Advice - steps for testing for stray voltage

[Brew12]

You may find this interesting.
https://interestingengineering.com/the-great-barrier-reef-may-be-restored-using-electricity

 

[Fish_N_A_Box]

I have to Agree with Brew on what he says, not because he lives in Alabama (So do I), but I'm also a retired electronics tech for the USCG and what he has said and the steps he walked you through are sound.

I can't see such a low amount causing harm, however that is not to say something isn't causing a spike from time to time.

 

[Makers Marc]

I believe yall. I don't think stray voltage was my issue either, just trying to eliminate all things.

I also know everything should be in a gfCI, but I have read horror stories of the outlet tripping and not being home to reset it caused a tank crash. So I just figured, if at least one powerhead is running it buys me sometime.

Either way, everyone has eased my mind and I feel comfortable eliminating that.

 

[Brew12]

I believe yall. I don't think stray voltage was my issue either, just trying to eliminate all things.

I also know everything should be in a gfCI, but I have read horror stories of the outlet tripping and not being home to reset it caused a tank crash. So I just figured, if at least one powerhead is running it buys me sometime.

Either way, everyone has eased my mind and I feel comfortable eliminating that.

I understand your concern with that. It is why I run my system on multiple GFCI's. A trip of a single GFCI will not cause a loss of flow in my tank. With my controller, I get an email alert letting me know if a GFCI does trip. My tank would be fine for a day if one does trip.

 

[Nicholas Dushynsky]

That would imply to me that your system is grounded. Do you use a ground probe?

It will be grounded through the lead on the meter as it requires a path to get the reading to earth

 

[Nicholas Dushynsky]

I would love a reading of 0.4v mine is 96v. I'm in the UK so voltage is higher here and none of my equipment is on a gfci as all our house wiring is on an RCD. I only have 6 sockets used 3 pumps a heater,light and ato even turning one off at a time the value only drops by maximum of 20v even my light that has nothing at all touching the tank puts in 4v of induced voltage as the cables loomed together and that creates a magnetic field around the cable which gets picked up.
I can put my hand in the tank while the meter is on and the voltage drops to 22v as it's taking a path through me and I stood on a plastic stool to prove it and it didn't drop it stayed at 96v. Even with just my DIY ato turned on, which are 2 floats in series 1 high level and 1 low fed off of a 9v DC power supply so my peri pump runs slightly slower puts in 24v ac read on the meter.

 

[Dom]

Thanks!

So does it matter if I use the grounded plug on the Apex eb832 outlet or my wall outlet?

Majority of things are plugged into my Apex outlet (which plugs into a wall GFCI)except one powerhead which I left in a wall (non-gfci) in case of trip

For the purpose of locating the source of stray voltage, I'd go right to the wall outlet.

 

[Brew12]

It will be grounded through the lead on the meter as it requires a path to get the reading to earth

Typically, the term "grounded" is used to indicate a low resistance connection to ground. The meter while in voltage testing mode will create a path to ground but it will have a very high impedance.

I'm in the UK so voltage is higher here and none of my equipment is on a gfci as all our house wiring is on an RCD.

An RCD (Residual Current Device) and a GFCI (Ground Fault Circuit Interrupter) are 2 names for the same thing. RCD is the preferred term in Europe but they function the same way.

 

[Nicholas Dushynsky]

Typically, the term "grounded" is used to indicate a low resistance connection to ground. The meter while in voltage testing mode will create a path to ground but it will have a very high impedance.


An RCD (Residual Current Device) and a GFCI (Ground Fault Circuit Interrupter) are 2 names for the same thing. RCD is the preferred term in Europe but they function the same way.

That's why I'm not putting a gfci on my tank as the circuit board my tank is on has one.

 

[Nicholas Dushynsky]

Is there a way of testing current in a tank?

 

[Brew12]

Is there a way of testing current in a tank?

Not that I am aware of, at least not with readily available equipment. It could be done with highly specialized magnetic sensors but these types of test sets run $100k+.

If you use a ground probe (or grounded heater) with your RCD you can be fairly confident that your total current flow in the water is less than the trip setpoint of the RCD. In the US, most GFCI's trip at 5mA but I believe RCD's in Europe are set a little higher.

 

[Nicholas Dushynsky]

Yeah its 30ma over here and just checked it's an RCCB not an RCD. Same thing

 

[Nicholas Dushynsky]

Yeah its 30ma over here and just checked it's an RCCB not an RCD. Same thing

Thing is I've worked in the switchboard manufacturing industry for nearly 23 years for universities, hospitals, windfarms and many other places that need them incorporating auto changeovers for mains and generator and deal with 24v, 30v, 115v, 230v and 415v and all the way up to 6000A but that's in enclosed metal box with no water in sight.
So I know absolute squat about how electricity is induced with AC and DC pumps in a 24x18x18 and how it gets there, even if I know I'd forget how to do certain things in my job as I can learn so much :)

 

[Brew12]

Thing is I've worked in the switchboard manufacturing industry for nearly 23 years for universities, hospitals, windfarms and many other places that need them incorporating auto changeovers for mains and generator and deal with 24v, 30v, 115v, 230v and 415v and all the way up to 6000A but that's in enclosed metal box with no water in sight.
So I know absolute squat about how electricity is induced with AC and DC pumps in a 24x18x18 and how it gets there, even if I know I'd forget how to do certain things in my job as I can learn so much :)

A true DC pump would induce very little voltage. True DC motors all have to have carbon brushes connecting the rotor to the stator. What we call DC pumps still have some form of alternating voltage. So, with that said...

