Fish Electricution..Possible?

[JENnKerry]

I found a live current running through my QT two days ago. Which basically was 4 days too late because my Watchman Goby, Yellow Tang and Flame Angel were killed due to a faulty heater that sent electricity through the water.

I only found the problem when I stuck my hand in the tank and got shocked.
I called Marineland and they SAID they have never had a problem like this. They also stated that FISH CANNOT BE ELECTRICUTED.

Is that so?? I think they can be...thats the only explanation for my fish deaths. My clown and damsel are the only two surivors. They acted strange until I unplugged the heater..then they acted normal.

I sent the faulty heater back to them to do tests. I lost $100 in fish because of this!

But...can fish be electricuted??????

So you guys know, it was a NEPTUNE by Marineland...a 100 watt heater

[Gary Majchrzak]

IME, stray voltage can and will affect { cetain sensitive} fish. I'm not saying fish can be electrocuted. I'm saying that stray current can stress certain fish and lead to their early demise.

[saltshop]

Only if they become grounded somehow. As mentioned, the stray current is probably not particularly good for their health though.

[JENnKerry]

Not sure what fish are concidered "sensitive" but our clown has been acting strange today. I cant believe that this happened. And I know that they arent going to assume any responsibilty for what happened. Even for the shock that I recieved.

[Gary Majchrzak]

Last Autumn I lost several fish when a powerhead in my main aquarium started leaking stray voltage. I witnessed many of my long time fishes acting very strangely over the course of several weeks. My Copperband Butterflyfish and Singapore Angelfish were among the first to go. I also lost two Clownfish. When my Orange Shoulder Tang started acting bizarre and looking terrible, I went on an all out search to find the cause. Unfortunately, I found the bad powerhead too late to save the fishes already mentioned- but I saved the rest from an early death. All but my hardiest fishes {Damsels, etc.} appeared very "stressed". As soon as the offending PH was removed, every fish recovered.

[skippy2]

I also lost fish due to a faulty ph. 2 damnsels and a green brittlestar. Woke up to them dead on the bottom of the tank on xmas morning in '03.

[Gerard Alba]

Very good question...
But if a heater blows or breaks in the water, doesent it kill all fish in a matter of seconds to minutes? (and not weeks) (I sure dont know).

[JENnKerry]

Im not sure. Maybe it was only posing a threat when it would turn on. My Damsel seemed very stressed as well as the Clown. They were constantly iching their faces on the glass. I knew it couldnt be ick because they had been in QT with Hypo for almost 4 weeks at that time.
As soon as I unplugged it, they stopped iching. My clown has been acting strange since and I dont think he is going to make it. Too much stress Im guessing.
Its sad because he is at the bottom of the tank and my Damsel is right next to him, seems to be comforting the clown in some way.
He is rubbing bodies and tails with him.
Its weird, I never witnessed freshwater fish show any compassion towards an injured tank mate.
At least I was able to send the heater back to Marineland...maybe they will show compassion on my and my fish behalf and compansate me some way....YEA, long shot.

[reefeater]

The fish don't actually get electrocuted, but just as your hand felt the affects of the stray current so do the fish, only on a larger and more extreme scale, as you can imagine. I recommend getting a ground probe for your tank.

[BIGBOB]

Fish MOST CERTAINLY can be electrocuted. They must be in reference to a ground, however, meaning that for them to be electrocuted, they must fall in between the path of the current's source, and a reference to ground. For example, say you were in a pool, and suddenly a heater busted, spewing stray voltage. You would not be electrocuted until you touched the bottom of the pool, or tried to get out. You now are acting as a passage for the electricity to ground itself. (or, you are acting as the lightning rod!). Electricity is always looking for the fastest path to ground, and when you act as a connection between the electric pool, and an outside object, the electricity will travel through you. If your heater in the tank broke, than it too is spewing stray electricity, a very powerful dosage too. When your fish touches some reference to ground it too will be electrocuted. I would always use a titanium heater, which do not break like glass, as they are metal (and of course are completely noncorrosive). I bought a 300 watt one at my lfs for $20. Cheaper than many of the glass ones! A grounding probe is a good idea too, provided it is plugged into a GFI. You should run all your equipment off of a GFI protected receptacle. At any hardware, they sell portable ones, that just plug into a standard outlet, and provide another outlet that is GFI protected. This way, when equipment breaks, the ground probe sends all the stray voltage back to the GFI, and it instantly trips, cutting off power to the entire tank.

[Zephrant]

Bob- Good points, but one clarification- The fish does not have to "touch" a ground.

Consider an airplane- They get hit by lightning once in a while. They certainly conduct when they are a long way from "ground".

The point is if a fish's body is more conductive than the water around it, current will take the path of least resistance, i.e. though the fish.

You are correct that they have to roughly be between the current source and a ground though.

I also use the Titanium heaters. I use my old glass ones for mixing up new water-Just broke one last week. Luckily I had unplugged it earlier. I'll be getting a titanium one for mixing soon, and tossing all my remaining glass ones.

Zeph

[DennisRB]

What a load of BS. Anything with a nervous system can die of electrocution, and you don't need to touch ground to get electrocuted.

[reefeater]

Ok. Let's sort things out here. The pool analogy is incorrect. First off the pool equipment is grounded, so any stray voltage will go to ground, touching the bottom of the pool will have no effect, the only way you can get electrocuted is when you get out and touch either the ground surrounding the pool or a metal ladder, and complete the path to ground. The airplane in the analogy is not grounded as well. If it were grounded then when an airplane is struck by lightning all of the occupants in the airplane would be electrocuted as well. When lightning strikes an aircraft, the aircraft is inundated with an extremely large ammount of voltage for a brief moment, but since there is no complete path to ground the voltage is bled off by the aircraft skin. A GFCI will not always trip if you have a faulty piece of equipment submerged in the tank. The stray voltage has a return path to ground through the water. The GFCI will NOT trip if you have just the grounding probe plugged into it, because a GFCI measures the difference in the current going out on the black/hot wire and coming back on the neutral/white wire. The best way to alleviate stray voltage in an aquarium is a grounding probe, and ensure it is plugged into a three prong grounded recept. or GFCI. I firmly believe in using GFCI's on aquariums, but you have to realize it is not there to protect the fish, it is there to protect you.

[reefeater]

This reply is not meant to belittle anyone, just as information to everyone who reads this thread.

[reefeater]

Dennis, how can a bird sit on a 34,000 volt power line and not get electrocuted? They have a nervous system. YOU HAVE TO BE GROUNDED TO COMPLETE THE PATH OF CURRENT FLOW. ELECT 101.

[JENnKerry]

So, wouldnt the fish have been grounded if they touched their faces on the glass or a decoration in the tank?
You know how fish act when they have ick? Especially when its bad? They are jittery and scratch themselves on whatever they can find.
Thats what was happening in my QT.
My Damsel was jolting all over the place so whether they are grounded or not...there was still a current running through that tank and the fish were effected in some form.
A friend mentioned the lateral line that fish have and that it uses a form of electricity to find food or something like that.
And that if there is a stray current that it will stress the fish and cause problems...aka...death.
Shouldnt these companies go the extra length to make sure that crap like this doesnt happen?

[BIGBOB]

The lateral line is a very important sensory organ of the fish, and stray current is believed to agitate it, and lead to Head and lateral line erosion (HLLE). From here, loss of skin around the lateral line exposes the fish to secondary infections. In order for the fish to be grounded, it must be in contact with something conductive. Glass is non-conductive, and rock is generally non-conductive as well, meaning electricity won't travel through it.

