Electrical Safety: GFCI, AFCI, Ground Probes

[Tristan]

I know this is kind of off topic but it kind of has to do with stray voltage in our tanks.

Can someone help me out with a title for my project?

It's about "does salinity affect electrical conductivity?"

Its for my 7th grade science fair

 

[Paul B]

Why don't you call it. "Does salinity affect electrical conductivity"?

 

[Chibils]

I'm with @bevo5 - I want to know what I can do to make my system safe. I'm electrically illiterate. Most of the OP and 90% of the replies are gibberish to me. Right now my power strip is hooked to a GFCI adapter at the outlet, but I don't know how safe it really is. I'd be willing to get an electrician out and replace fish tank breakers with 20A GFCI or AFCI or CAFCI breakers. Just tell me what I can do.

Anyone?

 

[Paul B]

Push the test button on the GFCI adapter and see if the power goes off. If it does, you are good to go.

 

[klp]

For: Floyd R Turbo:
Could you reword the web article sections that need corrections to what they should state rather than just what is wrong with them? I would like to make sure I understand them correctly. Thanks for the excellent thread to everyone!

 

[Turbo's Aquatics]

Could you reword the web article sections that need corrections to what they should state rather than just what is wrong with them?

Can you clarify what you mean by "they" and "them"? I do need to redo it...

 

[Brew12]

Can you clarify what you mean by "they" and "them"? I do need to redo it...

First time I have seen this post. I think the majority of it makes sense in a perfect world but we do not live in a perfect world.
For instance, I didn't see anything about salt creep, or algae build up. If you don't use a ground plug these can still cause current flow through your aquarium. Even the water flow through your aquarium can cause low levels of electrical current flow through you tank if you have a voltage leak.
You also don't take 2 failed pieces of equipment into account. Worst case you have 2 failing electrical devices from opposite sides of the 220V circuit. This can cause current to flow within the tank between the 2 devices with or without a ground probe. Even if they are both from the same 120V source, if one is a heater (resistive) and one is a motor (inductive) you can still have a difference in potential between the 2 causing current to circulate in your tank.
I am a firm believer in protecting the fish as well as the people. There is a way to protect the fish by using DC pumps on a battery backup or non gfci circuit without getting away from the GFCI and ground probe for less critical equipment.

 

[Windy]

Grounding Probes Debunked


1

Robert C. Michelson

Electrical Engineering Professor, Georgia Institute of Technology

Conventional wisdom found in magazine articles and in the bowers of World Wide Web chat

rooms indicated that “voltage” in aquaria is one of the factors that can cause Hole in the Head

and Lateral Line Erosion. We read quotes like, “Stray voltage is something that exists in every

tank. Stray voltage can be eliminated with a simple ground probe available at most pet shops in

the twenty dollar range. Elimination of stray voltage is a simple step in reducing the stress on

your fish. Every marine tank should be grounded for your protection and that of your fish.”

Is it true? Well not exactly, and as I will discuss below, the addition of a ground probe may even

make matters worse!

Clearly electrical items submerged within your aquarium (power heads, heaters, etc.) can provide

a direct interface between the prime power source (120 volts alternating (60 Hz) current (VAC)

in the United States and 220 VAC, 50 Hz in most of the rest of the world) and the water, but

some claim that the stray voltages can be indirectly induced by the lighting systems. This is

possible because the skin depth of salt water (a conductor) at 60 Hz is not zero. “Skin depth” is

the distance that electromagnetic energy can penetrate a conductor. Salt water is a conductor, but

not a perfect conductor, so there is penetration by 60 Hz emissions. These induced voltages are

small in magnitude. On the other hand, shorted pumps can develop large currents through the

water, but typically between the “short” and some “ground” like your ground probe. This means

that the inclusion of a ground probe could make things worse. If a pump were shorting within

itself, the currents flowing through the water would remain local to the pump and should not be a

problem. You would have to have two shorting pumps, or a pump and a ground probe, or some

other current path to get electrical current to flow through your tank.

