An electricty safety comment I havent seen elsewhere

jared555

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Sorry if I missed the obvious post somewhere. But I have seen a few posts where people didn't seem to understand this.

Your fish have a very unlikely chance of being injured by electrocution in the tank. So if you accidentally damage something electrical in your tank (post I was reading was about glass heaters) do not look and see your fish are fine and assume it is safe to touch the water.

If everything else in the tank is set up correctly the only time electricity can flow to ground is if you touch the water which means in all likelihood anywhere from 120-240 (or more in the case of some lighting) is going to flow through your body).

If you make the unfortunate mistake of touching something that is grounded with your other hand while touching the electrified water there is going to be a lot of current traveling across your heart.

If you get shocked once when you touch the water the best solution to checking if you have fixed the problem would be to take a voltmeter (it doesn't have to be an expensive one) with clean probes, touch one to the water and the other to something grounded. If you know for sure which prong in an outlet is ground use that.

If you are making your own DIY equipment you should familiarize yourself with usage of a multimeter. When you are done building your project you should check multiple surfaces (water, metal surfaces, etc.) to see if you have a shock hazard.

Someone else could make a guide on how to safely check things with a multimeter but I do not want to take the risk of giving misinformation resulting in injury.

Again, odds are even if the water is electrified and you shock yourself, your fish will be fine. The danger to you increases greatly if you are working with saltwater aquariums as the conductivity of the water is much greater.

The piece of faulty equipment does not have to be in the tank you are working with. If it is connected by metal or water in any way (sumps, refrugium, filters, etc.) you can still be shocked. This means people with centralized filtration could have to find exactly which tank's equipment is faulty.


Sorry for the long post but I hope it helps at least some individuals here.
 

DragonScales

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Thanks for the post. This is something a lot of people over looked and take it for granted that it cannot happen to them.
 

jared555

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cichlidfinder;3163472; said:
They make grounding probes for fish tanks. When using one if you had a heater tube break it would trip the breaker.

http://www.marinedepot.com/ps_AquariumPage~PageAlias~miscellaneous_titanium_grounding_probe.html
I had wondered if there was something like this or a probe you could stick into your tank that would light up if any stray voltage was present. This device would work best if you had a GFCI circuit, otherwise there is a CHANCE that it would not actually trip the breaker (if there is enough resistance between the source of the electricity and the probe).

It should theoretically stop you from being shocked (there is still a chance) as long as the wire to the probe can handle all of the current trying to flow through it and a few other factors.

My point in posting this was to hopefully get people thinking (and maybe suggest products like that) because I have seen numerous posts where people have been shocked and were talking like it was no big deal.

And for anyone doubting that there could be resistance in a water environment...
1) If you took water straight from a RO/DI unit, there is a fairly good chance it wouldn't conduct electricity significantly. (I only know for a fact that distilled water is this way).

It is impurities in the water that cause it to conduct electricity. As soon as you add impurities (and especially if you mix in salt) the water becomes more and more conductive. For reference: http://en.wikipedia.org/wiki/Water_(molecule)#Electrical_conductivity

I do not suggest that anyone test this unless you know how to do it safely.

2) A heating element (in most cases like this) is just a big resistor. If water is only in contact with the 'neutral' side of the heating element the current is limited to the wattage of the heating element. (The same applies to many other electronic devices)
 

Oddball

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Posted this a while back. Maybe it'll help:

Grounding Probe

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!

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. Its 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 ). 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.

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

In conclusion, the addition of a “grounding probes” 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”.


Technical Considerations Regarding Static Potentials

Someone once asked the question, "If an aquarium exhibits a static potential above ground, wouldn't a ground probe dissipate this static potential differential with essentially "zero" current flow, after the initial voltage was dissipated?" To answer this, we must have an understanding of what these static potentials are.

Voltage is a potential difference. The generator of the voltage doesn't go away unless the static voltage is truly static (as in a capacitor). If the "static voltage" is one created by induction, it will still be present to generate some kind of current even if shorted through a ground probe. You may measure essentially no voltage, but you could still have current. How this affects fish and coral is an open question. People stick a volt meter probe in the water and touch something that they think is "ground". If they read a voltage, then they may be measuring an induced voltage (from lights or other things), and providing a current path isn't the answer if none already exists. True static voltages are "dissipatable" such as those generated by walking across a carpet (though these are probably not much of an issue with marine aquaria since there is usually so much conductive surface film (salt) that resistance will eventually dissipate such a charge).