[DennisRB]

"Dennis, how can a bird sit on a 34,000 volt power line and not get electrocuted? They have a nervous system."

Oh gawd. The current takes the least path path of resistance which is through the wire and not the bird. It is true that if the bird touched the ground it would die. But that does not mean you MUST touch the ground to die. If their was a gap in the wire and the bird touched either end it would also die without touching the ground. That is not a likely scenario, but electrically the same thing can easily happen to you at home, and to your fish.

BTW the only reason WHY you get electrocuted by the ground is because the power distribution system is purposely made that way. The center tap of the distribution transformers is connected to earth. If they diddn't do this you would never get electrocuted by touching earth and an active together.. The ground acts like a neutral.

YOU HAVE TO BE GROUNDED TO COMPLETE THE PATH OF CURRENT FLOW. ELECT 101."

Sorry this assumption is 100% wrong. Every one please note that you can still die of electrocution with out being grounded. People will start killing themselves if the believe that.

I am an electrician and I know what I am talking about.

If you think you can't get electrocuted with out being grounded, why don't you get some rubber boots and stand on an electricians insulating rubber mat then grab on the active with one hand and the neutral with the other. You will be dead and the GFCI won't even trip. The current will run through you body from the active and the neutral and almost nothing will run to earth. The GFCI won't measure a current differential in the active and neutral. Your body will appear as nothing more than a normal electrical load like a light bulb.

Thats what can happen to your fish in your tank. The current flows from the active through the water AND your fish and back though the neutral. Your tank justs acts as another load on the circuit. Nothing in the tank has to be grounded. In fact, if you did ground it, the GFCI should trip and nothing would get electrocuted in the first place. (as long as the fault current is big enough to set of the GFCI) Here in Australia the minimum current they can be set at is 30ma. If you had a 25ma fault current going through your tank it won't trip. But I reckon that 25ma would kill the fish eventually.

Pools: In Australia grounding yourself wont do anything electrical in a pool situation if the wiring rules have been adhered to and all the equipment is OK. Any circuit going to pool lighting needs to be run of a low voltage isolation transformer. This puts the current above earth so even if you grab on to an active while swimming in the pool, no current will flow through you (unless the isolation transformer shorts its windings out) However if a problem occurs with the underwater lights the current can flow from one light through the water and back through an another active light. If these lights are at either rend of the pool there will be a current flow through the pool and anyone in it will be getting slightly electrocuted (low voltage remember) They might not even know it, but after some time the might get paralysis and not be able to leave the pool and their condition can worsting until the die. This had happened before. Now the rules state that lights on opposing sides of a pool need to be fed from their own transformer. In the event of light failure current cant flow across the pool, therefore dramatically reducing the risk of gradual electrocution.

I hope this clears a few things up.

[DennisRB]

"The airplane in the analogy is not grounded as well. If it were grounded then when an airplane is struck by lightning all of the occupants in the airplane would be electrocuted as well. When lightning strikes an aircraft, the aircraft is inundated with an extremely large ammount of voltage for a brief moment, but since there is no complete path to ground the voltage is bled off by the aircraft skin. "

As I have shown grounding has nothing to do with it. The plane gets blasted with current while it is in the air. You don't get electrocuted because the plane has a metal skin that acts like a Faraday cage and it directs the current away from where the passengers are. (planes can and do get burn holes in them from lightning when they are in the air.) The plane situation is like the car situation. You are generally (but not always) safe in a car when it gets hit by lightning. The cars metal body acts like a Faraday cage directing the current away from you because the metal body is the path of least resistance. Insulating rubber tires have nothing to do with it. The air is a extremely good insulator. If the voltage of lightning is so huge that it can break down the insulation of 1000metes of air what hope do tires have. The tires actually conduct better than air.

[Reef Dude 29]

I have had problems with stray voltage myself, i lost a Mimic Tang. Domino Damsel, and a Clarkii Clownfish. I got a grounder for my tank and i havent had any more problems.

[reefeater]

If you think you can't get electrocuted with out being grounded, why don't you get some rubber boots and stand on an electricians insulating rubber mat then grab on the active with one hand and the neutral with the other. You will be dead and the GFCI won't even trip. The current will run through you body from the active and the neutral and almost nothing will run to earth.

Dennis, I am not going to get in a ****ing match with you. I am a
Union Journeyman Wireman with over 20 years of experience. What do you think you are doing when you grab the hot and the neutral wire? In the National Electrical Code the neutral is actually called the "grounded" wire. The bare copper is the "Grounding" or "Equipment Grounding" wire. I'm not going to argue that one would get shocked if they did what you said above, because you are completing the path to GROUND. As far as the airplane, the skin of the airplane is grounded to the frame. The reason the bird would get fried if there was a"gap" in the wire is because it would now be considered part of the conductor, which in order to complete the circuit is grounded at the transformer or power generation equipment.

GFCI's in our country are made to trip at 5ma.

Point is, that in order to ensure that stray voltage will not have an effect on your fish is get a grounding probe.

[DennisRB]

The point is your body does not need to be grounded for you to be electrocuted, and you can be electrocuted by becoming part of the circuit without touching the ground. You failed to address that.

[Zephrant]

Good information all- Let's try not to get too wound up though, it causes strong magnetic fields that can hurt the monitor. (Electrical joke, never mind if you don't get it. ) :)

Thanks for the info on Lateral Line too Bigbob.

Interesting information about the pools in Australia- I had not heard that before.

Zeph

[DennisRB]

I wasn't out to get anyone into "a ****ing match " or anything. I was just sharing the information I have learned via my experience and continual training as an electrician. I went to the trouble of explaining things beyond vague statements for anyone that might want to know. I elaborated on certain issues that did not make any sense to me and were incorrect (or at least written in a way that could be open for debate) I can only speak for what I have learned in Australia but I expect the laws of physics to be the same world wide.

We call conductors in domestic installations, active, neutral and earth (ground). Since the earth wire is a different color and is run separately to the neutral wire we give them different names. Makes sense hey? In situations like automotive etc, we do call the neutral ground because it is connected to the chassis of the car but in this case there is no third earth wire to confuse "ground" with. However I assume the domestic wiring system to be very similar in the US.

In Australia we use the MEN (multiple earthed neutral) system which means that the neutral is connected to earth anyway, but it connects in the switchboard (fuse box) before any protection devices. So if you grab the active and the neutral you are effectively grabbing an earth anyway, but my point is your body does not need to be earthed (grounded) independently for you to get shocked. The same thing applies to fish, or anything for that matter. (you would still get shocked without the MEN link anyway)

For anyone that wants a 3rd opinion, heres a few links about Faraday cages and lightning strikes in planes and cars. It correctly explains why you are safeish in a plane or car. (remember a car is "grounded" through its tires. Lightning blasts through tires like a hot knife through butter)

http://www.physics.gla.ac.uk/~kskeldon/PubSci/exhibits/E3/

http://en.wikipedia.org/wiki/Faraday_cage

http://www.lightningsafety.com/nlsi_pls/vehicle_strike.html


This one goes one step further and says that its more to do with the "skin effect" than the Faraday cage. The skin effect is the tendency for high frequency currents to accumulate of the outer surface of a conductor.

http://www.mos.org/sln/toe/cage.html

Have a read if you are bored. If anyone has any specific questions, feel free to ask. If I know the answer I will be happy to help :)

PS, its lunacy to say fish are impervious to electrocution. It's good to see that almost everyone agrees on that.

electric eel link (http://hypertextbook.com/facts/BarryLajnwand.shtml)

"The high intensity charges are used for stunning or killing smaller fish. The charge is also used for the eel to defend itself."

