Stray Voltage help

[Pete_the_Puma]

Hi there,


So last night I was doing some testing on my water. When I placed my hand in the tank I felt tingling on one of my fingers.

I immediately unplugged (or rather switched off through the Neptune) a number of devices and started testing again, using my fingers as the reference.

I ended up blaming one of my two heaters and removing it.

Problem is about 15 minutes later with that heater out of the picture I felt the tingling again. Then I noticed it was always on the same finger and that I had a small cut there. At no time did I feel tingling on any other digit despite having a bunch of them in the water at different times.

So I started thinking this was just saltwater getting into a small wound and not actual loose voltage in the tank.

But now that I think about it some more maybe it WAS a low level of stray voltage and the only place I could feel it was where my insulation (skin) was broken.


The whole tank equipment is on a GFCI cord, it never tripped. All inhabitants look great.

So I decided I want to measure the voltage in my tank, my two questions are:


1. I am assuming I need to measure voltage between tank and ground, how do I do that? I cant just stick the voltmeter wire in the tank what would it "compare" to? Or is there a way to measure with just the tank?


2. I know all pumps create/induce low level voltages in the tank, at what level would you guys be worried? I'm imagining anything below 5-10ish volts would be tolerable.


Any advice is welcome,



Pete

 

[liverock]

You have stray AC <alternating current> voltage in your tank ...use a voltmeter, set on AC voltage as low a scale as it has...put one probe in the tank water...and the other to the GROUND side of an outlet....( the little round hole under the two prong holes for the plug..and you will see some readout there....

 

[AZRippster]

If you do have stray voltage, find the culprit and fix the situation, do not install a grounding probe.

 

[Pete_the_Puma]

Would any level of measured voltage above zero be abnormal?

 

[Pete_the_Puma]

Good Read by the way AZRippster.

My first step is confirming I have a problem. I will measure the potantial difference between tank and ground.

P

 

[liverock]

Would any level of measured voltage above zero be abnormal?

yes

 

[Pete_the_Puma]

yes

So I tested my tank today...

I have 28-29 Volts of potential current. The thing is it was not a single device but rather a summation with everything adding a few volts here and there. This is all fairly new (3 months) equipment and none of it is "cheap"


Maxspect Gyre XF130
Maxspect Gyre XF150
2x Cobalt Neotherm heaters
Ecotech Vectra L1 DC pump
2 eheim small pumps for the zeovit and carbon reactors.

The one thing that surprised me (and had me questioning my measurement method) was that even the auto top off (Tunze osmolator) slightly raised the stray voltage but it had no significant direct connection with the main tank.

I measured by plugging one end of the voltmeter to the ground on the main outlet for the tank and having the other end in the water itself.

Now if you watch this youtube video you will see this seems to be fairly normal:

https://www.youtube.com/watch?v=ffDctOPRS6c

So I am assuming that if you actually measured you would ALL have some stray voltage in the tank unless you are running all external elements (closed loop with external pump, external return pump, no internal heater and Vortechs for movement)


The real question is will this potential voltage ever cause problems? If there is no grounding probe then there is really no current just a potential.


Let me know your thoughts,


Pete

 

[liverock]

There should be no current in your tank...use the meter again...unplug everything...and plug back in one at a time watching the meter...then you will find the source..

 

[BeanAnimal]

Liverock -

I think you are somewhat confusing voltage and current. It is normal to detect "voltage" in an aquarium, depending on the method of measurement and equipment used. Furthermore, that voltage measurment, be it 10v or 100v is meaningless without considering the available current that is driving it.

Voltage/Current in the aquarium can be the result of a faulty insulator on a device but it can also be induced by a device. The former is dangerous (and the reason that GFCIs are so important). There is a potential (no pun) for high current because this is a mains voltage leak. The latter (induced) is not likely dangerous but detectable via meter or a cut finger. There is simply no way to induce a high enough current to be dangerous.

 

[Pete_the_Puma]

Thank BeanAnimal,

So would you consider 25-30 V of potential normal?

I wish everyone measured their tanks and posted the results so I know if this is an outlier or somewhat normal value.


Pete

 

[Pete_the_Puma]

There should be no current in your tank...use the meter again...unplug everything...and plug back in one at a time watching the meter...then you will find the source..

I did unplug everything, and replugging devices one by one found about 2-6 volts from EACH totaling about 27 volts when everything is on.