Now, most people consider water to be impervious to electromagnetic waves, especially when its salt water because salt water is a conductor and would "short out" the radio waves, right? Well it is true the sea water has a conductivity of 4 Siemens/meter (as opposed to distilled water with a conductivity of only 0.0002 S/m, which is still high compared to something like glass at 0.00000000000001 S/m). In the presence of low frequency energy like 60 Hz, sea water is not a low-loss dielectric because of the mobility of the chlorine and hydrogen ions. Therefore induced charges (electrons) are able to diffuse throughout the volume of the aquarium water. This prevents a potential difference to be created across the resistance of the water or from any stored charge as in a capacitor.

Normally one would expect fluorescent bulbs to produce the most induced voltage in the tank. This is because of their relatively large surface area (compared to something like a power head), and the fact that the entire bulb length has an ionized gas within it that is radiating at 60 Hz. Since the bulb is short relative to the wavelength of 60 Hz (5,000 km or 3,107 miles in air) and it is close to the aquarium (typically only a few feet at most from the water surface), we consider the bulbs to be in the "near field" (well within 3 to 5 wavelengths), so transmission is by induction. Since the Intrinsic Impedance of Free Space (air) is 377 ohms and the Intrinsic Impedance of sea water at 60 Hz is (1+j)(0.0077) ohms we see that there is a large impedance mismatch. Were the bulbs to be in the far field (> 15,000 km distant) most of the energy would be reflected at the air-water interface, but since we are in the extreme near field, induction will occur and we will observe impressed voltages in our aquarium.

The higher the frequency, the less energy penetrates into a conductor. The amount to which penetration occurs is called "skin depth". At very high frequencies, electricity actually flows on the surface of copper conductors and not in the interior of the wire. Skin depth is related to frequency and conductivity and is different for different materials. The skin depth of sea water for 60 Hz energy is about 32.5 meters. In other words, 60 Hz current induced from outside the aquarium will exist on the outside 32.5 meters of the tank. Except for the largest tanks, this means that induced current densities from 60 Hz sources will permeate the aquarium uniformly.

A reference on the web for empirical data on aquarium voltage and current is http://www.aquarium.net/1298/1298_3.shtml


Ground Fault Interrupters (GFI) and Aquarist Safety

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).

Robert Michelson
Principal Research Engineer, Emeritus - Georgia Tech Research Institute
Adjunct Associate Professor (Ret.) - Georgia Institute of Technology
President - Millennial Vision, LLC
 

Oddball

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I posted this back in '05. Maybe it can be of use:

ZZAAPPed Again!! (Shocked by Tank)

If you've been in this hobby for a while, chances are you've been shocked by something connected to your tank(s). Especially anyone who has any kind of salts in their tank water. Wet electrical equipment and/or equipment with salt buildup (salt-creep) give optimal chances of someone receiving a shock. A lot of people use surge protectors on their tanks. While these surge protectors will protect your equipment from surges in your service lines, they won't necessarily protect anyone from being shocked. To achieve personal protection from mild to fatal shocks, there is the GFCI. These protective devices used to be out-of-range price-wise for most hobbyists. Now, they're very affordable and can be easily found in most hardware and department stores.
Here's an excerpt from doityourself.com which explains the function and types of GFCI protective devices:

The GFCI

A "GFCI" is a ground fault circuit interrupter. A ground fault circuit interrupter is an inexpensive electrical device that, if installed in household branch circuits, could prevent over two-thirds of the approximately 300 electrocutions still occurring each year in and around the home. Installation of the device could also prevent thousands of burn and electric shock injuries each year.
The GFCI is designed to protect people from severe or fatal electric shocks Because a GFCI detects ground faults, it can also prevent some electrical fires and reduce the severity of others by interrupting the flow of electric current.

The Problem

Have you ever experienced an electric shock? If you did, the shock probably happened because your hand or some other part of your body contacted a source of electrical current and your body provided a path for the electrical current to go to the ground, so that you received a shock.
An unintentional electric path between a source of current and a grounded surface is referred to as a "ground-fault." Ground faults ground-fault. Ground faults occur when current is leaking somewhere, in effect, electricity is escaping to the ground. How it leaks is very important. If your body provides a path to the ground for this leakage, you could be injured, burned, severely shocked, or electrocuted.

Some examples of accidents that underscore this hazard include the following:

* Two children, ages five and six, were electrocuted in Texas when a plugged-in hair dryer fell into the tub in which they were bathing.
* A three-year-old Kansas girl was electrocuted when she touched a faulty countertop

These two electrocutions occurred because the electrical current escaping from the appliance traveled through the victim to ground (in these cases, the grounded plumbing fixtures). Had a GFCI been installed, these deaths would probably have been prevented because a GFCI would have sensed the current flowing to ground and would have switched off the power before the electrocution occurred.