[tanksalot]

As everyone must agree, stray voltage will take the path of least resistance to ground. If a fish's body is less conductive than the salt water around it, then the fish CAN'T get electrocuted (in the water). The current preferentially flows around the fish.

A local person got electrocuted while vacuuming his flooded basement with a wet/dry. The reason he did was because he was barefoot in the water, the cord got wet and his feet and legs (the most conductive surface going to ground) conducted the voltage to the soil through his feet. If this had happened and it was salt water, he could have possibly survived because then his legs might not have been significantly more conductive to ground than the salt water all over the floor touching the ground.

This topic seems to have the potential to spark a lot of heated discussion. (sorry).

tanksalot

[tanksalot]

As everyone must agree, stray voltage will take the path of least resistance to ground. If a fish's body is less conductive than the salt water around it, then the fish CAN'T get electrocuted (in the water). The current preferentially flows around the fish.

A local person got electrocuted while vacuuming his flooded basement with a wet/dry. The reason he did was because he was barefoot in the water, the cord got wet and his feet and legs (the most conductive surface going to ground) conducted the voltage to the soil through his feet. If this had happened and it was salt water, he could have possibly survived because then his legs might not have been significantly more conductive to ground than the salt water all over the floor touching the ground.

This topic seems to have the potential to spark a lot of heated discussion. (sorry).

tanksalot

[JENnKerry]

Ok...now how much salt are we talking? You say that salt water will be more conductive right? I was in the middle of a Hypo treatment. I was down to 1.009, we are talking literally almost no salt at all.
I just lost my clown today...I guess he was injured and hung on for a few more days.
All I know is, I got shocked, my fish acted quirky and died.
Damn...my yellow tang darted so fast he smacked into the glass, knocking himself out, then died 4 hrs later.
I witnessed this first hand so I know that the electricity had played SOME part in the loss of all of my fish.
Thanks to a Marineland Neptune Heater, I am down to "1" four striped Damsel. The first fish I started with 4 months ago....paid a whole $3.75 for him.

I have been keeping tanks for 20 years now and Im only 27, so I have been doing it my whole life. NEVER ONCE have I EVER EVER come across this kind of problem. I only used glass heaters. I put a titanium one in my 55 salt, but was using a glass one for my fresh.

Is it maybe because salt is more corrosive that it gets into the heater and causes malfunctions?

Again, I was down to 1.009 during the Hypo treatment...in that amount of salt does it LESSEN in conductivity? Therefore making my fish more suseptible to electicution???

[tanksalot]

That's a very interesting experience, and I have NO clue as to how, from a physics standpoint, that happened. I can't argue from your observations that the electricity affected the fish. I suspect the low s.g. played a role, but, from my understanding, unless the fish was sitting on a rock that was connected to ground, it would be oblivious to the electricity. You, of course, were grounded and felt it.

Oh well, I guess I go back to feeling stupid. I THOUGHT I knew what I was talking about, but apparently there's some other process at work here. What it is, I haven't a clue.

tanksalot

[JENnKerry]

The only thing I saw them touching was the rock decorations and the glass. They seemed to act like they had itchy faces and bodies. But as soon as I unplugged it, they stopped scratching.

I know that Marineland will be contacting me will their findings.

[ssheipel]

I'm not an electrician -- in fact Mom wanted me to be a plumber. Not that either.

But that aside, the discussion between the two electricians was just plain excellent.

Nothing better than two experts debating and explaining. Really.

I'll equip my new tank appopriately and could have been told that simply and quickly, BUT it would not have been as entertaining or informative.

Thanks guys!

Oh, and sorry about the electrifi..., er, fish killed by electricity going where it shouldn't have been.

steve

[DennisRB]

Sitting a fish on a rock wont do anything to connect it to ground. The current does not have to got directly ground anyway. It can go directly from one appliance in you tank to another.

The fish will be already be grounded by the water which is conductive (assuming your tank is not insulated from the ground). Look at all your appliances, they might be sitting on rubber feet on insulating carpet, but they are still grounded by the earth (ground) wire. I would say that salt water is much more conductive than rock, so the water acts like a earth wire to ground your fish.

The theory about the fish being safe because they are more resistive than water sounds good. But there simply won't work in real life. If the fish has more resistance, it just means that LESS current will flow through the fish, not none. A small current through a living being can kill it gradually by shutting down its nervous system. Just like the people in my pool example who did not even know they were being electrocuted and died gradually.

BTW chlorinated water is quite conductive but it did not save them by the "more resistance than water theory" Remember this happened with a low voltage system that was above earth. (earthing your self won't cause electrocution) With a huge water volume do disperse the current.

imagine a poor fish with 110-240V getting blasted in a 4 foot tank. Anyway an electric eel kills fish in water, the more resistance than water theory does not save them.

from http://www.vigyanprasar.com/wos/Fishes.htm

"There are fishes like torpedo, narcine, astrape, electric eels, electric catfishes, and star-grazers which possess electric organs. Fishes are the only creatures which have electric organs. Electric organs of the fishes are modifications of mussel. A large average size of electric eel can discharge about 550-600 volts. Electric fishes use their unique organs to stun other fishes which fall prey to them. Further beside being organs of offense, the electric organs may also act as defensive organs."

Strange that fish are the only animals to have electric organs. Seems very strange if their fishy food can't get electrocuted?

The eel kills with one quick shock (the average eel produces around 100V, but have bee recorded up to 600V) If can kill with one shock, how are your aquarium fish going to like a continuous belt of electricity.

You might argue that the eel is a freshwater fish, but some of the other electric fishes mentioned are marine. And besides fresh water is an good conductor like salt water. It definitely is not as good but its close enough to kill, too close for it to be a life saving factor anyway. Ok, before someone says pure fresh water is not a conductor, I will say that any water you would find in nature, specially the marshes where the eel lives would be quite conductive due to impurities.

I just done an experiment with an insulation tester I used some FW out of a FW tank and some SW. The FW shows a fair higher resistance on the ohms scale, but when you put it on the 250V insulation test, the FW conducts very well indeed.

[Conano]

this information is very intresting. But i have to ask a question. Will not the introduction of an electrical current produce what is a known acid such as sodiumhydrocide? or somethign to that effect... i dont remember much from highscool, but i remember something about current being added to saltwater formed some kind of Acid.

[MasterReef]

Fish can be electrocuted or, more commonly, become stressed with the presence of and electrical charge.

Is grounding required for electrocution - No, but current flow is . . . current can flow from a higher voltage potential to lower without a connection to ground.

Electricity takes the path of least resistance - yes but not all of it . . . electrons will take multiple paths ( ie a parallel circuit with a low resistance and a high one. More electrons will take the low resistance path in inverse proportion to the resistance value).

Fish have a higher resistance than saltwater . . . (I never measured the resistance of my pets but perhaps I should) I doubt it - my bet is that most creatures are even more conductive than the water they live in.

I use a groud probe and highly recommend them . . .JMO

[JENnKerry]

Well Marineland received the heater and found a hair line crack. I dont know if that happened during shipping or that was the reason for the stray current.
Either way, they took responsibility and gave me $100 credit to use for anything that I wanted.
Unfortunatly I dont want anything that I absolutly needed, so I settled for $100 worth of salt.
Hey, at least they were cool about it and felt bad for my fish that suffered.

