Stray Voltage Question

[Stones]

Just out of curiousity, I tested the AC voltage in my tank today and to my suprise it measured at 25 V!!!

I've read through all of the threads on stray voltage on Canreef, as well as many articles on it as well but I'm not exactly sure what to do.

I unplugged all of my equipment and the voltage dropped to zero. It seems that not one single piece of equipment is causing the problem but rather nearly everything electrical is contributing somewhat to the total voltage. The main culprits are my JBJ top off at 4.6 V, a maxi-jet at 17.3 volts (now destined for garbage can), and a mag 18 at 5V (although my other mag 18 tests only at 0.3V???). I know that 25V is far beyond what is acceptable in a reef aquarium and I am worried that some of my fish could develop HLLE as a result. So far none of the inhabitants show any symptons athough my tomini tang has been unusually skiddish lately.

Does anyone know of any options to resolve my problem. I've done lots of reading on grounding probes and although some swear by them, there are a decent number of articles that condone their use and state that grounding probes only provide a means for the electricity to exit the aquarium so voltages will read low, but there will be a constant current passing through the aquarium which will still generate problems.

Currently, the electricity for the tank is provided by 2 grounded extension cords that are not plugged into GFI sockets, due to being in my basement (rental townhouse).

If anyone has any info to help, it would be greatly appreciated. Thanks

[untamed]

For starters...get GFI extension cords.

[BC564]

Just go to the home depot or rona and get a GFCI receptacle and replace the duplex receptacle that is there now.......they are apprrox. $10-$15.....$20 tops

[Stones]

Thanks for the info guys.

I've got the sump reading 1.9-3.6V now which is alot more reasonable than the orginal 25V. Took out the maxijet and replaced the heater with my spare, and also plugged it into a seperate outlet.

Still going to pick up some GFI outlets or powerbars just to be on the safe side though. Definately going to go with all external pumps on my next setup.

I'm just curious though as to how many people actually get a zero voltage reading in their tanks. It seems impossible to me due to the voltage that would be generated just by moving the salt water via pumps, as well as the frictional voltage generated by the salt water moving inside pvc conduits.

[banditpowdercoat]

Thing is, its not the items "leaking" voltage into the water, its more Inducing. See, Electyricity can be transmitted without contact. Electricity flowing through a conductor creates a magnetic field. A magnetic field that moves near a conductor will Induce electricity in said conductor. Its how most all AC motors work. Now, we all know that SW is very conductive. I would bet you'll see electricity in the worlds oceans too. because the world is one HUGE magnet, and the oceans flow through this magnetic field.

Now, as far as shocking you, the induced voltage is only in the water, and thus referenced to the water. it shouldnt shock you. This os not to say you cant get shocked, because if a piece of equip IS malfunctioning, then its possible. See, the electricity in your Wall is referenced to earth. meaning, the ground pin, AND the Neutral are tied to a point that contacts the ground. This means that anywhere the HOT will have potential to ground. We stand on the ground, so therefore usually are at Ground potential.

How did you measure the voltage in your tank? was it from water TO ground? or did you just plop both meter leads into the water? Water to ground=BAD
water to water=ok

[mark]

I'm wondering if the numbers really mean anything. Not saying there isn't leakage or induced voltage but leakage measurements require specialized equipment. Then there's the current, you might get a voltage but if no juice is flowing.

That's not to say skip the $20 GFI investment.

[BC564]

The GFCI is just to save from electrical shock...being it fish or him....if there is truly a voltage leak...the GFCI's will trip and he will need to find the source or equipment that is at fault...induced voltage is something all on its own

[Stones]

Banditpowdercoat, I was testing the water using one lead in the water and one lead in my ground, as I had read in several articles that this was the means of testing your water to see if you have stray voltage. These were the readings that now register at 1.9-3.6V.

When testing the water with both leads in the water, I get a voltage of 0V.

Which way is the correct way to test, as you stated that water to ground is bad?

[banditpowdercoat]

OK, ya, your checking correctly. Water to ground. Getting a few volts to ground, even 25 is not bad. There will be no amperage there. its the amperage that hurts. Also, since the fish are never touching the water and ground, there should be no harm to them. they will experience the 0V like when you put both leads in the water. Alot of times at my work, I'll get a reading of like 90+volts on a wire that is in fact de-energized. Touch the wire, nothing. Most Digital meters have such high internal resistance that they do not draw any current. this can in fact lead to erroneous readings alot of times.

but still, By all means, a GFCI is the best insurance. If there is an electrical problem, say a heater case breaks and now the live wire is in contact with the water. Everything will be good untill you touch the water and something grounded, then OUCH. GFCI will trip before you feel it.

[Stones]

Thanks again guys for all the help, as soon as I get the GFI installed I'll feel alot safer and now that I got the voltage down to less than 5V, I'm sure my inhabitants should be perfectly fine as the majority of this voltage is probably caused via induction or through static charging.

[untamed]

Can you post the settings you used on the voltmeter to get this reading? I'm curious...have a voltmeter...but am unsure on how to set it to get a proper reading.

[Stones]

No problem. I used a standard mastercraft voltmeter set to the 200V AC setting. On my meter it looks like this:
~
V

If your meter has a lower setting, you could probably use that to get better resolution but as it is, it gave me an accuracy down to one decimal place(pending the voltmeter is actually calibrated correctly)

I put the probe from the V/Ohms/mA port and placed that in the water running through my sump, and placed the ground probe in the ground socket of my powerbar that my skimmer pump runs on.

After leaving the probes in the water for a while, the voltage would fluctuate from 1.9 V up to 3.6V depending upon what electrical appliances were running at the time.

Hope this helps

[Stones]

Untamed, did you get a voltage reading from your tank yet? Just curious to see what other peoples systems are running at.

[untamed]

OK...my voltmeter seems similar to yours. Set the way you describe, I get a reading of 0.4

The reading doesn't change if I remove the ground probe that I have.

[kwirky]

For starters...get GFI extension cords.

GFI extension cords? What does one of these things look like and where do you get one?

[midgetwaiter]

You can get a 4 outlet Noma GFI powerbar at Canadian tire for just over $20. You can also get plug in ones with single outlets you can then plug a power bar or something into. We started stocking them at work recently, they're a bit cheaper and pretty decent.