Stray Voltages (again)

Discussion in 'General Discussions and Advice' started by jensvb, 27 Sep 2012.

  1. jensvb

    jensvb

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    Hi,

    Help? I got zapped yesterday for the first time with a little paper cut on my pinkie.

    So I found my voltmeter and measured the voltage of my tank to ground and saw 8.5volts.

    I then unplugged 1 piece of equipment at a time and saw little drops all along. I could not identify any 1 piece of equipment being responsible. In fact they all were a little bit responsible.

    So I plugged them back in 1 at a time and documented the change in voltage with each new piece of equipment (didn’t matter if it was on or not, which was interesting).

    So, how much of a stray voltage is a problem?

    Come on guys, let’s get realistic… how many of you are running “zero” volt ungrounded systems?

    Yes, I know that all systems will have some voltage (transformer theory teaches us that)

    How many of you know what your voltage flowing through your system to ground actually is?

    Yes I do know that the voltage is not actually flowing until the circuit is completed.

    How much stray voltage is too much?

    Regards
    Jens

    PS: For interest sake, here is the list of equipment and the voltages noticed when plugging in the equipment. (all equipment is plugged into1 of 3 Profilux PAB power bars)

    Bar 1 / Plug 1 CO2 solenoid = 0.4
    Bar 1 / Plug 2 Ozone generator = 0.0
    Bar 1 / Plug 3 Nitrate reactor feed pump = 1.8
    Bar 1 / Plug 4 Carbon reactor feed pump = 0.6
    Bar 1 / Plug 5 Phosphate reactor feed pump = 0.4
    Bar 1 / Plug 6 Calcium reactor feed pump = 1.4
    Bar Subtotal = 4.6

    Bar 2 / Plug 1 Uplift pump = 0.6
    Bar 2 / Plug 2 Airpump = 0.0
    Bar 2 / Plug 3 Heater 2 = 0.6
    Bar 2 / Plug 4 Skimmer Pump = 0.4
    Bar 2 / Plug 5 Heater 1 = 0.6
    Bar 2 / Plug 6 Auto topup feed pump = 0.4
    Bar Subtotal = 2.6

    Bar 3 / Plug 1 Kalk reactor circ. pump = 0.2
    Bar 3 / Plug 2 Nitrate reactor circ. pump = 0.6
    Bar 3 / Plug 3 Calcium reactor circ. pump = 0.4
    Bar 3 / Plug 4 <not connected>
    Bar 3 / Plug 5 <not connected>
    Bar 3 / Plug 6 <not connected>
    Bar Subtotal = 1.2
    Total = 8.4
    Multimeter reading = 8.5

    (just could not find a way to format the information nicely in the editor)
     
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  3. RiaanP

    RiaanP Moderator

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    Induction of the pumps and magnetic ballasts will cause some stray voltage. But more likely the cause is saltspray over you lights. When last did you clean around the lights?

    8.5 is not a lot. And any paper cut will feel it. Strangely kids feel stray voltage a lot more than adults. One way to keep their hands out of the tanks :)

    Worst I had was 132V from a heater that only switched on after I had my hands 2 minutes in the water. Suddenly.... ZAPP.... ouch
     
  4. Riaanv

    Riaanv

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    I currently have it jumping between 21 and 42, if I switch the skimmer off 9V remains. Not too sure what is acceptable, but not noticed any effect on any livestock, even when it was sitting at 240V.

    Most I had was 240V and found that out initally by touching the water. Luckily pulled hand quick/the power tripped :)

    Bought the volt meter after that and tested before I touched for a while, but got lazy since then again...but I do now stand with shoes on a 30mm piece of isoboard or a ladder when I touch the water. Cannot feel the 42V if with shoes on the board (feel it with no shoes on ground), not sure whether I would feel 240V. Hope not because it was unpleasant.
     
  5. Perky Pets

    Perky Pets Sponsor

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    Hi Jens - nice write up - i have never tested our tanks , but the 3 meter cad deliver a nasty blow at times...

    Bring the meter in sometime , lets do the tanks and see whats our norm...

    D
     
  6. RiaanP

    RiaanP Moderator

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    Get yourself a stainless steel welding rod. Remove the flux. Sand it smooth. Connect directly to 3 prong plug earth connection and plug it in. Better safe than dead....

    RIP Herkie.
     