[brian3]

Bottom line is you do not have to be grounded to get electrocuted - period. All you need is current to flow through your body (especially through your heart) to kill you. This current can be flowing to ground or not. Example - they repair high voltage lines by suspending a person from a helicopter. The person can touch the line even if it is over 100,000 volts without any problems, just like a bird does all the time. The problem is when the line breaks and he is holding one end in one hand and the other end with the other hand or a bird touches one line with one wing and the other line with the other wing. The current will flow through his body (and heart) just like he was a wire (although he has higher resistence than a wire). This will then kill him even though he never touched ground. It is all about current flow though the body, the ground is just the easiest place to generate this flow but not the only way. I've been an electrical engineer for 15 years and feel confident of the answer, although I am certainly not saying I'm never wrong.

[reefeater]

I, by no means am an engineer, just a lowly electrician, but what you discribed above brian3 is confusing me. The first thing is, I would like to see the man that could hold onto both ends of a very high voltage line, like the one you discribed above. The tension on the line is so great that it would rip him in half. I know the man is now part of the conductor, but doesn't the wire eventually end up going to ground down the line, say at the next transformer or sub-station? The other example you gave of the bird touching touching one line with one wing and the other line with the other wing is creating what is known as a phase-to-phase short, meaning with alternating current effectively grounding out. If I am misunderstanding this concept please let me know. I have been a union electrician for 17 years and that is the way I have always understood it.

[brian3]

Yes that is true a man would get ripped apart is he was holding on to two ends of a high tension line. I guess that was not the point. You can get current flow from one voltage to a different one. Use DC current for example. You will get current flow if you hook the positve lead of a 24 volt battery to the positive of a 12 volt battery tying the negative together of course to complete the path. Current flows from the 24 to 12 because of a difference which creates the current flow, not necessarily to ground. The batteries do not even need to be tied to true ground for this to happen they both could be floating in air (assuming they could of course or even in a plane). Using the bird example it is a line to line short, one voltage to the other creating a difference, not necessarily ground. Current flow goes from one voltage potential to another of different value, the direction depends on which is higher and since the typically are of different phases they are different values at any given time. Certainly not trying to argue just pointing out some examples that is all.

[reefeater]

I understand what you are saying. I guess the correct way to put this, is that electricity flows from the greater potential to the less potential. I don't think we need to get into the electron flow in this forum. It was interesting to see everyones opinions and impressions on grounding and electrocution. Point is, that a ground probe, IMO, is an intragual part of your aquarium system. The only problem with using a ground probe is that you still have to keep an eye on your system, because it can mask the problem of voltage leaking into the tank.

[brian3]

Reefeater,
I agree and yes I do believe a ground probe can mask a problem and many don't know they make have an issue with a powerhead or the like.

[Dwayne]

Originally posted by reefeater
Point is, that a ground probe, IMO, is an intragual part of your aquarium system. The only problem with using a ground probe is that you still have to keep an eye on your system, because it can mask the problem of voltage leaking into the tank.

If we agree that a grounding probe is a really good idea, then wouldn't an amp meter between the probe and ground be a good idea?

If the grounding probe takes all stray and other unwanted voltage to ground, we may not notice it. If an amp meter were put inline, we would have an indicator of current. Current would indicate the presence of voltage, which means something is wrong.

Thinking about this. The 'amp meter' could be nothing more than a LED. Just some type of indicator. Maybe we need grounding probes with current indicators.

[Bayliner]

Dwayne,
I think that's an excellent idea.
At one time large power distribution systems used lights on the ground legs to help detect a ground fault.

I am surprised nobody has developed a ground probe for the marine industry with a detection light in it.... maybe you should patent that idea.....

Cam

[DennisRB]

Lets try to asses what the ground probe does, and what it is actually beneficial for.

The way I look at it, it only protects YOU and not your fish. In fact under some circumstances it may be bad for your fish. If you have a GFCI and a ground probe, your CFCI will trip as soon as you have an active wire exposed in the tank. Thats the only benefit I see. I'm not saying its no good (protecting yourself is a good thing). Just trying to put it into perspective.

If you use a ground probe with no GFCI you might introduce a current into the tank that would not even be there without if you had left it off! Example, with out the probe your tank may be well insulated from the ground via the glass and wood carpet etc. If you livened it up with an active you would raise the voltage in the tank but only a small current if any would flow. (think of bird on a wire) Adding a ground probe would complete the circuit and cause current to flow from the broken active to the ground probe. Any fish in between would not be happy. If your lucky, the current flow will be big enough to blow your fuse or trip your circuit breaker. The probe in this scenario would still help to save YOU, but it would be bad for the fish.

I could be wrong, but it all seems to make good sense to me.

[Dwayne]

DennisRB - I think you're right, at least the way I understand things. That's why I suggested an indicator of some sort that would alert you to stray or not so stray voltage existing in the tank.

The idea came from a electrical tester I own. It really is nothing more than a piece of wire with two LEDs in the middle (I'm sure there is some small ciruitry around the LEDs). It does nothing more than indicate the presence or absence of voltage, AC or DC.

Again, just an idea and not much more than that.

[DennisRB]

What you suggest is basically the normal way for checking for potential above earth. I do it at work all the time. I just use a meter to measure the potential difference between earth and the object in question. The meter also has a 10K ohm resistor in series to bleed of any static charges caused by induction etc (this is probably not a huge issue at home but in my field it is). If I do find small voltage I move the meter to the amp position and measure the possible fault current. This is only a good idea with low voltage readings, if the voltage reading is high (IE a complete break in an active) it will blow the meter up because it acts like a dead short on the current setting.

You could use a lamp instead but I would not trust it. An LED would blow if there was a decent fault, and a incandescent won't light up if there is only a minor fault. (however you could make a special circuit so it would work) I would just use a GFCI and let it be the measuring device in conjunction with a ground probe for increased reliability. The GFCI will indirectly measure the earth current and trip out at its specified value.

[ObtuseWit]

I'm just a lowly old electrical engineer, BSEE/MSEE Univ of Texas, PhD. Rice Univ. I have only been designing and working with electrical power systems for 30 years so I have been patient long enough. Rumors, misconceptions and 'experts' abound!

Current FLOWS in the bird, even when it is not grounded. WHY?? because Kirschoff's Theory of nodal current flow. There just isn't enough current to kill the bird. Voltage doesn't kill, ONLY current! The formula for parallel current is (btw I am going to use DC current so we don't have to mess around with the trigonometry of a sine wave)

Bird = R1... current through bird = I1
Wire = R2.... current through wire = I2

Ohm's law
I (current) = E (voltage) / R (resistance)

Parallel resistance
Rt (total) resistance = (R1 + R2)/(R1 x R2)

therefore

It (Total Current) = Rt/E


Current through Wire = I2= It (R2/Rt)
Current trough Bird = I1 = It (R1/Rt)

Since the resistance of the wire is VERY LOW maybe .000003 Ohms for an inch of aluminum

AND the resitance for the bird is very high... say 200 ohms ( a human is about 1000 ohms hand to foot)

Then, there is current flowing in the bird, just not very dang much, certainly not enough to kill it or cause it discomfort

The same holds true for a fish in saltwater, there is not enough current to kill it. An electric eel stuns its prey by generating an electric field. In fresh water, the resistance of the fresh water is sufficient that the prey tissue, saturated with salts (ever taste your own blood???) has less resistance than the surrounding water so current flows through the fish. This is caused by a phenomonon known as 'offset potential'. The voltage at one end of the fish is greater than at the other end so the fish will have current flowing THROUGH its body.