Direct shorts would have other ramifications. Copper or iron could be introduced into the

aquarium water as plating occurred. Other compounds would plate out as well since salt water

contains many ions in suspension. Electrolysis would occur, heating the water while it liberated

oxygen and hydrogen. There is of course a shock hazard.

Most people do not understand the problem however. Lots of web space has been devoted to the

measurement of voltage in aquariums... most of which is of no value. Voltage is not the problem,

current is. Voltages can exist without there being any current. For example, birds sitting on a


power line may be in direct contact with 10,000 volts, but they are not electrocuted. Why?

Because no current is flowing through their bodies. Voltage is the “potential” or force that drives

electrons through a conductor. The actual flow of electrons is the “current”. It is current that

kills. Were one of the birds sitting on the power line to simultaneously touch one of the other

wires on the transmission pole, a current path would be created (through the bird) and it would

be electrocuted (and probably incinerated as well). So what are you doing when you add a

grounding probe to your aquarium? You are providing a current path that might not already exist.

Any fish between the source and the grounding probe will experience a current flowing through

their bodies... not good!

Grounding Probes Debunked

2

Taking a volt meter and measuring a voltage in your aquarium relative to some arbitrary ground

point does not indicate that there is a current flowing through the salt water (conductive medium)

in your aquarium! It just means that the aquarium water is at a different potential than the ground

reference point that you chose.

Measuring a voltage between submerged points in your aquarium may be misleading if not done

correctly. The use of metallic probes can create a “battery effect” if dissimilar metals are

involved (think your volt meter probes are the same metal? What if they are chrome plated (most

are) and what if you’ve worn the chrome off one to expose brass or copper beneath?).

Also, some currents in salt water are perfectly natural as described below.

You can measure electrical currents everywhere-- the fact that salt water ions flow, actually

generates an electrical current. It’s unavoidable. The open ocean has lots of electrical currents

flowing. Some of these are caused by currents flowing through the Earth while others are

actually perturbations to local fields caused by the motion of objects (fish, turtles, etc.) in the

water. When I was tracking the Florida Manatee (Trichechus manatus) in the Banana and Indian


Rivers around the Kennedy Space center, we actually considered sensing the extremely low

frequency (ELF) emissions generated by the manatee’s tails as they accelerated the brackish or

salt water ions in the presence of the Earth magnetic field during vigorous swimming (alas,

manatees are not very energetic most of the time and other means were chosen (Sirenian

Tracking Project)). For example, the ampullae of Lorenzini in a shark’s nose detect minute


current flow disturbances in the water as an aid in locating prey.

I don't use any power heads and all of my pumps are totally external and physically isolated

(motor and pump head are separate). With the exception of an emergency heater in the sump, no

electrical appliances come in contact with the water.

There are all sorts of anecdotes about how much better the fish in a given tank will act and look

after adding one of these “grounding probes”. My belief is that if there are any stray currents in

the tank coming from an electrical appliance, the solution is not to try to draw the current away

with a grounding probe (symptom), rather, the appliance must be damaged and should be

replaced (cure).

Fish don’t like electrical current to flow through their bodies. When higher electrical current

levels flow through the water, fish will orient their bodies to minimize the potential (voltage)

across their bodies, thereby minimizing the electrical current flowing through their bodies. At

very low levels, the fish may only act strangely or seek areas of the aquarium where electrical

current is not flowing. It is doubtful that continuous current flow through a fish’s body is

beneficial, and may in fact be the source of anecdotal reports of Hole in the Head disease and

Lateral Line Erosion. If your tank is at a different potential from the “ground” in your house, no

electrical current may exist in your tank based on this static voltage. However as soon as you

ground your tank by inserting a “grounding probe”, you will be guaranteed to have electrical

current flowing even if the voltage drops.

Grounding Probes Debunked

3

For a technical discussion of stray voltage in aquaria and the use of Ground Fault Interrupters,

click here. (http://angel-strike.com/aquarium/GFI&TechnicalDetails.html)

In conclusion, the addition of a “grounding probe” will guarantee an electrical current flow in

your aquarium and may induce erratic behavior or disease in your fish. If you have defective

aquarium appliances that are creating a current path in your aquarium by using the salt water as a

conductive medium, then the solution is to repair the appliances or replace them... not divert a

portion of the current into a “grounding probe”.

