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I'm sorry
I don't know how to say it any differently
stray voltage and gfci (safety)
- Thread starter grouper therapy
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I'm sorry
I don't know how to say it any differently
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- Reaction score
- 7
If you have no stray voltage a grounding probe should be used along with a gfci for your protection. It should not be used in the attempt to ground faulty equipment that is producing stray voltage.
I have been following this thread, and have some interest in this topic as well. Some of my thoughts-
1) GFCI's (Ground Fault Circuit Interuptor's) are required on all electrical circuits around wet locations per the National Electric Code, and for good reason. If you don't have these devices on ALL circuits connected to your aquariums, you may want to reconsider. While not difficult to install, if you are not comfortable working with electricity, technically articulate and somewhat handy; you may want to hire a licensed electrician (or others at your own risk) to install them.
2) The electrical resistance of human skin varies from about 1,000ohms when wet to about 100,000ohms dry. I always use the range of 3,000(perspiring), to 30,000 as the 'expected' range, under normal circumstance.
3) When we immerse our bodies (hands for example) in seawater, you can bet that we are "in intimate electrical contact" with the water (as my physics professor used to say). The 1,000ohms might even be too high, which would be worse for us as you will see. The current that might flow through our body may be calculated by Ohm's law.
I = E/R ; where I=amperes (current), E=volts and R=ohms (resistance)
so
I = 115 volts / 1000 ohms
I= 0.115 amperes or 115 milliamps
Now the average person may be electrocuted by as little as 50 or 60 milliamps! Lower body resistance will make this number be higher.
Houston, I think we may have a problem!
4) A special hazard exists when the electrical current flows through your heart. This typically happens, when touching 'differences of electrical potential' with your two hands. For example, grabbing a bare energized wire with one hand, and simply touching either the other conductor, or ANY grounded conducting object with your other hand. The current flows into one hand, through the chest and out the other hand. Many of us have had this happen, and lived to tell about it. Why? Most likely because our body resistance was above the 3,000ohms mentioned above. At 3,000ohms 115 volts AC would yield 38 milliamps of current. Enough to get our attention, but not likely enough to kill us (see how close you came to dying!). When we have our hands covered in seawater we are at special risk, due to the high conductivity of the salt ions.
5) In addition, 60 hertz is the frequency at which alternating current (in the US and Canada), also known as 'AC', changes direction. It does this 60 times per second. That also happens to be almost the worst possible frquency to expose the heart to, in that it can cause the heart to lose it's rhythm, also known as going into a state of fibrillation. This is where the heart attempts to beat in high speed uncoordinated movement, or 'flutter'. The heart loses the ability to beat in a slower coordinated and efficient rhythm. If this condition lasts more than a few minutes without medical intervention or CPR, our organs begin to suffer from lack of oxygen and we begin to die.
I don't carry enough professional liability coverage to to make any broad statement about grounding probes, other than I have maintained aquaria both with and without them. I concur with previous statements for them theoretically making things safer for humans, IF used WITH a GFCI. I do not suggest connecting to outlet cover screws, but instead make the connection to a known ground buss connection (intimate electrical contact, or don't use it).
As for our fishes, evaluate grounding probes as you see fit. I have discovered several things about ground probes, that I think worthy of consideration.
A) Every commercial probe that I have seen was made from Titanium. There may be others made of different materials/metals, but I have not seen any.
B) Grounding probes will begin to foul over time, and accummulate a layer of 'biofilm/deposits'. If used, I would wipe them down periodically. Otherwise they become less 'intimately electrically contacted' with the water, and build up electrical resistance/become less conductive. This is counter to their purpose.
C) In spite of all assertions and most common understanding, titanium metal IS NOT INERT. It forms titanium dioxide film quite readily at room conditions. Titanium dioxide is an electrical semiconductor, and significantly less conductive than titanium metal. Personally, I have found metal alloys that I feel are both much more inert chemically and at the same time better conductors. Caveat emptor.