For those doubters out there... put a molly in saltwater in a white plastic bucket (NOT black since they have carbon which is not an insulator) drop a 120 volt hot wire in the bucket, without a neutral! just the hot wire!

If the molly dies from electrocution, I'll buy you a new one... If you hear it complain, by all means see your therapist

As a side note, the rotating magnetic field generated by in-tank powerheads is probably more detrimental to your fish than stray voltage. That is not to say areas of potential in the tank will not have a strong effect on its nervous system. You might think adding a ground probe will protect you from being electrocuted, but that ain't necessarily so, it might. It will increase current flow in the tank, which will lead to areas of greater and lesser potential and your fish just may suffer the fate of the electric eel prey.

Best practice, keep electrical equipment out of the water, use mag coupled pumps, throw away your powerheads and your fish and corals will love you for it

Nuff said

[DennisRB]

I agree with almost everything you said, I even said most of it myself in one way or another!

However you do seem to contradict yourself when you say that fish cannot be electrocuted, then you say they may suffer the fate of electric eel prey.

So, are you agreeing with me about fish being able to get electrocuted with a ground probe connected, if it swims in between the probe and the broken active? (I do realize that the large majority of current would flow around the fish, but it only takes a bit of current to kill over time)

I also said that the fish probably won't die if you do what you described with the active only in the bucket.

What about if you put the active in the bucket and a ground probe or neutral on the other side with the fish in between? (I'm not sure if that will draw enough current to set of the fuse/breaker, assume there is no GFCI) Just say that it doesn't trip the breaker and you get a 20A current through the bucket with the molly in the middle. I agree that almost all the current will flow around the fish. But I don't think that the difference in resistance between the fish and the water would be large enough to save it (I could be wrong, this has been the basis of my argument). I don't think it could be compared to a bird on a wire. Sea water has a much higher resistance than an aluminum cable and a fish has a much lower resistance to a bird (I haven't tested it but it seems obvious that a fish has much less insulation than a bird, think of the scaly legs of a bird compared to the gills of the fish, the current could enter the fish quite easily and kill it if its resistance of its flesh is low enough)

I am guessing that the current flow through the fish would be great enough to kill it. Possibly not right away but I reckon it would die. In any case It couldn't be good for it!

Thoughts?

[ObtuseWit]

This poses an interesting question and one which deserves some good 'ole 'rithmatic.

Conductivity through a substance is measured in siemens or microseimens (siemens x 0.000001 = µS). In seawater, at the standard concentration of S35, at 28 deg C gconductivity is 57,015 µS/cm. (Changing the temperature changes the conductivity only slightly so it will be ignored.) Wet skin is about 43,000 µS/cm, bone is around 200,056 µS/cm, blood is around 1,200,000 µS/cm, all tissues averaged are about 198,000 µS/cm.

ohms = 1/S or 1/(µS * 0.000001) therefore Mr. Fish = approximately 1/0.198,000 or 5 ohms/cm

Let's make a couple of assumptions
Assume the fish and seawater are a simple parallel circuit
FISH
1. The fish is 10 cm in length ~4 inches
2 The cross sectional area of the fish is 5 sq cm 1cm wide x 5 cm tall (a tang??)
3. The resistance of this critter is ~ 5 ohms per cm (length)(approximate resistance of living tissue)

WATER
1. Contained in a ten gallon tank 10 x 10 x 20 = 645 sq cm cross sectional area, 50 cm length
2. Current flow (electrical) through the tank is uniform

The fish would equal approx 50 ohms 5cm x 10ohms/cm

First the flow of electrical current in the tank (ignoring the fish)would be

Ohms/cm for saltwater = 1/(57015 * .000001) = 17.53
total resistance = 17.53 * 50 = 876
total current @ 120v = I(current) = E(volts)/R(ohms) = 120/876 =.1369 amps times 1000 = 1369 milliamps (ma)

Now, let's assume the worst possible case. a simple parallel circuit with this poor fish of 6 square cm cross sectional area being forced to live in a tank of 12 sq cm (~1" x 2") crossectional area (6sq cm of fish and 6 sq cm of water) x 20 inches long (here come the Tang Police) with the total length of the parallel circuit given at 4 inches.

10 cm of seawater = 175.3 ohms Rt
10 cm of fish = 50 ohms Rf
Kirschoff raises his hand, %of current through water thru the fish = 175.3/(175.3 + 50) = 77.8%
there fore the total current flowing in the water is .778 * 1369 ma = 1065.18 millamp
critter current = 1369-1065 = 304 ma or 22.2% of 1369 ma
Mr. Kirschoff is happy that the total current is still 1369 ma. Mr. Ohm might argue that the total resistance for this 4 inches of the tank is actually less than 4 inches of seawater because of his laws of parallel resistance so if we take that into account we have 2 resistances in series.

16 inches of water = 17.53 * 16 = 280.48 and
4 inches of seawater in parallel with the hapless victim
(Rfish + Rseawater)/(Rfish * Rseawater)
(20+70.12)/(20*70.12)=.06ohms

so at the least the total series resistance could be 281 ohms Rparallel circuit + Rseawater (16 inches worth) which gives a total current of 427 ma. meaning that the fish has 22.2% of 427ma or about 94 ma flowing through it.

In a human critter, it takes about 100 ma of current to cause cardiac disfunction, so the fish is prob gonna be dead, or at least really upset.

But we have failed to take one thing into consideration, the total cross sectional area of the tank. We have to comply with the tang police and not keep this poor thing in a tank 20 inches long by 1" x 2" (1" x 2" = ~12.9 sq cm) so lets move him up to the full 10 gallon tank

Let's look at the current density across the cross sectional area, which is somewhat more realistic than a parallel resistance circuit. Total current density in a 10 gallon tank, with an electrode of 10 x 10 inches on each end, will be approximately 1369 ma/ 645 sq cm = 2.12 ma/sq cm. Therefore our little fishy will have about 2.12 * 6 sq cm = 12.72 ma of current flowing in him, which is not enough to kill him, but it just might make him uncomfortable.

Since we are dealing with a single point source and a single point ground (when a powerhead shorts and there is a ground probe in the water) if these electrodes were in the top back corners of the tank, there would probably not be any detectable currents in the front bottom of the tank. And, even if the fish was directly between the 2 electrodes, he would probably not get a lethal dose, since the law of gradient potentials would prevail. The law of gradient potential is the theory that an electrical current is greatest at a center line between electrodes and declines logrythmically as its distance from the center increases.

Now lets talk about the electric eel again. Fresh water is 50 µS/cm so current does not flow through fresh water as well as it does in seawater. The eel creates an gradient potential (more volts closer to the eel than further away) and this is what makes a fish vulnerable to an electric eel shock. Current flows when there is a difference in potential from the point of greater potential (more electrons) to lower potential. Since fresh water does not conduct electricity well, its avg. conductivity being 50 µS/cm (99.999% pure water i.e. RO/DI is almost an insulator at 0.0548 µS/cm), there is a great potential difference over the length of the fish than in saltwater. He gets a shock as current flows through his lower resistance body and more conductive tissues(due to salts in the tissues). An electric eel would probably starve in saltwater because he would not have the potential gradient required to generate an electric current flowing thru the fish of sufficient magnitude to affect the prey. The current flow through the saltwater would be more than through the fish.

Is everyone thoroughly confused now???