 

[Brew12]

Grounding Probes Debunked

Umm... ok. Where to begin.
Skin effect (or as he calls it skin depth) - This has absolutely nothing to do with inducing voltages from one conductor to another. This phenomena is why most substations use pipe shaped conductors and old power lines are hollow. Very little current flows in the middle and concentrates on the outside. No impact on aquariums at all.
Leaching lead and iron - maybe back in the late 1990's when he wrote this article but not true today. Most ground probes today are made from titanium. Do you really think titanium will leach lead and iron through plating?
He only uses inline pumps and no powerheads or other electrical devices in his tank. The only electrical device he has in it is an emergency heater. How many aquarists do you think follow that advice? So sure, if you are set up that way go for it. If you have 2 power heads in your tank and do not have a ground probe that is exactly like having 1 powerhead and a ground probe. Again, his concept only works if you have no electrical equipment in your tank.
If you put your electrical equipment in a sump, along with your ground probe, it removes almost every other concern he had.

There, I hope that debunks the fact that ground probes are debunked. Just like any other piece of safety equipment there is a proper way to use them and an improper way. Used correctly they are an excellent way to protect yourself, your home, and your family.

 

[Paul B]

I agree.

 

[Turbo's Aquatics]

some claim that the stray voltages can be indirectly induced by the lighting systems

So what are you doing when you add a grounding probe to your aquarium? You are providing a current path that might not already exist.

but typically between the “short” and some “ground” like your ground probe. This means that the inclusion of a ground probe could make things worse

this is actually covered better in the article linked (and quoted below)

If a pump were shorting within itself, the currents flowing through the water would remain local to the pump and should not be a problem

...until someone who is grounded sticks their hand in the tank...

Voltage is not the problem, current is

This is true

For example, birds sitting on a power line may be in direct contact with 10,000 volts, but they are not electrocuted

True but actually a bird typically can't sit on a very high voltage power line because of electrostatic repulsion. I can't recall how high the voltage has to be but this was one of those trick problems that our EE prof hit us with once. The situation was that someone wanted to "protect the birds" by adding a shield to the conductor...one of those mind games engineering professors like to play to get us all to think. Just wanted to share that story, I don't get to tell that one often lol

My belief is that if there are any stray currents in the tank coming from an electrical appliance, the solution is not to try to draw the current away with a grounding probe (symptom), rather, the appliance must be damaged and should be replaced (cure).

Yes, but our point here though, again, is to protect the human from getting killed

Fish don’t like electrical current to flow through their bodies

What about electric eels?

Personally I found the link at the bottom more interesting

http://angel-strike.com/aquarium/GFI&TechnicalDetails.html

Many folks drop a grounding probe in their tanks and connect it to a water pipe or the neutral in their wiring thereby creating a current path where one might otherwise NOT have existed. This is worse for the fish than a very localized current (short within a pump housing) or a static voltage. The Safety to the aquarist is a different issue. What about the use of Ground Fault Interrupters (GFI) to protect the aquarist?

Fuses and circuit breakers are too slow to protect one from shock . They protect equipment, not people. The GFI is electronic and faster (GFI = 10 ms). A grounding probe has to be used as a GFI reference before it will work properly. I use GFIs all over my system. It must be understood however that using GFIs on pumps and lights isn't necessarily going to stop detrimental currents in the aquarium.

For example, if one power head's hot lead (black wire) is exposed to the water and another power head's neutral lead (white wire) is exposed to the water, then there will be a current flow between them as well as any sea life that gets in the way. Lets say that both power heads were plugged into the same GFI. Since all the current coming in the black wire is going out the white wire (some through the power heads, some through the water and fish)... there is a balance, but an unhealthy one for the tank. The GFI would not trip. Adding a ground probe would cause the GFI to trip in this example.

Second example: If a GFI is used on the pumps and lights and there is a grounding probe in place, any "induced" voltage will cause a current through the water and out the ground probe. Light, heat, motion, and induced electrical currents all represent "consumed energy". The current into the "emitter" of these energies will be the same as the current going out of the emitter. The circuit is balanced and the GFI will not trip, but energy is still created in various forms which can be transmitted to the aquarium. Consider an improbable case that will illustrate this point.