Regarding stray voltages from electrical aparatus, that is a very complex and highly theoretical topic. It involves analyzing the 'complex circuits' that are our aquaria, and inductive and capacitive coupling and reactance. I think it is beyond the scope of this thread.
The parts above on isolating faulty apparatus were great! One of the most important lessons I ever learned was 'to never overlook the obvious'.
I have worked with electricity all of my life and lived to tell about it. I would like to think it was by not being foolish, and working safely. This includes working on circuits employing greater than 60,000 volts. While I have had the crap knocked out of me a few times, it always happened when I wasn't paying attention like I should. Be careful. Electricity is mostly invisible, and poorly understood by many. Learn to respect it, then learn at least a little about how it behaves. You will be better off for it.
The above statements are opinions. Any use is at your own risk.
(sorry, my lawyers made me do it
1) GFCI's (Ground Fault Circuit Interuptor's) are required on all electrical circuits around wet locations per the National Electric Code, and for good reason. If you don't have these devices on ALL circuits connected to your aquariums, you may want to reconsider. While not difficult to install, if you are not comfortable working with electricity, technically articulate and somewhat handy; you may want to hire a licensed electrician (or others at your own risk) to install them.
2) The electrical resistance of human skin varies from about 1,000ohms when wet to about 100,000ohms dry. I always use the range of 3,000(perspiring), to 30,000 as the 'expected' range, under normal circumstance.
3) When we immerse our bodies (hands for example) in seawater, you can bet that we are "in intimate electrical contact" with the water (as my physics professor used to say). The 1,000ohms might even be too high, which would be worse for us as you will see. The current that might flow through our body may be calculated by Ohm's law.
I = E/R ; where I=amperes (current), E=volts and R=ohms (resistance)
so
I = 115 volts / 1000 ohms
I= 0.115 amperes or 115 milliamps
Now the average person may be electrocuted by as little as 50 or 60 milliamps! Lower body resistance will make this number be higher.
Houston, I think we may have a problem!
4) A special hazard exists when the electrical current flows through your heart. This typically happens, when touching 'differences of electrical potential' with your two hands. For example, grabbing a bare energized wire with one hand, and simply touching either the other conductor, or ANY grounded conducting object with your other hand. The current flows into one hand, through the chest and out the other hand. Many of us have had this happen, and lived to tell about it. Why? Most likely because our body resistance was above the 3,000ohms mentioned above. At 3,000ohms 115 volts AC would yield 38 milliamps of current. Enough to get our attention, but not likely enough to kill us (see how close you came to dying!). When we have our hands covered in seawater we are at special risk, due to the high conductivity of the salt ions.
5) In addition, 60 hertz is the frequency at which alternating current (in the US and Canada), also known as 'AC', changes direction. It does this 60 times per second. That also happens to be almost the worst possible frquency to expose the heart to, in that it can cause the heart to lose it's rhythm, also known as going into a state of fibrillation. This is where the heart attempts to beat in high speed uncoordinated movement, or 'flutter'. The heart loses the ability to beat in a slower coordinated and efficient rhythm. If this condition lasts more than a few minutes without medical intervention or CPR, our organs begin to suffer from lack of oxygen and we begin to die.
I don't carry enough professional liability coverage to to make any broad statement about grounding probes, other than I have maintained aquaria both with and without them. I concur with previous statements for them theoretically making things safer for humans, IF used WITH a GFCI. I do not suggest connecting to outlet cover screws, but instead make the connection to a known ground buss connection (intimate electrical contact, or don't use it).
As for our fishes, evaluate grounding probes as you see fit. I have discovered several things about ground probes, that I think worthy of consideration.
A) Every commercial probe that I have seen was made from Titanium. There may be others made of different materials/metals, but I have not seen any.
B) Grounding probes will begin to foul over time, and accummulate a layer of 'biofilm/deposits'. If used, I would wipe them down periodically. Otherwise they become less 'intimately electrically contacted' with the water, and build up electrical resistance/become less conductive. This is counter to their purpose.
