MultiMeter Help!

Discussion in 'General Reef Topics' started by ccscscpc, Apr 3, 2010.

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  1. ccscscpc

    ccscscpc Millepora

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    Does anyone know how to use one of these?

    I just picked one up and have no clue as to what setting to put it on and what colors do I stick in the water to try to find stray voltage?

    Thanks for the help!
     

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  3. blackraven1425

    blackraven1425 Giant Squid

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    Turn it to DCV10 and stick the black probe into the water. If the needle moves, you have stray voltage. DCA 500u means you have stray current.

    The difference is not really noteworthy if you're just looking for stray electricity. I'm not sure offhand which one would be more sensitive, so check both out.
     
  4. gabbagabbawill

    gabbagabbawill Pajama Cardinal

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    You are actually looking for voltage, not a current measurement.

    DCV is DC Volts... you won't have any DC volts unless your powerheads run on the much more expensive controllable DC servo motors, which they most likely don't, and if so, you probably won't find any DC current in your tank.

    ACV is AC volts. Most powerheads, pumps, heaters, and lights use AC voltage. This is what is most likely to show up in your tank, and what you want to measure. I will tell you how to do this.

    Set the meter to ACV 250. Put the ground probe (black) on an electrically grounded outlet's ground terminal. Place the positive lead's probe (red) in the water. Use the meter's 250V scale to determine if there is any detectable voltage. This scale goes from 0-250V. If you find voltage, and it is less than 10V, you can set the meter to ACV 10 and use a higher resolution scale, which goes from 0-10V.

    If you find detectable voltage (unless you have a ground plug, you will likely find some), start unplugging equipment until it goes away, using a process of elimination to find the pieces of equipment that leak the most voltage.

    I could explain current vs. voltage, and how to measure each but that is another post entirely, and has nothing to do with what you really want to know about your tank and equipment. The ohm meter can also prove to be useful, but that is another post as well... I'm just trying to get you started on measuring stray voltage accurately.

    Hope this helps!!! If you need any further explanation or help, I'm subscribing to this thread, so please let me know... this is my expertise!
     
    Last edited: Apr 3, 2010
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  5. blackraven1425

    blackraven1425 Giant Squid

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    Very good point about AC/DC, that kinda skipped me. It really doesn't matter if you find current or voltage, though; both are going to be there if some equipment needs to be grounded.
     
  6. gabbagabbawill

    gabbagabbawill Pajama Cardinal

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    Ok, just a brief explanation... Current and voltage exist together, you can't have one without the other. Think of it like water flowing through a pipe, where voltage is the pressure of the water, and current is the speed in which it flows.

    To measure current flow of electricity, you have to put the meter in the direct path of the current flow, which is not easy to do in this case. I would say for practical reasons, you will not ever measure current in aquarium water, and it has no bearing on anything. In fact, if you were to use the meter to measure current between tank water and an electrical ground connection, the meter would act like a ground probe and you would measure zero detectable current.

    However, voltage is easily measured and is what you're looking for. ;)
     
    Last edited: Apr 3, 2010
  7. wiigelec

    wiigelec Fire Shrimp

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    Using the method gabbagabbawill has outlined I would first practice on a working outlet to make sure you get a reading of 120V, just to make sure you are using the meter correctly and that it is indeed working correctly.
     
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  9. gabbagabbawill

    gabbagabbawill Pajama Cardinal

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    Not a bad idea. ;) To do this, set your meter to 250 ACV. Stick the black probe on the ground terminal and the red lead on the hot terminal (small blade). You should see ~110-120 VAC and know your method and meter are working properly.
     
    Last edited: Apr 3, 2010
  10. ccscscpc

    ccscscpc Millepora

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    Wow....awesome explanation!

    So do I take the black and put it in the bottom hole of a 3 pronged outlet? and then place the red in the water?

    You kinda lost me when you said to ...."Put the ground probe (black) on an electrically grounded outlet's ground terminal." Will it work to place it in that bottom hole on the outlet?

    I did the first test on the DC current and got nothing....the meter didnt even budge!

    How do I test a live outlet too?

    Thanks for all the help.
     
  11. gabbagabbawill

    gabbagabbawill Pajama Cardinal

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    [​IMG]


    This might help. 'Earth' and 'Ground' are used to mean the same thing.

    This ground plug should be connected to the ground on your electrical panel, which should be connected to your cold water pipe and to a grounded rod outside of your house (hence the term Earth). Kind of convenient that you'd have a direct electrical connection to the ground outside your home, huh? Just think, with a ground probe your fish can enjoy the same electrical connection to ground as all of the fish in the ocean! ;D
     
    Last edited: Apr 3, 2010
  12. gabbagabbawill

    gabbagabbawill Pajama Cardinal

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    yep.
    sorry, I was being over-explanatory. yes, the ground is the bottom hole.
    not surprising
    as mentioned above. Also, check to see if your meter takes a battery... it may need a 9V battery (for the ohmmeter) as well as a AA 1.5V battery (for the voltmeter) to work.
    glad to!