Suppose I had a motor (like we'd find in a power head) and I supply it power from a GFI-protected source. Then I properly install a ground probe. Now lets say that I connected an electrical generator to the motor through an insulated mechanical coupling. When the motor is turned on, it turns the generator which in turn creates a voltage. I will then connect one side of the generator to ground and the other side to my aquarium water. What will happen? Current will flow through the aquarium and out the ground probe. Will the GFI detect this and trip? No, because even through its current results from the motor-driven generator's energy, the motor's lines remain balanced.

So now we have a system that can electrocute both the aquarist and the fish even though there is a properly installed GFI and ground probe. Were I to remove the ground probe, there would no longer be a current path affecting the fish (they are now the "birds on a wire"). The aquarist however, is still at risk if he touches the water and a ground.

In reality, induced voltages and currents will be small... so small that they are probably NOT an issue for the safety of the aquarist, but with a grounding probe present, they could be unhealthy for the fish and coral (and I suspect they probably are, since sea life has little insulation to mitigate the current flow through their bodies. I can't believe that a continuous current flowing through one's body would not cause havoc with cellular ion transport, not to mention the "jamming" of sensory organs).

While I can't see the example that is being given really applying, it does illustrate well.

This is interesting...thanks for sharing it @Windy I was at first thinking of negating a bunch of stuff in that article but he does make a point.

Basically, we've got two solutions: one that for sure protects us humans, and one that appear to eliminate stray currents which are theorized to cause harm to inhabitants (and they likely don't help)

So the question becomes this: How does one do both? Did I misunderstand something? I'm too busy to get into the math and engineering about it all today...but I would say, don't discount this line of thinking quite so fast y'all...I think it's worth discussing

 

[Brew12]

True but actually a bird typically can't sit on a very high voltage power line because of electrostatic repulsion. I can't recall how high the voltage has to be but this was one of those trick problems that our EE prof hit us with once.

Just an FYI, it has nothing to do with magnetism (electrostatic repulsion). It has to do with corona, which is the ionizing of the air around the high voltage source. This phenomena sounds like buzzing hornets when it gets bad and feels like you are being poked by thousands of needles. This is why high voltage linemen wear corona suits when they do live line work on high voltage systems.

As for what voltage? It really depends on the weather. Anything 161,000 volts or less won't cause problems. We never see birds on our 500kV lines. I don't have as much experience with 345kV systems but I image that is around where the cutoff would be.

 

[Brew12]

Basically, we've got two solutions: one that for sure protects us humans, and one that appear to eliminate stray currents which are theorized to cause harm to inhabitants (and they likely don't help)

I wanted to reply to this post separately and it goes along with a previous post. The only way to eliminate all stray current from a tank is to put nothing electrical in it. This is the option the author of the article has chosen. The only electrical device he has in his tank is a heater and that only turns on for emergency use.
If you have 1 electrical component in your system you run the risk of stray currents. It does not matter if you use a ground probe or not. That electrical component could produce stray currents to algae or salt buildup on your tank that connects to ground such as on electrical cords or PVC pipe. If you have 2 electrical components you can have stray current between the two.
Aside from the articles technical flaws, the entire concept just doesn't apply in most aquarium applications and doesn't take a non perfect world into account (other than electrical equipment failing).

 

[Turbo's Aquatics]

Just an FYI, it has nothing to do with magnetism (electrostatic repulsion). It has to do with corona, which is the ionizing of the air around the high voltage source. This phenomena sounds like buzzing hornets when it gets bad and feels like you are being poked by thousands of needles. This is why high voltage linemen wear corona suits when they do live line work on high voltage systems.

As for what voltage? It really depends on the weather. Anything 161,000 volts or less won't cause problems. We never see birds on our 500kV lines. I don't have as much experience with 345kV systems but I image that is around where the cutoff would be.

