Using ground probes in aquariums

Discussion in 'Reef Aquarium Discussion' started by Brew12, Oct 20, 2016.

  1. jasonrusso

    jasonrusso Well-Known Member

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  2. spidercrab

    spidercrab Well-Known Member

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    ...
     
    Last edited: Oct 6, 2017
  3. jasonrusso

    jasonrusso Well-Known Member

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    I don't know what you were looking for. You ask what the consensus is, then start writing BS about how you have a 5 watt return pump so you can't possibly get electrocuted because you wear rubber shoes.

    You didn't pose a question, you just made a bunch of foolish statements.

    First off, I don't think there is such thing as a 5 watt return pump. A small power head is more than that. Second, if the pump cracks open, the running wattage has nothing to do with how much current can flow through the wiring.

    The only statement you made that made sense is that you don't know a lot about electricity.
     
  4. spidercrab

    spidercrab Well-Known Member

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    There are plenty of 5w return pumps everywhere and they are great for small 10g or less tanks. I am asking a simple question when do I need to install a GFCI/ground probe? on a 2g nano tank with no electrical components except a 3v battery powered temperature gauge? on a 5 g tank with a 5w pump and a battery powered temp guage? on a 10g tank with a 50w heater, 5w pump and 3v battery powered temp gauge? I know you like your simple one answer fits all model but thats not always the case.


     
  5. jasonrusso

    jasonrusso Well-Known Member

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    The answer is ALWAYS. You don't have any electronics in your sink but you need a Gfci on any outlet on the counter top.

    You never know when you are going to be servicing the tank and you splash water onto the wall and into the outlet. Salt water is a great conductor. The Gfci is not only for the components in the tank.
     
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  6. rock_lobster

    rock_lobster Well-Known Member R2R Supporter

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    Is the ground probe needed as well in that example?
     
  7. jasonrusso

    jasonrusso Well-Known Member

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    I feel it is necessary. They cost $13. I had some sudden mysterious deaths. Maybe it was because of a shorted circulator that tripped my GFI instantly after the probe was installed. I had no idea before.

    Rio RV2735 Rid-Volt Titanium Grounding Probe https://www.amazon.com/dp/B0002DGSWE/ref=cm_sw_r_cp_apa_f9d2zb3V8HKQN
     
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  8. Brew12

    Brew12 Electrical Gru R2R Supporter R2R Excellence Award Reef Squad Build Thread Contributor Article Contributor Partner Member 2018

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    I would never run a saltwater tank without the combination of the two. Immediate fatalities from 120VAC are rare. It takes a very unlikely combination of conditions to get enough current through the heart to cause near instant death. More common would be for someone to think they are fine after a shock but suffer heart related conditions up to 48 hours later. When this results in a fatality, the source of the shock is often unknown and is characterized as a heart defect. This is why most employers require anyone who has been shocked to get an EKG.

    Most fatalities from 120VAC are due to secondary events tied to the shock such as falling off a ladder. I read about one particularly nasty event where a guy was using an electric chain saw without a GFCI. When he started to be shocked and clenched up it pulled the chainsaw into his leg. Now, we are rarely working on our tanks at elevation or with potentially dangerous tools but there are more than a few cases of R2R members who have needed stitches as a result of the reaction to getting shocked.

    The size of the equipment doesn't really come into play. If the hot conductor is exposed to the salt water it only needs to be able to conduct 0.05 amps to cause a painful shock. Even a tiny wire can conduct at least a few amps for a short period of time.

    If you have read my posts on here you will see that I don't believe fish get "shocked" in the same way people do because the seawater around them is more conductive than they are. I do believe the voltage field around them can cause HLLE or other issues. My biggest concern is that if I am leaking voltage into my system I am also likely leaking copper from the wire into the system. Copper will corrode very quickly in saltwater if current is running through it. If the fault is generating heat it is likely leaching toxins from the plastic into the water. If it is a motor, potentially toxic heavy metals may be being released into the water from the magnets and motor windings. I want to catch this as quickly as possible which a GFCI/ground probe combination can do.
     
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  9. Forsaken77

    Forsaken77 Well-Known Member

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    Basically almost all of the electrical gear, except power heads, are in the sump. If you place the grounding probe in the return chamber then the probe will most likely be the shortest path of resistance for the electricity to travel. I'm not an electrician, but as a lead cable technician, that's what they always taught us with grounding from the street and the house.
     
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  10. Brew12

    Brew12 Electrical Gru R2R Supporter R2R Excellence Award Reef Squad Build Thread Contributor Article Contributor Partner Member 2018

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    I would seriously doubt that the interference on your Apex is coming from the aquarium water. I would check for a few other things before going the water route. I have seen Apex pH probes show "noise" from other, non related modules being dirty or developing salt creep. You can also get noise by having the Apex wiring, either to the probes or other modules, being bundled together with other power cords. This is made worse if the cables go to DC pumps.

    I'm glad that you understand the importance of surface area when it comes to high frequency grounding! You have a much better understanding than most! I do need to point out that it does work a little different in a salt water aquarium. Normally we use shielded cables with either mesh or foil to provide surface area which then goes to a drain which we connect to ground. In our tanks it is the salt water that acts like the foil and the ground probe is just a convenient drain point. With the low current densities involved even a very small ground probe will make an adequate drain for almost all frequencies.

    I love experimenting myself so have fun with this!
    Just keep in mind that there are no true hobbyist level DC motors. A DC motor MUST have an electrical connection to the rotor. If you can pull the rotor on the pump then it is an AC motor. The controllers on the DC pumps convert the 120V, 60hz, AC from our outlet into DC. It then converts it back to some form of AC. This AC is typically PWM or a modified sine wave. To get a good idea of what is going on you will see it best with an oscilloscope. At the very least you will need a voltmeter that reads "True RMS" and not one of the cheaper ones that calculates RMS based on peaks.
     
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