While it may not be a good thing to have those stray joltages running around your tank, chance are slim you are going to give Mr. Tang "the chair".

[MasterReef]

It (Total Current) = Rt/E?

Must be a typo . . . It=E/Rt not Rt/E

.1369 amps times 1000 = 1369 milliamps (ma) ?

.1369 A = 139.6 ma not 1369ma . . .

[DennisRB]

Cool, if I knew the resistance of saltwater and of a fish I would have worked it our myself. Cheers for that.

One question... I have always been trained that 30ma can kill a human. Don't you think the 12ma fish would eventually die of electrocution, given there greater sensitivity to electricity? I have always been taught that smallish currents can kill over time in regards to humans in a pool, IE the fish might die in a few hours with 12ma in it. I think it would decrease its life span at best.

What do you reckon?

[ObtuseWit]

OOOPS...yep definitely a typo on the milliamps... and (I) definitely = E/R Ya'll can do the math
thats what I get for reefing while working... A strong arguement for retirement..and here is the skinny on death by electricity, at least for humans. OSHA still hasn't begun safety regs on fish...


Current Reaction
1 ma Perception level

5 ma Slight shock felt; not painful but disturbing

6-30 ma Painful shock; "let-go" range

50-150 ma Extreme pain, possible respiratory arrest, severe muscular contraction

1000-4,300 ma Ventricular fibrillation

10,000+ ma Cardiac arrest, severe burns and probable death

[ObtuseWit]

well, redoing the math with a decimal in the correct place yields 30.4 ma in the first scenario and 1.272 ma in the last 139.6/645 = .21 ma/sq cm. Which tends to make Mr. Tang all the more safe.

You will get no arguement out of me that stray electrons are not a good thing. Any amount of current is not a good thing, but ,as i indicated in my first post in this thread, I don't even think the magnetic field from a powerhead is a good thing to have in a tank. I haven't used them for years. Da place for da pump is in da sump...

[DennisRB]

I agree 100% about no electrons being a good thing.

Those figures you posted are for quick shocks. What about if you had them going through your body permanently, like a fish would in a tank. I was always trained that there are 3 factors when it comes to electrocution. Amount of current, Part of your body though which it flows and the amount time the current flows through you body.

[ObtuseWit]

Testing in this area is somewhat lacking but the electrical safety gurus base all shocks on 3 cycles. The reason for this is the nature of protective devices. Circuit Breakers take about 3 full cycles to "see" the current build to trip level at a fault and another 3 cycles to clear the fault. Safety levels for human safe current threshold are based on a 3 cycle exposure, that is .048 seconds. There is no evidence that low current levels (safe levels) over a prolonged period cause any more damage than a 3 cycle hit at that level. However, there is a mountain of evidence that shows high levels of current can be fatal in as little as 1 cycle which is .016 secs.

GFCI circuits are designed differently and trip at an unbalanced condition of 6 ma or less. The theory is that this will not allow a fault current to reach a sufficient level to cause injury. Because of its name, it's frequently believed that a GFCI detects fault current. In fact, it detects differential current. If there is fault to an isolated conductor, such as the water in a tank, and there is no current flow to ground, a GFCI will not trip. The UL standard for operation of a GFCI is 200 ms, sufficient time for a large current to cause cardiac arrest. GFCIs are to prevent a person from being trapped by a 'let go' current, which is a current of sufficient magnitude that the person is unable to control muscle function, i.e. he isn't able to let go of an energized conductor. If you come in contact with that high potential and are solidly grounded, you can still be electrocuted before a GFCI trips. This makes a good case for a tank ground probe so stray potential has a path to ground. But, if you are not using a GFCI, current through a circuit breaker may not ever reach a current level sufficient to trip, in fact it probably won't, even with a ground probe. Ground probe's without a GFCI will not protect you. A GFCI without a ground probe may not protect you.

Bottom line, keep anything electrical out of your tank, use external pumps, put anything electrical that must be in the water, such as heaters, in a sump and protect it with a ground probe and GFCI.

[DennisRB]

"Ground probes without a GFCI will not protect you."

I would say that the level of protection is not the best but it would protect you somewhat by giving an easier current path to ground. If the tank is livened up and the breaker has not tripped the probe will help to limit the current though your body by giving a low resistance parallel path. The helpfulness of the probe will be dependent on how close from the probe you put you hand in the tank. If you touch the water right near the active break in insulation it won't do much to help, but if you touch right near the probe you probably won't feel anything as the water in close proximity to the probe would be close to earth potential. IE the closer to the probe you touch, the safer you will be.

If the there is a damaged appliance in one end and a ground probe in the other, you could think of the water as a big resistor. There would be 110V near the appliance and close to 0V near the ground probe and 55V in the middle of the tank etc etc (approx)

You could put a probe on each side of the tank to increase the effectiveness. If your lucky an appliance will blow close enough to the probe to trip the breaker. This will work even better if the circuit is already running close to its maximum (which a lot of reef tanks circuits are)

In any case, you won't be fully protected but it's better than nothing.

[surfy]

My head hurts now,LOL.

What is this, µS? And how did you type it:D

I really suck at math and electricity so I had no clue to what you were talking about in your example. I know where it was going, just don't understand 100% of your math there.

Anyways, I have never seen a grounding probe before. What exactly is it? And how do you set it up?
I know what it does but I'm just trying to get a mental picture of it.

Is it just a probe (inside tank) then a wire from probe to the ground wire on the GFCI? Or is there a ground "rod" that you stick into the ground on the GFCI instead of directly wireing it to the ground?
Or am I completely wrong?
Thanks.

[ObtuseWit]

µS is the sybolic representation for micro Siemen. Electrical conductivity, which is the capacity os a material to conduct an electrical current, is measured in Siemens. A µS is 1 millionth of a Siemen.

And to type symbols, you can either copy them from Character Map, which is a Windows feature, or you can type in The ASCii command of ALT + (4 digit Unicode numbe) or copy and paste the character from the character map. See Windows Help files for information on Character Map.

Titanium Ground Probes are availabel at your LFS and online

[surfy]

Yeah my LFS's don't carry them, I'll just have to do some online shoping.
Thanks.

[ladyshark]

JenandKerry

Glad the lfs at least compensated you at least.

Sorry for your loss--very sad

My heater blew in the tank--at least the glass burst into big pieces that fell in the tank. I was there, so immediately unplugged and removed the glass.

No problems from this, but maybe I was just lucky, or whatever current was not live for long enough.

[reefeater]

ObtuseWit, now that you have made us lowly "experts/electricians" sound like idiots and yourself sound like a genius, did you really say anything differently than what was said before? all you managed to do was use a bunch of formulas (that very few people understand, or care to know) to prove your point. I think this entire thread is way off target. Like you said before, the best thing to do is keep all electrical parts out of your aquarium water. If you have no other alternative, use a ground probe plugged into a GFCI recept. and that will provide you with the most protection possible.

[ObtuseWit]

Well, reefeater, I certainly did not say that any electrician was lowly or an idiot. Those are your words. Sorry you feel that way. For those who people who can't understand all the math, I think I spelled out the bottom line. There are some people who can follow the math and the formulas, and have the desire to better understand the why and how of it all. I could have very well have made the comment that a GFCI doesn't so you any good without a ground probe, or that a ground probe doesn't do you any good without a GFCI., but I am sure that someone would have come along and said "prove your point". And I could have kept my mouth shut and let someone get injured or even die from electocution, but I did not. I took the time and made the effort to share what I know and document the reasons why for those people who have the desire to increase their knowledge base.
And just so you know brother....
I am a member of IBEW LU 479, and carried an IW ticket for many years. Old Yeller made me enough money to get an education, which took a lot of years and a lot of nights. It took 11 years, 2-4 nights a week in class to get my BSEE, after running conduit and cable tray all day in a refinery or chemical plant. To get the MS took another 4 years, driving 80 miles one way 2 nights a week after working all day. I am certainly no genius, I just worked my tail off to learn all those formulas, and I think enough of my fellow reefer keepers to share what I got from those years of hard work, just as they have shared with me over the years.