Thanks for the refresher! I could have sworn that it had something to do with the birds' feathers and that was the reason you don't see them on the lines. I could have been the explanation too and the prof was just wrong (he "assumed" that was what it was)

 

[Turbo's Aquatics]

Aside from the articles technical flaws, the entire concept just doesn't apply in most aquarium applications and doesn't take a non perfect world into account (other than electrical equipment failing).

My problem is that it still doesn't help me to understand exactly.

The problem is that while I may have had enough smarts to graduate as an EE and ~15 years later pass the PE/power exam on the first try, I can't say that it's something that I am super passionate about. So yeah I can work numbers and understand math really well but when it comes to conceptual issue and situations, I am almost completely a visual learner. So can read articles about it left and right and I'll get it eventually but if I want to learn and understand it quickly, I need a picture or I need to get my hands on something and tinker. Then for most people who are wholly unfamiliar with the concepts we are discussing here, my guess is that the same picture would be about the only way to explain it.

 

[Brew12]

I'm not a degreed engineer but I received my training in the navy. That said, I now have several engineers who work for me. My official job title is "Electrical Engineer - Power Systems". I taught electrical theory at a nuclear laboratory for several years before moving to heavy industry. I also wrote our sites electrical safety policies. Needless to say, power distribution and electrical safety are both passions of mine.

I could have sworn that it had something to do with the birds' feathers

It does. All the air gaps in the feathers make birds very sensitive to corona since the air gaps create pin arcing. Humans don't suffer from corona effects until a higher voltage because of our smooth skin.

My problem is that it still doesn't help me to understand exactly.

I love teaching and will help explain anything I can. For instance, lets say you have a metal rimmed tank. If you have algae growth on the back of the tank that goes up to the rim, you have a path for your electrical gear to track to your tank. If you have it on a metal stand everything connected to your stand is a ground source. If you have salt tracking on the back, that can be a path to ground. A ground probe is far from the only possible path for current flow in an aquarium. It is just the one we have the most control over.

 

[Windy]

Grounding Probes Debunked


1

Robert C. Michelson

Electrical Engineering Professor, Georgia Institute of Technology

Conventional wisdom found in magazine articles and in the bowers of World Wide Web chat

rooms indicated that “voltage” in aquaria is one of the factors that can cause Hole in the Head

and Lateral Line Erosion. We read quotes like, “Stray voltage is something that exists in every

tank. Stray voltage can be eliminated with a simple ground probe available at most pet shops in

the twenty dollar range. Elimination of stray voltage is a simple step in reducing the stress on

your fish. Every marine tank should be grounded for your protection and that of your fish.”

Is it true? Well not exactly, and as I will discuss below, the addition of a ground probe may even

make matters worse!

Clearly electrical items submerged within your aquarium (power heads, heaters, etc.) can provide

a direct interface between the prime power source (120 volts alternating (60 Hz) current (VAC)

in the United States and 220 VAC, 50 Hz in most of the rest of the world) and the water, but

some claim that the stray voltages can be indirectly induced by the lighting systems. This is

possible because the skin depth of salt water (a conductor) at 60 Hz is not zero. “Skin depth” is

the distance that electromagnetic energy can penetrate a conductor. Salt water is a conductor, but

not a perfect conductor, so there is penetration by 60 Hz emissions. These induced voltages are

small in magnitude. On the other hand, shorted pumps can develop large currents through the

water, but typically between the “short” and some “ground” like your ground probe. This means

that the inclusion of a ground probe could make things worse. If a pump were shorting within

itself, the currents flowing through the water would remain local to the pump and should not be a

problem. You would have to have two shorting pumps, or a pump and a ground probe, or some

other current path to get electrical current to flow through your tank.

Direct shorts would have other ramifications. Copper or iron could be introduced into the

aquarium water as plating occurred. Other compounds would plate out as well since salt water

contains many ions in suspension. Electrolysis would occur, heating the water while it liberated

oxygen and hydrogen. There is of course a shock hazard.

Most people do not understand the problem however. Lots of web space has been devoted to the

measurement of voltage in aquariums... most of which is of no value. Voltage is not the problem,

current is. Voltages can exist without there being any current. For example, birds sitting on a


power line may be in direct contact with 10,000 volts, but they are not electrocuted. Why?

