning circuit, set the knob to V~, ACV, or VAC. Household circuits are almost always Alternate Electric current.
   • To examination voltage of a DC circuit, choose V–, V---, DCV, or VDC. Batteries and portable electronics are typically Directly Current.

2. 2

   Choose a range above the max expected voltage. Most voltmeters accept several options marked for voltage, and then you can modify your meter's sensitivity to get a good measurement and avoid damaging the device. If your digital device has no range option, information technology is "autoranging" and should detect the correct range itself. Otherwise, follow these guidelines:

   • Choose a setting college than the maximum expected voltage. If you take no thought what to expect, choose the highest setting to avoid damaging the device.
   • Household batteries are usually labeled with the voltage, typically 9V or beneath.
   • Automobile batteries should be at approximately 12.6V when fully charged with the engine off.^[2]
   • Household outlets are typically 240 volts in most of the world, and 120 volts in the United states and some other countries.^[three]
   • mV stands for millivolt (ⁱ/₁₀₀₀ 5), sometimes used to signal the everyman setting.

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3. 3

   Insert the test leads. Your voltmeter should come with one blackness and ane red exam leads. Each has a metal probe on one stop, and a metal jack on the other that slots into the holes in your voltmeter. Plug in the jacks as follows:^[4]

   • The black jack always plugs into the hole labeled "COM."
   • When measuring voltage, plug the cerise jack into the hole labeled V (amongst other symbols). If at that place is no V, cull the hole with the lowest number, or mA.

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1. ane

   Hold the probes safely. Practise non touch the metal probes while connecting them to a circuit. If the insulation looks worn or torn, wearable electrically insulated gloves or buy replacement leads.

   • The two metal probes should never touch each other while they are connected to a circuit, or severe sparking could upshot.

2. ii

   Touch the black test atomic number 82 to ane part of the excursion. Test circuits for voltage by attaching the leads in parallel. In other words, yous'll touch on the probes to ii points an already-closed circuit, with electric current running through it.

   • On a bombardment, touch the blackness lead to the negative terminal.
   • In a wall outlet, impact the black lead into the neutral hole, which in the US is the larger vertical hole, or the vertical hole on the left.^[v]
   • Whenever possible, allow go of the black test lead before moving on. Many black probes take a small plastic bump that can stick into an outlet.

3. 3

   Bear upon the red test pb to another betoken on the excursion. This will complete the parallel excursion and cause the meter to display the voltage.

   • On a bombardment, touch the carmine lead to the positive terminal.
   • In a wall outlet, fit the red pb into the "hot" hole – in the U.s., this is the smaller, vertical hole, which is ordinarily on the right.^[6]

4. four

   Raise the range if you get an overload reading. Immediately raise the range to a higher voltage setting if y'all get ane of the following results, before your device is damaged:

   • Your digital display reads "OL," "overload," or "1."^[vii] Notation that "1V" is a real reading, and nothing to worry well-nigh.
   • Your analog needle shoots to the other side of the scale.

5. 5

   Adjust the voltmeter if necessary. You lot may need to make adjustments if a digital voltmeter display reads 0V or null at all, or if an analog voltmeter's needle has barely moved. If there is still no reading, try the following in social club:

   • Make sure the test probes are both connected to the circuit.
   • If you lot are measuring a DC circuit and get no result, look for a small knob or switch on your device labeled DC+ and DC- and motion information technology to the other position.^[8] If your device does not take this choice, contrary the positions of the blackness and red probes.
   • Reduce the range by one setting. Echo if necessary until you get a existent reading.

6. 6

   Read the voltmeter. A digital voltmeter will clearly display the voltage on its electronic screen. An analog voltmeter is a piddling more than complicated, merely non besides tough once you learn the ropes. Continue reading for instructions.

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1. 1

   Find a voltage calibration on the needle's punch. Choose 1 that matches the setting you lot chose on your voltmeter'south knob. If there is no exact match, read from a scale that's an easy multiple of the setting.

   • For example, if your voltmeter is set to DC 10V, await for a DC calibration with a max reading of 10. If this isn't available, discover one with a max of fifty.

2. ii

   Estimate the needle's position based on nearby numbers. This is a linear scale just like a ruler.

   • For example, a needle pointing halfway betwixt 30 and 40 indicates a reading of 35V.

3. 3

   Divide your answer if using a unlike calibration. Skip this stride if you are reading from a scale that exactly matches your voltmeter'south setting. Otherwise, right for the difference past dividing the printed scale's max value by your knob setting. Split the number the needle points to by your answer to get the bodily voltage.

   • For example, if your voltmeter is set to 10V but yous are reading off a 50V calibration, calculate fifty ÷ 10 = v. If the needle is pointing at 35V, your actual outcome is 35 ÷ 5 = 7V.

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Add New Question

• Question

  Where do you place the red and black leads of a voltmeter if you lot're measuring a typical United states wall outlet?

  

  Ricardo Mitchell
  Electrician & Construction Professional, CN Coterie

  Ricardo Mitchell is the CEO of CN Coterie, a fully licensed and insured Lead EPA (Environmental Protection Bureau) Certified construction company located in Manhattan, New York. CN Coterie specializes in full home renovation, electrical, plumbing, carpentry, cabinetry, furniture restoration, Adjuration/ECB (Office of Administrative Trials and Hearings/Ecology Control Lath) violations removal, and DOB (Section of Buildings) violations removal. Ricardo has over 10 years of electrical and construction experience and his partners have over 30 years of relevant experience.

  

  Electrician & Construction Professional, CN Coterie

  Expert Reply

  On a wall outlet, you lot have a longer side and a shorter side. Put the scarlet final into the smaller pigsty, which is commonly the hot side, and the black last into the longer side.

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• The instructions for testing wall outlets presume yous are trying to notice the voltage "seen" by the appliance you plug in. If yous are trying to detect wiring problems, you may also wish to measure the voltage between the ground and one other hole. If you go a low result (say 2V), that hole is the neutral wire, and you lot've just measured the voltage drop. If you get a higher issue (say 120V or 240V), that hole is attached to the hot wire.^[ix]

• If yous're testing a wall outlet, examination the vertical prongs. If it's a 3-prong plug, the round hole is the ground and doesn't need to be tested.^[10]

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• Improper use tin destroy the device, cause a astringent electrical shock, or create electrical sparking that can start a fire. These are much more than probable to occur in a wall outlet or other loftier-voltage circuit than when testing a depression-voltage battery.

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Commodity Summary X

To use a voltmeter, set the device to measure voltage and choose the type of electric circuit you're working with. Next, select a range setting above the max expected voltage of the circuit. Then, insert the black test pb into the hole labeled "COM" and plug the cherry test lead into the hole labeled "V." Exist conscientious non to touch the metal probes when you're connecting them to the circuit! If yous get an overload reading, raise the range to a higher voltage setting and try over again. For tips on using an analog voltmeter, read on!

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Source: https://www.wikihow.com/Use-a-Voltmeter

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