Faraday's law is only actually defined as an equation. The best explanation I can give is that a conductor within a magnetic field will have a voltage induced if there is relative motion between the two. Since it is an equation, it also holds true that current flowing within a conductor will generate a magnetic field.

Salt water is a conductor. Our wires and pumps have current flowing through them which generates a magnetic field. The fact that the current isn't constant (AC) provides relative motion between the water and the magnetic fields so a voltage is induced. This also shows that more voltage will be induced if you have longer runs of cable or higher amounts of current flowing through that cable.

Does that help?

 

[Nicholas Dushynsky]

A true DC pump would induce very little voltage. True DC motors all have to have carbon brushes connecting the rotor to the stator. What we call DC pumps still have some form of alternating voltage. So, with that said...

Faraday's law is only actually defined as an equation. The best explanation I can give is that a conductor within a magnetic field will have a voltage induced if there is relative motion between the two. Since it is an equation, it also holds true that current flowing within a conductor will generate a magnetic field.

Salt water is a conductor. Our wires and pumps have current flowing through them which generates a magnetic field. The fact that the current isn't constant (AC) provides relative motion between the water and the magnetic fields so a voltage is induced. This also shows that more voltage will be induced if you have longer runs of cable or higher amounts of current flowing through that cable.

Does that help?

Yep that helps. Thank you.
I learnt all about motors at college 20 years ago that's long gone now. Plus it was 3 phase so not relevant really.

 

[Nicholas Dushynsky]

I'm thinking then I shouldn't worry too much even though I have around 96v as "stray voltage" albeit that it is infact an induced voltage and not to worry too much. I even plugged my fish tank into a gfci socket one component at a time, with a home made a earthing probe with a stainless steel spoon, bent to hook into the tank with a length of cable wrapped around the end out of the water (copper) and run to the main outlet earth to see if anything was at fault with it and it didn't trip.
I think I will worry when I get a shock and there is a current in the tank that uses me as a path or if I notice the fish acting funny. Or just keep my insulated boots on and not worry about it.
How many people actually turn everything off before getting their hands wet?

 

[Brew12]

I'm thinking then I shouldn't worry too much even though I have around 96v as "stray voltage" albeit that it is infact an induced voltage and not to worry too much. I even plugged my fish tank into a gfci socket one component at a time, with a home made a earthing probe with a stainless steel spoon, bent to hook into the tank with a length of cable wrapped around the end out of the water (copper) and run to the main outlet earth to see if anything was at fault with it and it didn't trip.
I think I will worry when I get a shock and there is a current in the tank that uses me as a path or if I notice the fish acting funny. Or just keep my insulated boots on and not worry about it.
How many people actually turn everything off before getting their hands wet?

With your RCCB you shouldn't even feel a shock. It should just trip the breaker if you have an issue. Voltage is also a peculiar thing and it means little without a reference. We normally reference voltage to ground. If you have 96V in your tank, and put your hand in it wearing insulated boots, you will become energized to 96V and it won't cause issues. I know of no reasons why 96V of induced voltage would be any better or worse than 5V of induced voltage.

Since everything of mine in the tank is on GFCI I do not turn it off prior to getting my hands wet unless I need to for the work I'm doing.

 

[Nicholas Dushynsky]

With your RCCB you shouldn't even feel a shock. It should just trip the breaker if you have an issue. Voltage is also a peculiar thing and it means little without a reference. We normally reference voltage to ground. If you have 96V in your tank, and put your hand in it wearing insulated boots, you will become energized to 96V and it won't cause issues. I know of no reasons why 96V of induced voltage would be any better or worse than 5V of induced voltage.

Since everything of mine in the tank is on GFCI I do not turn it off prior to getting my hands wet unless I need to for the work I'm doing.

I agree I only turn an item off if I'm cleaning it. I did that experiment with 1 boot on and 1 off , swapping feet the meter went from 96v down to 22v sad but I had to try it.ive been shocked with 415v a few time and with a 1000v insulation resistance tester, not the 2500v flash test I have to use on occasion though, that might sting a little more.

 

[Nicholas Dushynsky]

Double post sorry

 

[vetteguy53081]

With your RCCB you shouldn't even feel a shock. It should just trip the breaker if you have an issue. Voltage is also a peculiar thing and it means little without a reference. We normally reference voltage to ground. If you have 96V in your tank, and put your hand in it wearing insulated boots, you will become energized to 96V and it won't cause issues. I know of no reasons why 96V of induced voltage would be any better or worse than 5V of induced voltage.

Since everything of mine in the tank is on GFCI I do not turn it off prior to getting my hands wet unless I need to for the work I'm doing.

Where do you recommend ground probe be placed? ( In the tank or in the sump?) I had first time stray voltage 2 weeks ago in new system. I have the ground probe placed in center of tank and stray voltage is gone BUT it is just hanging there in center of tank.