Because no current is flowing through their bodies. Voltage is the “potential” or force that drives

electrons through a conductor. The actual flow of electrons is the “current”. It is current that

kills. Were one of the birds sitting on the power line to simultaneously touch one of the other

wires on the transmission pole, a current path would be created (through the bird) and it would

be electrocuted (and probably incinerated as well). So what are you doing when you add a

grounding probe to your aquarium? You are providing a current path that might not already exist.

Any fish between the source and the grounding probe will experience a current flowing through

their bodies... not good!

Grounding Probes Debunked

2

Taking a volt meter and measuring a voltage in your aquarium relative to some arbitrary ground

point does not indicate that there is a current flowing through the salt water (conductive medium)

in your aquarium! It just means that the aquarium water is at a different potential than the ground

reference point that you chose.

Measuring a voltage between submerged points in your aquarium may be misleading if not done

correctly. The use of metallic probes can create a “battery effect” if dissimilar metals are

involved (think your volt meter probes are the same metal? What if they are chrome plated (most

are) and what if you’ve worn the chrome off one to expose brass or copper beneath?).

Also, some currents in salt water are perfectly natural as described below.

You can measure electrical currents everywhere-- the fact that salt water ions flow, actually

generates an electrical current. It’s unavoidable. The open ocean has lots of electrical currents

flowing. Some of these are caused by currents flowing through the Earth while others are

actually perturbations to local fields caused by the motion of objects (fish, turtles, etc.) in the

water. When I was tracking the Florida Manatee (Trichechus manatus) in the Banana and Indian


Rivers around the Kennedy Space center, we actually considered sensing the extremely low

frequency (ELF) emissions generated by the manatee’s tails as they accelerated the brackish or

salt water ions in the presence of the Earth magnetic field during vigorous swimming (alas,

manatees are not very energetic most of the time and other means were chosen (Sirenian

Tracking Project)). For example, the ampullae of Lorenzini in a shark’s nose detect minute


current flow disturbances in the water as an aid in locating prey.

I don't use any power heads and all of my pumps are totally external and physically isolated

(motor and pump head are separate). With the exception of an emergency heater in the sump, no

electrical appliances come in contact with the water.

There are all sorts of anecdotes about how much better the fish in a given tank will act and look

after adding one of these “grounding probes”. My belief is that if there are any stray currents in

the tank coming from an electrical appliance, the solution is not to try to draw the current away

with a grounding probe (symptom), rather, the appliance must be damaged and should be

replaced (cure).

Fish don’t like electrical current to flow through their bodies. When higher electrical current

levels flow through the water, fish will orient their bodies to minimize the potential (voltage)

across their bodies, thereby minimizing the electrical current flowing through their bodies. At

very low levels, the fish may only act strangely or seek areas of the aquarium where electrical

current is not flowing. It is doubtful that continuous current flow through a fish’s body is

beneficial, and may in fact be the source of anecdotal reports of Hole in the Head disease and

Lateral Line Erosion. If your tank is at a different potential from the “ground” in your house, no

electrical current may exist in your tank based on this static voltage. However as soon as you

ground your tank by inserting a “grounding probe”, you will be guaranteed to have electrical

current flowing even if the voltage drops.

Grounding Probes Debunked

3

For a technical discussion of stray voltage in aquaria and the use of Ground Fault Interrupters,

click here. (http://angel-strike.com/aquarium/GFI&TechnicalDetails.html)

In conclusion, the addition of a “grounding probe” will guarantee an electrical current flow in

your aquarium and may induce erratic behavior or disease in your fish. If you have defective

aquarium appliances that are creating a current path in your aquarium by using the salt water as a

conductive medium, then the solution is to repair the appliances or replace them... not divert a

portion of the current into a “grounding probe”.

 

[Turbo's Aquatics]

Why did you post that again in the same thread? I'm totally confused...

 

[Beej1254]

Why did you post that again in the same thread? I'm totally confused...

Me too.

 

[Joey waid]

Me too.

Me three. Beating a dead fish..