  7. Perky Pets

    Perky Pets Sponsor

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    Yes or Vertex has a grounding probe - R189.95
     
    Last edited by a moderator: 27 Sep 2012
  8. mytank

    mytank

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    Guys can I ask you a silly question. I have volt meter, however how do I use it to test the sump? Some reason I am finding my tank stand is shocking me..... softest shock and usually on my cheek (when I am struggling to do something)
     
  9. NADEEM

    NADEEM

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    @RiaanP , what do you mean exactly? do i connect a piece or wire to the welding rod and plug earth, drop the welding rod in tank and plug in the plug? is that it?
     
    Last edited by a moderator: 26 Nov 2015
  10. RiaanP

    RiaanP Moderator

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    yeah
    Put the rod in the sump. Out of the way. Just ensure wherever you plug it it is earthed. Well, that is obvious...
     
  11. jensvb

    jensvb Thread Starter

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    Hi,

    Thanks for all the replies.

    Firstly I subscribe to the general rule of thumb to not install a grounding probe.

    The reasons are, firstly, that you are then definitely completing the circuit and the electricity will flow through the tank (as opposed to just "being there")... the flow of electricity is called amps. Amps is what kills, both fish and people (think of the bird sitting on the overhead electric cables)

    Secondly, if you install a grounding probe you will never know that you have a problem. Electricity will enter via induction or via a faulty piece of equipment and follow the path of least resistance to ground (like all electricity does).

    Thirdly, unless you install a titanium (preferred) bar or salt water "resistant" stainless steel bar as your grounding rod you will be leaching metals into your tank (through corrosion of the metal caused by electrolysis). Think about copper, most metals will be alloys and/or copper coated metals… what about the copper cables carrying the current (you have to make 110% certain that they don’t touch the salt water or salt pray)

    Fourthly, probably minor and something I haven't really read up on, but like to think I understand, you could end up with oxygen depletion in the water as a result of the oxidation.

    Maybe I am being to cautious… bordering on stupidity (I would rather be dead than have electricity flowing through my fish ?!?).

    So, my original question remains, how much stray voltage is too much?

    Regards
    Jens
     
  12. NADEEM

    NADEEM

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    cool , which colour wire is the earth again ? hahahaa
     
  13. Riaanv

    Riaanv

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    @RiaanP do you keep it plugged in or only plug it in when working in the water?

    If continously plugged in will the flow of current not affect the live stock in the long run?
     
  14. jensvb

    jensvb Thread Starter

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    Should that not read, "The circuit is only complete when the tank is grounded"?

    ;)
     
  15. jensvb

    jensvb Thread Starter

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    Hole in the head and lateral line errosion have both been linked to stray voltages in the tank

    (references on hand, that are easy to share, anyone?)
     
  16. RiaanP

    RiaanP Moderator

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    Mine is plugged in constantly.
    You can add a simple cheap voltmeter to always show what is the flow.
    But seriously, I rather have the power trip than me pushing up daisies.

    On serious note. Please do not take changes. Fellow reefer and MASA member died a couple of months ago doing maintenance on his tank. Due to stray voltage.
     
  17. jensvb

    jensvb Thread Starter

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    Connect the black probe to the earth (NOT the live or neutral, the earth) on a three prong plug (I am over cautious, so I removed the live and neutral pins so that I can't accidently touch them).

    Then drop the red probe into the sump and take your reading.

    (basically, the volt meter needs to be in "series" to ground... start with a setting capable of reading 240v and work your way down to something with more of a realistic scale... it's difficult to read 8.5v on the 240v scale... unless you go digital of course)
     
  18. jensvb

    jensvb Thread Starter

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    Hi Riaan,

    I have been thinking about doing the same.

    Have you done this?

    How long do the batteries in a volt meter last in "permanent" mode?

    Also, should one not monitor voltage and amperage?

    Therefore 2 volt meters?

    Just pondering out aloud.

    Regards
    Jens
     
  19. Gary Roebuck

    Gary Roebuck

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    just to interject.. i'm sure Riaan is referring to a 'voltmeter' n not a 'testing device'. a voltmeter uses the voltage in the system to indicate the voltage! iow.. no batteries required ..
     
  20. RiaanP

    RiaanP Moderator

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    yes.
    had one long time ago.
    Currently not one in place.

    I did bend the welding rod, giving it a small hook at the one end. so that I can hook it over the side of the sump. Use normal terminal connector block and connected a piece of wire to that. Plug got only the earth wire. No other wires coming out. Can actually do the suggestion to remove the other two pins for more safety.
     
  21. zayd

    zayd

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    I am not very clued up when it comes to this, but I have a titanium heater that is grounded via the power supply.

    1. Would this sort out any stray voltage?
    2. Would the issue mentioned by JENSVB still be of concern in terms of the flow of voltage or amps per post #10?

    Thanks
     
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