how to test for stray voltage

[jthomas0385]

I lost my Foxface a week ago, and than my dwarf angel today. I'm really getting frustrated with losing fish that seem very healthy one minute, and die the next. I tested all of my water parameters, and even went to the LFS for a second round of testing. Everything is fine with my water chemistry, even the LFS was surprised to see my nitrates and phosphates were 0 with out a ruge. They suggested to check for stray voltage, anybody know how to do this? What do I buy, how much it will cost?? Thank you.

 

[deejeff442]

since everything is pluged into a 110 wall outlet .if you stick your finger in the water you will know.
my old mh light system did that so i just put some wood under it to keep it off the tank rim .no more shock in the water.
if you feel a shock in the water then just start unplugging things one at a time.

 

[ryancw01]

You can buy one of those stray voltage grounding kits if it will give you some piece of mind. Sometimes really cheap heaters and pumps can leak out stray voltage, but if you have spent money on quality items then it really shouldnt happen normally. I tried to buy one of those grounding kits and the guy at the fish store told me not to waste my money. I still kind of want one for piece of mind though.

 

[scsinet]

You can't effectively check for stray voltage with conventional testing equipment. Many folks try to use multimeters to check, but the problem is that they are sensitive enough to read the normally occuring harmless eddy currents and give false readings.
The best policy is to operate your tank on a GFI and with a grounding probe. The GFI will trip if a grounding probe is used and a stray voltage fault exists.
Grounding probes alone without the GFI can make the problem worse. What they can cause is a condition where fault current flows continously through the water, from the point where the fault exists to the grounding probe - making the problem worse.
Generally speaking, 90% of the time that stray voltage gets blamed for a problem, it's not. Fish that are suffering from so-called "stray voltage" do not die suddenly, unless the problem is very serious (where you'd get a painful shock from putting your hand in the water).
I'd look elsewhere. A few questions... how long has the tank been operational? What are your parameters apart from what you listed? I have trouble believing that nitrates and phosphates could be zero as well. How big is the tank and what other livestock do you have? Where do you get your source water? How long did you have the fish that died?

 

[salty blues]

Originally Posted by SCSInet
http:///forum/post/3019041
The best policy is to operate your tank on a GFI and with a grounding probe. The GFI will trip if a grounding probe is used and a stray voltage fault exists.
IMO a GFCI alone is all that is really needed. It will most certainly trip under a fault condition whether a probe is used or not because of the nature that a GFCI operates, which is to sense any sudden current imbalance between the "hot" and the "neutral" conductors in the circuit. This is why GFCI's will work even on older wiring that has no "ground" in the circuit.
That being said, having a probe in conjunction with a GFCI certainly won't hurt, but every system should certainly have at least a GFCI.

 

[scsinet]

Originally Posted by salty blues
http:///forum/post/3019666
IMO a GFCI alone is all that is really needed. It will most certainly trip under a fault condition whether a probe is used or not because of the nature that a GFCI operates, which is to sense any sudden current imbalance between the "hot" and the "neutral" conductors in the circuit. This is why GFCI's will work even on older wiring that has no "ground" in the circuit.
That being said, having a probe in conjunction with a GFCI certainly won't hurt, but every system should certainly have at least a GFCI.
You're partially correct.
It's true that a GFI will work on an ungrounded system because in a fault condition, the current is finding an alternate path to ground, usually through the user of the equipment to a non electrical ground, such as bare earth, a water pipe, etc.
In the case of a GFI on a fish tank, if the water is not tied to ground, when a fault occurs, the water will sit, electrically live. However, because there is no ground path anywhere (throught the GFI or otherwise), the GFI will not trip. No current will flow because it's an incomplete circuit. When a user who is grounded elsewhere sticks his hand in the water, the circuit is complete, current flows, the user receives a shock, and the GFI will trip.... in that order.
Of course, the GFI is designed to trip before dangerous amounts of current can pass, but still... I'd rather not recieve the shock in the first place.
Now, many hobbyists will argue that this is actually a more ideal situation, becuase that way the GFI will trip when the hobbyist is right there at the tank, rather than tripping in the middle of the night or when nobody is home to power the tank back up. I suppose that's a valid point.
In the end, I guess it all comes down to what school of thought you want to subscribe to.
But at any rate, the difference in current between hot and neutral that a GFI identifies and trips over cannot occur until the current has an alternate path to ground. If the water is not grounded, no alternate path (and hence no trip) can occur until the water is grounded... which would likely be through a human...
What I always tell people is no GFI, no probe... NOT SAFE. Probe, no GFI... NOT SAFE. GFI and no probe... SAFE. GFI and probe... SAFE.