[bawsom]

I have GFI's on all my socks used for my aquarium, everytime I try and insert the ground probe it trips my GFI's. Any ideas?

Thank in advance

[ObtuseWit]

unplug everything from the gfci and install the ground probe. Plug each device in one at a timer until the gfci trips. You can then isolate which device has a problem and replace it. Most people see leakage in powerheads or heaters. If you can't get anything to power up without the GFCI tripping, you might want to check out the possibility that the GFCI is bad.

[bawsom]

Thanks a lot ObtuseWit will give it a try

[Tunjee]

I just read through this article completely. Liars never figure but figures never lie. ObtuseWit you proved reefeaters point with actual figures. Right on! At least that's how I see it. This discussion is indepthly corrosive to my brain, will keep me thinking =)... but back to the subject at hand...Why did JENnKerry's fish die??? Coincidence a hairline fracture found in heater? Was their tank grounded and on a GFCI?

[jeffbrig]

Originally posted by Tunjee
... but back to the subject at hand...Why did JENnKerry's fish die???

It will be hard to say for sure. I like ObtuseWit's analysis, very thorough. I will throw out another possiblity. Any stray current, while it may not "electrocute" a fish, generates a magnetic field. The strength of the field is tied to the magnitude of the current, and the fish's exposure to the field is dictated by its proximity to the current source. What effect this magnetic field may have on a fish's nervous system is difficult to say. And obviously, some will be more affected by it than others.

[DennisRB]

Living organisms nervous systems relies on chemical and electric impulses to work. Not magnetic. I'm sure that strong magnetic fields would be bad for the long run but they are not that bad. Has anyone ever had a MRI? I need one soon for my knee. I had to get an eye X ray because I said I have used a grinder. The magnetic field in an MRI machine is so strong that it could rip any small shards if metal through my eye causing blindness. I doubt a magnetic field could kill a fish in a normal tank situation.

Anyway it good to see I have been called a liar and that figures are the only way to go. Now lets see if figurers can argue against this.

[DennisRB]

A few seconds later.

That is one unhappy toad fish. Maybe it was the magnetic field, maybe it was osmotic shock, maybe there was not enough oxygen, maybe electrolysis changed the water to acid, or maybe... just maybe it got damn electrocuted!

The water was directly from the ocean.

[DennisRB]

I'm not even arguing that JENnKerry's fish did die from electrocution. I am merely trying to point out that small currents through a living body can kill over time. It took about 5-10 seconds for the toad fish to float belly up to to top of the bucket. I immediately stopped the test and the fish remained paralyzed for about 5 seconds and partially paralyzed for about 2 minutes. It took about 10 minutes to return to its normal behavior. There is absolutely no doubt that it would have died if I left the power on for longer. I reckon another 10 seconds would have finished it off. This is with 240V and a GFCI! Like I predicted it did not trip. Fitting a ground probe with not GFCI would result in a situation similar to my bucket.

A situation this bad would probably not happen in a tank, but the point is given the right conditions a salt water fish can die of electrocution in the water. There is NO DOUBT ABOUT IT. All it would take is for it to swim close to the fault and stay there for a while.

Remember this fish had a high current but it only had to endure it for 5-10 seconds. A fish in a bad electrical tank situation would have less current exposure but it has to endure it permanently and this is not good. If i done the experiment in my tank would the fish have dropped dead right away? I don't think so. Would they have died eventually. I believe that they would have eventually succumbed to electrocution or at best have dramatically reduced lifespan and erratic behavior.

I feed bad for the fish, but he seems to have recovered OK. I hope this experiment saves a few more fish in the future.

[DennisRB]

My pics are gone

[Dwayne]

Let's not turn this thread into a flame fest. This has been a very good debate and I would hate to lockdown a useful thread. Let's stick to debating the facts.

Simple abstract of this thread as I see it:

Can fish be eclectrocuted? Yes

Can a tank have stray voltage and not trip a GFCI? Yes

Can a tank not trip a GFCI with a grounding probe? Yes

Should you have a GFCI and a grounding probe? Yes

Do we know why JENnKerry's fish died? No.

[JENnKerry]

One thing that I do know is that for a FACT is I GOT SHOCKED. So, that current was running through the tank the moment I stuck my hand it. How long it was like that, I dont know.

But, I had my fish in that QT for 3 weeks at that time, never once witnessing any type of stress that would have sent them sailing.
Then within 3 days, all the fish act very strange and darty and died.
Im leaning towards the uncomfortable jolt of electricity that caused these fish to finally stress and die.
My Goby found the only 1 inch opening and jumped. Now, Gobies are known for that, so if that was due to a current, we will never know.
I did infact witness my tang dart across the tank from one end to another SLAMMING into the side of the tank, knocking itself out. It came to a few min later then ultimatly died within 4 hours.
That was the oddest thing I have ever seen.
I didnt stick my hand in the tank at that point, I used a net that had a rubber grip to get it out.
It was when I had to take a hiding rock out because the Flame Angel died inside of it.
My fingers hurt for about an hour after that shock, it went right up my forearm.
If thats what I felt...what did they feel?

[Tunjee]

DennisRB , I'm not calling you a liar. I"m trying to get to the point here. If you have a grounding probe and a GFCI on a 120volt system. Can your fish still die of electroctution?

[Dwayne]

Originally posted by Tunjee
If you have a grounding probe and a GFCI on a 120volt system. Can your fish still die of electroctution?

It seems it is possible to have stray voltage/current not sufficient to trip a GFCI in the tank even with a grounding probe. From this discussion, I would say the effect on a particular fish depends on the amount of current, type of fish, and the amount of time the fish spends in the current path. I think all 3 would play substantial roles in answering the question.

If JENnKerry's fish were effected by current in the tank (seems they were), then if the type of fish or swim pattern of the the fish played no role all fish would react the same. Since they reacted differently, I would think the type of fish and/or swim pattern does matter.

[jeffbrig]

Originally posted by DennisRB
Living organisms nervous systems relies on chemical and electric impulses to work. Not magnetic. I'm sure that strong magnetic fields would be bad for the long run but they are not that bad.

Okay, let me develop my original thought a little further, I don't think I explained myself very well. Current, magnetic fields, and electrical (EMF) fields are all tied together. The current flow induces a magnetic field which induces an electrical field, etc. etc. The fields created can even induce a current flow in another nearby conductor, assuming proper orientation and small distance. This could potentially have an impact on the electrical impulses in a fish's nervous system. I say potentially because obviously it all depends on the strength/magnitude of the field. A sufficiently large current could theoretically create a field strong enough to cause a problem. Whether or not that's possible in the situation described here is another debate.

[DennisRB]

I had to learn all the formulas and theories for electromagnetic induction in my training. I doubt that the electromagnetic induction in a fish tank could induce a current in a fish large enough to do any real harm. Look at my MRI example. I'm fairly sure that if you can lay down in an MRI for 2 hours, any current caused in a fish tank would be incapable of harming fish. I'm not saying this is insignificant, but it won't cause electrocution. It might upset a fishes magnetic sense though, which could stress it.