C) In spite of all assertions and most common understanding, titanium metal IS NOT INERT. It forms titanium dioxide film quite readily at room conditions. Titanium dioxide is an electrical semiconductor, and significantly less conductive than titanium metal. Personally, I have found metal alloys that I feel are both much more inert chemically and at the same time better conductors. Caveat emptor.
Regarding stray voltages from electrical aparatus, that is a very complex and highly theoretical topic. It involves analyzing the 'complex circuits' that are our aquaria, and inductive and capacitive coupling and reactance. I think it is beyond the scope of this thread.
The parts above on isolating faulty apparatus were great! One of the most important lessons I ever learned was 'to never overlook the obvious'.
I have worked with electricity all of my life and lived to tell about it. I would like to think it was by not being foolish, and working safely. This includes working on circuits employing greater than 60,000 volts. While I have had the crap knocked out of me a few times, it always happened when I wasn't paying attention like I should. Be careful. Electricity is mostly invisible, and poorly understood by many. Learn to respect it, then learn at least a little about how it behaves. You will be better off for it.
The above statements are opinions. Any use is at your own risk.
(sorry, my lawyers made me do it
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This is a good read. I do use grounding probes on all my tanks. The current will find or follow the path of least resistance. My theory is to eliminate any problems but unless you, as said in this discusion, make the path, not only touch the water but also a rock, side of the tank, ground, etc. you will most likely not feel a thing even if there is stray voltage. Once you test with a voltmeter and find NO stray voltage you can set your multi-meter on current (milli-amps) and dheck if there is any stray current. One probe to a ground and the other to pieces of equipment and in the water. Most home meters will show pretty low voltages but unless you have a pretty good meter it will not show up very low voltages. I said this in a post a few weeks ago, I'm one of those that put one hand on a good ground and the other in the water. I do not recommend this method to anybody.
Another place that you can induce voltages into the water is with what is called EMF (electro magnetic force). All electrical wires going into a tank that have electricity going thru them have a magnetic field around them. If they do not have good insultion or just poorly designed they could induce voltages. I had an older pump (small 90 gph) that was used in a seahorse tank. Even though the cord looked good the pump itself could have been leaking. Felt the voltage/current measured it to be 60+ vac. After removing the pump voltage dropped to a couple of volts @ 15ma. Ground probe took that down to zero. I do not buy the $20 ground probes. even though I do have one, I use stainless steel wire. Works great ! I do recommend that you test your GFIs regularly. Most of them have a test button. They should trip immediately or quicker. LOL Oh and by the way those that are interested some of them use what is called a Metal Oxcide Varistor (MOV). This is a semi-conductor that will short immediated 10-20 milli-seconds or quicker, I forget the exact number. Another thing that is great to have on electricals is a surge protector like you should use on your computers. If lightning or voltage surges this very cheep equipment can save you a bunch of money on blown out controllers, pumps, etc, Its much cheeper to replace a $6 poer strip with surge protection than a 300-500 controller.
Just some added food for thought.
Another place that you can induce voltages into the water is with what is called EMF (electro magnetic force). All electrical wires going into a tank that have electricity going thru them have a magnetic field around them. If they do not have good insultion or just poorly designed they could induce voltages. I had an older pump (small 90 gph) that was used in a seahorse tank. Even though the cord looked good the pump itself could have been leaking. Felt the voltage/current measured it to be 60+ vac. After removing the pump voltage dropped to a couple of volts @ 15ma. Ground probe took that down to zero. I do not buy the $20 ground probes. even though I do have one, I use stainless steel wire. Works great ! I do recommend that you test your GFIs regularly. Most of them have a test button. They should trip immediately or quicker. LOL Oh and by the way those that are interested some of them use what is called a Metal Oxcide Varistor (MOV). This is a semi-conductor that will short immediated 10-20 milli-seconds or quicker, I forget the exact number. Another thing that is great to have on electricals is a surge protector like you should use on your computers. If lightning or voltage surges this very cheep equipment can save you a bunch of money on blown out controllers, pumps, etc, Its much cheeper to replace a $6 poer strip with surge protection than a 300-500 controller.
Just some added food for thought.
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