 

[maxsmart]

How bad will the shock be? I keep feeling something when I'm siphoning and a particular finger hits the water, but I can't tell if it's because I have a tiny cut on that finger and the salt is the culprit, or if I'm being shocked. It feels like electric shock, not like salt on a wound, so I'm wondering now if this is the cause of my large rate of livestock death.
What I'm feeling is like a papercut, just on the tip of the finger - not a whole-body shock, like when you grab a live 50v phone wire.
If I do have a problem, what should I do? I have three heaters, two in the sump and one in the tank, two pumps both in the sump (skimmer + return pump), and a light - that's it. The light sits on top of the glass cover, on 4 rubber feet - so that couldn't be it, right? Or could it induce voltage through the field created by the T5 bulbs?

 

[scsinet]

The exposed flesh in your wound is more suseptible to the current.
Unplug half of your equipment. If the shock stops, then plug half what you unplugged back in, etc etc. Just divide and conquer until you identify the piece of equipment that is causing the issue.

 

[maxsmart]

Originally Posted by SCSInet
http:///forum/post/3097161
The exposed flesh in your wound is more suseptible to the current.
Unplug half of your equipment. If the shock stops, then plug half what you unplugged back in, etc etc. Just divide and conquer until you identify the piece of equipment that is causing the issue.
Unplugged everything, still feels like I'm getting shocked. Going to leave the one heater in the tank (as opposed to in the fuge) unplugged to see if that does it. It's way too warm (83-86F) in the tank anyway this time of year. Would it help to test the potential between the water and the ground on my outlet? I do have a voltmeter (former EE).

 

[scsinet]

THe problem is that high impedence of DMMs means that they'll read eddy currents.
You can certainly test it, but the reading isn't going to be conclusive unless it reads zero or near zero.
If you've unplugged all equipment and are thoroughly satisfied that you have disconnected anything associated with the water and still feel like you are getting a shock, then what you are feeling is probably not a shock. I mean... the current has to come from someplace for you to get a shock, that's all there is to it.
The current can't remain in the water... the instant you disconnect something causing a problem is the instant the current will be gone. It's not "residual."

 

[windlasher]

Originally Posted by deejeff442
http:///forum/post/3018941
since everything is pluged into a 110 wall outlet .if you stick your finger in the water you will know.
my old mh light system did that so i just put some wood under it to keep it off the tank rim .no more shock in the water.
if you feel a shock in the water then just start unplugging things one at a time.
OK... WTF??? TALK ABOUT CRAP ADVICE.
IT IS NEVER OK TO TEST WITH YOUR BODY IF YOU SUSPECT ELECTRICITY IS THERE. BUY A VOLT METER. YOU CAN FIND CHEAP ONES FOR $10.

 

[lovinmynemo]

ok a voltmeter will help ,but it may not catch the milliamps thar can kill your fish,If you decide to go gfi I suggest a gfi breaker installed at the panel due to the volume of receptacles that require being reset everytime the power goes out ,so if your not home the tank sits idle until you get back good luck and hope this info helps

 

[nihoa]

hahah +1
Originally Posted by windlasher
http:///forum/post/3104148
OK... WTF??? TALK ABOUT CRAP ADVICE.
IT IS NEVER OK TO TEST WITH YOUR BODY IF YOU SUSPECT ELECTRICITY IS THERE. BUY A VOLT METER. YOU CAN FIND CHEAP ONES FOR $10.