How the GFCI Works

In the home's wiring system, the GFCI constantly monitors electricity flowing in a circuit, to sense any loss of current. If the current flowing through the circuit differs by a small amount from that returning, the GFCI quickly switches off power to that circuit. The GFCI interrupts power faster than a blink of an eye to prevent a lethal dose of electricity. You may receive a painful shock, but you should not be electrocuted or receive a serious shock injury.
Here's how it may work in your house.. Suppose a bare wire inside an appliance touches the metal case. The case is then charged with electricity. If you touch the appliance with one hand while the other hand is touching a grounded metal object, like a water faucet, you will receive a shock. If the appliance is plugged into an outlet protected by a GFCI, the power will be shut off before a fatal shock would occur.

Availability of GFCIs

Three common types of ground fault circuit interrupters are available for home use:

* Receptacle Type: This type of GFCI is used in place of the standard duplex receptacle found throughout the house It fits into the standard outlet box and protects you against "ground faults' whenever an electrical product is plugged into the outlet Most receptacle-type GFCls can be installed so that they also protect other electrical outlets further "down stream" in the branch circuit.
* Circuit Breaker Type: In homes equipped with circuit breakers rather than fuses, a circuit breaker GFCI may be installed in a panel box to give protection to selected circuits The circuit breaker GFCI serves a dual purpose - not only will it shut off electricity in the event of a "ground-fault," but it will also trip when a short circuit or an overload occurs Protection covers the wiring and each outlet, lighting fixture, heater, etc. served by the branch circuit protected by the GFCI in the panel box.
* Portable Type: Where permanent GFCls are not practical, portable GFCls may be used One type contains the GFCI circuitry in a plastic enclosure with plug blades in the back and receptacle slots in the f rant. It can be plugged into a receptacle, then, the electrical product is plugged into the GFCI. Another type of portable GFCI is an extension cord combined with a GFCI. It adds flexibility in using receptacles that are not protected by GFCls.
 

jared555

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Thanks, oddball, for (re)posting that. The main reason I was mentioning voltage detection (rather than current) is if there is a significant voltage difference between the water and ground, excluding some other factors, you may have a significant shock hazard if somehow you become the path between the water and ground.

Also, if someone checks their tank for current with a multimeter (rather than voltage), there is a chance of frying the multimeter (or even catching something on fire) because you suddenly have lots of current flowing through small test leads. That would also be a concern of mine with a ground probe. Is that wire capable of handling 20 amps of power if there is a short or is it going to melt?

I personally think any circuits near aquariums (especially those that you have your equipment plugged into) should be GFCI. In some areas this might actually be legally required, I don't know.
 

JohnM

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Just one more thing to think about everybody it only takes .25 amps to stop your heart. So be careful and go that extra mile when messing with electricity. If you have to mess with it TEST,TEST,TEST.
 

jared555

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JohnM;3164929; said:
Just one more thing to think about everybody it only takes .25 amps to stop your heart. So be careful and go that extra mile when messing with electricity. If you have to mess with it TEST,TEST,TEST.
Depending on age and other factors it can be even less. If you get shocked it may not stop your heart, but cause fibrillation. 50/60 hz is most likely to interfere with your heart (which is unfortunately what 99% of equipment uses unless it is battery operated)

10-20 ma (0.01-0.02 amps or 1-4 watts) can potentially stop you from letting go of an object, or interfere with breathing

60 ma (0.06 amps or 6 - 12 watts) can cause fibrillation if it crosses your heart

100 ma (0.1 amps or 10-20 watts) from one hand to another can cause fibrilation

These numbers can be reduced depending on factors such as contact with water, age, etc.

You may be shocked by a 20 amp circuit at 110-240 volts and be fine, or it could stop your heart. When you have perfectly dry hands your chances of being shocked are reduced.

Remember, I am not trying to scare anyone out of this hobby, just trying to make people think and hopefully take extra precautions such as using GFCI for circuits around their tanks and making sure their DIY projects are safe.

Portable GFCI is not as effective, because if you spill water you may come directly in contact with the main circuit, but it is a very good start against preventing other shocks.
 

Iffrat

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spoken like the words of a true electrical engineer .. or someone who has done an amazing amount of research in electricity .. as a electrical biomedical engineer i try to explain how this stuff works but most of the time people just look at me and say .. " you stick a fork into a lite socket and it will kill you" and i just ~face+palm~

so thank you for being able to explain this in a way that most people can understand or beleve ..
 
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