An MRI probably creates the strongest magnetic field that any living organism would ever have to put up with.

MRI link (http://electronics.howstuffworks.com/mri.htm)

Let's not turn this thread into a flame fest. This has been a very good debate and I would hate to lockdown a useful thread. Let's stick to debating the facts. Although I was referred to as an idiot and a liar. I resisted the urge to flame anyone and don't have any desire do do so. My aim is to stop people from electrocuting themselves and their livestock. It seemed that no amount of debating was going to prove my point so I regretfully electrocuted a fish in the hope of preventing many fish being electrocuted in the future due to the false "fish are impervious to electrocution" line of thinking.

Simple abstract of this thread as I see it:

Can fish be electrocuted? Yes. I agree.

Can a tank have stray voltage and not trip a GFCI? Yes. Only if it does not have a ground probe, or if the current is below the GFCI rating, or if the current flows from an active to a neutral like in my test.

Can a tank not trip a GFCI with a grounding probe? Yes. I don't agree (under normal circumstances) It should trip if there is an insulation fault in the tank which causes current to flow down the probe to a level which exceeds the rating of the GFCI. If not there is something badly wrong with the setup. I would expect almost any insulation fault to trip the GFCI with a probe fitted.

Should you have a GFCI and a grounding probe? Yes You should use it in conjunction with a GFCI. The primary reason for it is to allow an easy path to ground to trip the GFCI. Using one without a GFCI might help to save you. (see my explanation in my previous posts) But it will be worse for your fish by promoting a current to flow though the tank in a fault condition. I explained this already in detail for those who have just joined us.

Do we know why JENnKerry's fish died? No. I don't know for sure, but it may well have been electrocution related, and probably was IMO. Some fish might not tolerate even the slightest current through their body's for all we know. Its obvious there has been no research in this area. For electrocution to have occurred, current would have flown through the tank, via an active and a neutral, or and active and an earth. This earth could have been provided by many things in the tank setup but I cant be sure if there was an earth or not. So I cant be sure whether there even was a current let alone whether the current through the actual fish would have been large enough to finally kill it.

DennisRB , I'm not calling you a liar. I"m trying to get to the point here. If you have a grounding probe and a GFCI on a 120volt system. Can your fish still die of electroctution?

The point is this subject has way to many variables to try and work out with figures. I proved that it is definitely possible to electrocute a fish is salt water with a GFCI in place without a ground probe. However I doubt that you could ever get a active to neutral fault in a tank that would not shoot a heap of current down a ground probe as well. So I seriously doubt that you could electrocute a fish with a ground probe and GFCI in place. It would trip pretty much as soon as there was a break in the insulation of any appliance in the tank.

I hope every one realizes that adding a ground probe with no GFCI will increase the risk of harm to livestock via electric current.

[mgregson]

Has anyone been electrofishing??? I volunteered with Fisheries a while ago and we did this for a week up in Hunter Region (New South Wales Australia)... You go out in a boat and drop some "tentacles" over the side and send a current through the water (cant remember strength)...

Anyway, the fish go nuts because the current messes with their muscle signals and are attracted (hmm...poor word choice- I dont think they have any choice) to the boat, then we scoop them out and can measure them etc...

Do you think the fish could have been "attracted" to the current emitting device (heater), and then grounded itself??

Regardless, I imagine a sustained current through the water, while not killing the animal straight away, will cause death fairly quickly...

[DennisRB]

Sounds like a cool way of fishing. :eek1: :smokin:

I don't understand why people keep mentioning fish grounding themselves? Whats there for it to ground itself on? The current would already be going directly to the grounded item regardless of the fish. The fish is swimming IN a conductor so it would essentially be electrically connected to any said grounding device by the water anyway. It has to swim between the current emitting device and a grounded item to allow current to pass through its body.

However the electrofishing principal may have attracted it closer to the heater which caused more current to pass through it because it was more in line with the path of current. Is that what you mean?

[Conano]

What does an MRI have to do with electricity other than the electricity nessicary to make the magnetic field?

[DennisRB]

What does an MRI have to do with electricity? Nothing.

Just in case you didn't catch on, an MRI subjects people to enormous magnetic fields without any harm. It shows that it is very unlikely that magnetic fields are the reasons for the fishes death. If people can endure the magnetic fields of an MRI, It would seem very unlikely that a fish would be harmed by a magnetic field in a tank, considering the MRI's magnetic field is thousands of times stronger.

[Conano]

i could be wrong, but the field that fish generate is not magnetic, it's electrostatic. I of course havent read all this thread, i found many post's rather tediouse and boring, not to menchon people explaining the same thing, just in different words. but yes, electromagnetic fields would not bother fish, however electrostatic fields would... IE a shark can "smell" a 9 volt battery in the water from a far distance. The word "smell" i mean there are micro pors on the sharks face and body, that sences electrostatic energy from it's prey, that energy is then transformed intoa brain signal. depending on where the energy was felt ont he sharks head and body shows the direction the fish, or electrostatic energy is eminating from. Perhaps electrostatic is the wrong word. it's more of a electric field discharge that the fish gives off. If this is wrong, then i blame my lfs. They explained it to me that way.

But i dont think an electromagnetic field would bother a fish. the electricity runing though the field coils might. but doubt the magnetic field produced by the coils would.

Of course i'm sure most of you already know all this. If i'm wrong, then please explain it to me. This is the way it was explained to me, as well as they way i've heard it explained on shows like discovery channel and such.

[DennisRB]

You must be thinking of ampullae of Lorenzini (http://www.mar.dfo-mpo.gc.ca/science/shark/english/ampul.htm) They are a sort of electrical receptor that sharks have to detect minute electrical disturbances.

Every animal generates small electrical signals in its nervous system. Thats what the shark picks up with its ampullae of Lorenzini. Electrocution occurs when these impulses are disturbed by current flow through the body.

No one suggested that fish produce magnetic fields, merely that they may be affected by them.

Unfortunately when it comes to electricity many people don't understand things and they have to be repeated. Either that or they just don't read whats written and make a comment that shows they don't understand what has already been established. It does get annoying continually repeating myself, and also reading what other people have written over and over again when they repeat themselves. A few posters in this thread have taken a fair bit of time to examine issues in detail, and it seems like a waste of time when someone makes a comment that shows they have not read it, or asked a question that has been answered 20 times. If people read the discussion before posting this problems would be lessened.

Electro static fields most commonly exist when 2 objects with different charges are close together. The charges attract but cant equalize because there is a non conductive medium between them. This is how a capacitor works. One plate is positively charged and one is negatively charged. The plates are separated by an insulator so the charges remain in each plate by attraction. Electrostatic fields hold them together.

I don't think that electrostatic fields would be able to exist in a conductive medium like water very well.

Click me for electrostatic flied. (http://whatis.techtarget.com/definition/0,,sid9_gci212048,00.html)

Anyway you can subject yourself to a few million volts of electrostatic charge with no harm to you. So I doubt the any minuscule electrostatic charge that you fish might have to endure would hurt them at all. Although electrostatic charges are probably not going to be to good for them either because they are probably much more sensitive to them than us.

http://amasci.com/graphics/billvgd2.jpg

Van de Graaff Generator (http://www.k12.nf.ca/gc/scienceweb/physicsweb/Physics3204/studentprojs/Project23/vandegraaff.html)