 

[d-man]

OK... WTF??? TALK ABOUT CRAP ADVICE.
IT IS NEVER OK TO TEST WITH YOUR BODY IF YOU SUSPECT ELECTRICITY IS THERE. BUY A VOLT METER. YOU CAN FIND CHEAP ONES FOR $10.
by the time it gets into your tank it's not going to be 110 any more, I grew up on a 12 volt system and it's just fine to test with your body with lower levels of electricity.... it's best if you use your tung

 

[windlasher]

Originally Posted by d-man
http:///forum/post/3104760
OK... WTF??? TALK ABOUT CRAP ADVICE.
IT IS NEVER OK TO TEST WITH YOUR BODY IF YOU SUSPECT ELECTRICITY IS THERE. BUY A VOLT METER. YOU CAN FIND CHEAP ONES FOR $10.
by the time it gets into your tank it's not going to be 110 any more, I grew up on a 12 volt system and it's just fine to test with your body with lower levels of electricity.... it's best if you use your tung
the point is, you dont know what the voltage is. every hear of people dying from dropping hair driers or radios into the tub? SORRY... ITS A STUPID IDEA.

 

[lovinmynemo]

Originally Posted by windlasher
http:///forum/post/3105952
the point is, you dont know what the voltage is. every hear of people dying from dropping hair driers or radios into the tub? SORRY... ITS A STUPID IDEA.
Maybe his wife just took out a big insurance policy and her boyfriend is offering this advice

 

[usirchchris]

Originally Posted by windlasher
http:///forum/post/3105952
the point is, you dont know what the voltage is. every hear of people dying from dropping hair driers or radios into the tub? SORRY... ITS A STUPID IDEA.
Not here to make any other point then...I have heard of people dropping hair driers and radios, but have never met anyone who knew someone that did, or ever hear of a real life occurence. Anyone know anyone that this happened to?

 

[d-man]

Originally Posted by usirchchris
http:///forum/post/3106070
Not here to make any other point then...I have heard of people dropping hair driers and radios, but have never met anyone who knew someone that did, or ever hear of a real life occurence. Anyone know anyone that this happened to? %%
good thinking, it's a lot harder to kill your self this way than people think because there is no reason for the electricity to go through you (not that it cant happen), but my point was that by the time it gets to you tank it's probably not ac it's dc and as far as I know dc can not kill you. Your right it's not a good idea to test things you don't know about with your body.... but I'll do it... and 110 is not that bad, it just made me jump (never trust anyone but yourself when it comes to turning things off)

 

[scsinet]

Lots of misinformation flying around on this thread...
DC CAN kill you, but it's a moot point because AC can't just change to DC by passing through water... it's still AC.
Yes, using your body to test for current is not a good idea. Unfortunately, the realtity of the situation is that regardless of how much testing you do, you've gotta stick your hand into that water sooner or later. Furthermore, a digital meter is not going to give you what is necessarily a clear idea that a problem does or does not exist, so sooner or later you just have to take it on faith that it's fixed, and stick your hand in the tank.
To be clear... I'm not advocating the idea of using your body as a test instrument, I'm saying that a meter cannot tell you for sure whether you've solved the problem. It might give you good confidence, but that's it.
The problem is that digital meters have a very high input impedence. Although it sounds strange, it means the meters can detect eddy currents which may read significant voltages, but carry no current behind, so they are neither dangerous nor perceptible. It may be hard for and individual who doesn't know a lot about electrical theory, but it's true.
Ergo, a digital meter reading voltage doesn't mean there is voltage there. The good thing is that generally a meter won't read 0 volts unless there really isn't anything there.
The best way for a layperson to know for sure is to equip their tanks with a GFI and a grounding probe. A GFI will not trip for eddy currents but will for actual faults, so if the GFI holds, you have no problem.

 

[maxsmart]

Originally Posted by lovinmynemo
http:///forum/post/3106001
Maybe his wife just took out a big insurance policy and her boyfriend is offering this advice
To Everyone But SCSINet: First off, I'm a EE, as I think I mentioned - I know about how electricity works. I also mentioned that I was feeling a slight shock when touching the water, so obviously I already know that the voltage issues, if any, are manageable safety-wise, since I've already touched it many times. The question wasn't of a live 110v wire, but of small, induced voltages.
To All: Anyway, back on that topic - isn't it possible that the tank (salt water, a conductor, surrounded by glass) could be acting as a capacitor, holding a built-up charge? That's why I was thinking that if something was inducing a small charge to build up, that a grounding probe might keep it from building up. I'm just questioning whether it's the saltwater on tiny cuts on my hands, or electric shock that makes it sting to put my hand in the tank.
I do have a somewhat poor survival rate in my tank, despite seemingly perfect water quality, so the thought of an electric problem gained enough feasibility to where I started questioning it.