Pete

 

[mgraf]

I am a bit confused by this as well. I have the same effect when sticking my hand I'm my tank as well, if any cuts or sensitive spots, I feel the current. I have removed heaters, pumps, etc but can never isolate the problem. I do have a grounding probe in the tank now. (Which I'm going to remove after I post this). I will be checking in to this more tomorrow.

 

[WhiteTang]

So I tested my tank today...

I have 28-29 Volts of potential current. The thing is it was not a single device but rather a summation with everything adding a few volts here and there. This is all fairly new (3 months) equipment and none of it is "cheap"


Maxspect Gyre XF130
Maxspect Gyre XF150
2x Cobalt Neotherm heaters
Ecotech Vectra L1 DC pump
2 eheim small pumps for the zeovit and carbon reactors.

The one thing that surprised me (and had me questioning my measurement method) was that even the auto top off (Tunze osmolator) slightly raised the stray voltage but it had no significant direct connection with the main tank.

I measured by plugging one end of the voltmeter to the ground on the main outlet for the tank and having the other end in the water itself.

Now if you watch this youtube video you will see this seems to be fairly normal:

https://www.youtube.com/watch?v=ffDctOPRS6c

So I am assuming that if you actually measured you would ALL have some stray voltage in the tank unless you are running all external elements (closed loop with external pump, external return pump, no internal heater and Vortechs for movement)


The real question is will this potential voltage ever cause problems? If there is no grounding probe then there is really no current just a potential.


Let me know your thoughts,


Pete

Hi!

Regarding the cobalt heaters....
I had two failing within 2 months. Both brand new!
The first one stopped working altogether.
The second burned out yesterday.
I came back home and the whole house was smelling bad! I mean really bad. That was totally strange because the same day the cleaning lady was here and the house smells great after she is finished.

I opens all my windows but the smell would linger.
After passing by the aquarium a couple times I realsed that the smell was coming from there.

Instictevly I checked the temp and it was 20 degrees Celsius.
I smelled the heater and I almost fainted.

What I am saying is check if it is the heaters! I don't trust cobalt at all.
Thank his I didn't lose any live stock and I had my trusty Eihem heater on hand

Never again a Cobalt for me!!

 

[Chibils]

If you do have stray voltage, find the culprit and fix the situation, do not install a grounding probe.

Thank you! As someone who has a very poor understanding of electricity, this settles the whole grounding probe debate for me. Is there any way to know if there's some stray current in a tank without sticking a finger in it and praying?

 

[liverock]

Thank you! As someone who has a very poor understanding of electricity, this settles the whole grounding probe debate for me. Is there any way to know if there's some stray current in a tank without sticking a finger in it and praying?

With a voltmeter....one probe in the tank water ...the other to ground...on the wall plug...

 

[Chibils]

With a voltmeter....one probe in the tank water ...the other to ground...on the wall plug...

Thanks Richard!

 

[outssider]

Thank you! As someone who has a very poor understanding of electricity, this settles the whole grounding probe debate for me. Is there any way to know if there's some stray current in a tank without sticking a finger in it and praying?

sticking your finger in is a bad... bad idea !! it doesn't take much to start your heart into an arrhythmia. That's the whole point to a gfci ...

although if you must stick your finger in, praying would help you score a few points with god before he takes you....

 

[liverock]

sticking your finger in is a bad... bad idea !! it doesn't take much to start your heart into an arrhythmia. That's the whole point to a gfci ...

although if you must stick your finger in, praying would help you score a few points with god before he takes you....

^ sound advice!

 

[jml1149]

If you do have stray voltage, find the culprit and fix the situation, do not install a grounding probe.

I would install the grounding probe. Any AC device present in the aquarium will generate stray voltage, its the nature of the beast. It doesn't need to be one faulty device, like you said, it could be the sum of several.

Also, it's a key safety precaution. If something in your system were to short, in your tank, your tank is now sitting at the same potential as your wall power. The next time you stick your hand in you're going to feel more than just a tingle.

 

[jml1149]

sticking your finger in is a bad... bad idea !! it doesn't take much to start your heart into an arrhythmia. That's the whole point to a gfci ...

although if you must stick your finger in, praying would help you score a few points with god before he takes you....

If there's no ground probe in the tank, the GFCI may not trip.

A GFCI works my measuring the hot current leaving the wall outlet and the neutral current returning to it. If the GFCI senses it's sending out more current than the neutral is returning, it assumes there's a fault and opens the plug.

But that fault current needs somewhere to go, ideally it routes through the ground probe and into the ground prong on your wall outlet.